Class : 1st year

No Absen : 934

The Earth always has day and night, and this happens because of its movement.

First, the Earth rotates on its axis. One full rotation takes about 24 hours.

Second, when one side of the Earth faces the Sun, that part has daylight. At the same time, the other side is dark and has night.

Third, as the Earth keeps rotating, places that were dark slowly turn to the Sun and get morning. Meanwhile, places that had light move away and get evening.

So, day and night happen because the Earth rotates on its axis, not because the Sun moves around us.

Class: XI AKL 1

Absent number: 26

Rain is one of the most important sources of fresh water on Earth. It is formed through a natural process that involves the movement of water in the atmosphere. This process is closely related to the water cycle.

First, the heat of the sun causes water from oceans, lakes, and rivers to evaporate into water vapor. This water vapor rises into the atmosphere.

Next, when the vapor reaches higher altitudes, the air becomes cooler. As a result, the water vapor condenses into tiny droplets that gather to form clouds.

After the clouds grow heavy and cannot hold the water any longer, the water falls back to the Earth’s surface as rain. In some cases, if the temperature is very low, it can fall as snow or hail instead.

The process of rain is essential for life because it provides water for humans, animals, and plants. Without rain, living things would not survive.

Class : XI AKL 1

No Absen : 34

Snow is frozen water vapor that falls from the atmosphere in the form of ice crystals. This natural phenomenon usually occurs in regions with very low temperatures, especially during winter.

The process of snow formation begins when water vapor in the air rises into cold layers of the atmosphere. The vapor cools down and turns into tiny ice crystals. These crystals then combine to form snowflakes. When the snowflakes become heavy enough, gravity pulls them down to Earth as snowfall.

Snow can only form when the temperature is at or below 0°C. That is why it is common in polar regions and high mountains. Each snowflake has a unique and symmetrical pattern, and it is said that no two snowflakes are exactly alike.

Snow is not only a sign of the winter season but also brings benefits. Snow stored in the mountains becomes a source of freshwater when it melts in spring. Moreover, snow influences the climate and serves as a popular attraction for tourism in many countries.

Link : britishcouncil.org, study.com,

Class : XI AKL 1

Absent Number : 16

A rainbow is a natural phenomenon that appears in the sky after rain. It looks like an arc of many colors, usually red, orange, yellow, green, blue, indigo, and violet. A rainbow happens because of the interaction between sunlight and raindrops in the atmosphere.

First, when sunlight passes through raindrops in the air, the light is refracted or bent.
Next, the light is reflected inside the raindrop.

Then, as the light exits the drop, it is bent again. This process is called dispersion, which separates the white sunlight into different colors. Each color bends at a different angle. Red bends the least so it appears on the outer edge, while violet bends the most and appears on the inner edge.

Finally, when millions of raindrops reflect and refract sunlight at the same time, we see a colorful arc in the sky called a rainbow. Sometimes, a double rainbow can appear when light reflects twice inside the raindrop, but it is fainter and has reversed colors.

In conclusion, a rainbow is formed by the refraction, reflection, and dispersion of sunlight in raindrops. That is why we usually see rainbows after rain when the sun shines.

• https://en.wikipedia.org/wiki/Rainbow

• https://education.nationalgeographic.org/resource/rainbow/

Class : XI AKL 1

No. Absen : 01

Flood is an overflow of water on land that exceeds the normal limit, inundating certain areas. This disaster often occurs in tropical regions with uneven topography, especially during heavy rainfall. In Indonesia, many areas are prone to floods.

Floods caused by garbage have become a serious problem in many cities. The pile of garbage in drainage channels blocks the water flow and triggers flooding in the surrounding areas. During the dry season, garbage accumulation in rivers or drains may not seem like a big issue. However, in the rainy season, it can become the beginning of a flood disaster.

When rainfall increases, the volume of water in rivers and drains also rises. The heavy rain makes the water discharge surge rapidly. But, due to garbage piles in narrow parts of the river or drainage, the water flow gets blocked. As a result, flooding occurs. Floating garbage worsens the situation by blocking the flow of water, polluting the environment, and threatening aquatic ecosystems.

The solution to this problem is proper waste management, including recycling, reducing single-use plastics, and regularly cleaning water channels.

https://tirto.id/proses-terjadinya-banjir-penyebab-dan-akibatnya-gWHl

Class : XI AKL 1

Number : 14

An earthquake is a natural event that occurs when the surface of the Earth shakes suddenly. It happens because of the movement of tectonic plates beneath the Earth’s crust. These plates are always moving slowly, but sometimes they get stuck due to friction.

When the pressure between the plates becomes too strong, the rocks break and release energy. This release of energy causes seismic waves that make the ground shake. The point inside the Earth where the rocks break is called the focus, and the point directly above it on the surface is called the epicenter. The closer an area is to the epicenter, the stronger the earthquake will be felt.

Sometimes, earthquakes can also trigger other natural disasters. For example, undersea earthquakes may cause a tsunami, while earthquakes in mountainous areas can cause landslides. That is why earthquakes are considered one of the most dangerous natural events.

In short, earthquakes happen because of the sudden release of energy from moving tectonic plates. Understanding this process helps people prepare for and reduce the impact of earthquakes.

Name: Ravanelli Putra M

Class: XI AKL 1

NO : 27

As we know now, global warming which is happening right now has a very big impact on natural conditions, animals and humans. Well, do you know how global warming which has a particularly serious impact on life happens? To know the process of how this phenomenon occurs, see the following explanation.

The process starts when sunlight shines the earth where most of the heat is absorbed by the earth and a half of it is reflected back onto the air (atmosphere). Sunshine returning to the air is trapped by gases in the atmosphere such as carbon dioxide, sulfur dioxide, methane, water vapor, and so on. This event is known as the greenhouse effect.

Solar radiation on the earth's atmosphere makes ozone layer get thinner and makes the sunlight which shines the Earth become hotter. The greenhouse effect also causes the sunlight which is reflected back onto space is reflected back into the earth. This phenomenon causes the earth continuously getting hotter. This condition is known as global warming.

https://en.m.wikipedia.org/wiki/Climate_change

Class: XI AKL 1

No. Absen: 09

Lightning is a sudden flash of light in the sky, usually during a thunderstorm. It happens because of electrical charges in the clouds.

First, when warm air rises and meets cold air, clouds form and water droplets move around quickly. This movement causes electrical charges to build up.

Second, the top of the cloud becomes positively charged, while the bottom becomes negatively charged. The difference in charges creates a very strong electric field.

Finally, when the electric field is strong enough, the charges are released suddenly as a bright flash of lightning. Sometimes, the lightning strikes the ground.

So, lightning happens because of the buildup and release of electrical charges in the atmosphere. 🌩️

https://share.google/Mn4FHqJ37CMXRIwGw

Kelas : XI AKL 1

No : 21

The seasons on Earth are not determined by the distance from the Sun but by the Earth’s axial tilt of 23.5°. Although Earth’s orbit is elliptical, with the closest point (perihelion) occurring in January and the farthest point (aphelion) in July, this distance difference does not significantly affect the climate. The main factor is the Earth’s tilt as it revolves around the Sun.

Around June 21, the Sun is directly overhead at the Tropic of Cancer, causing the Northern Hemisphere to tilt toward the Sun. As a result, sunlight strikes more directly, days are longer, and temperatures are warmer. Meanwhile, the Southern Hemisphere experiences winter. On March 21 and September 21, the Sun is directly above the equator, so day and night are nearly equal, about 12 hours each. On December 21, the Sun is overhead at the Tropic of Capricorn. The Southern Hemisphere receives more direct sunlight and enters summer, while the Northern Hemisphere tilts away from the Sun, leading to shorter days and colder temperatures.

The length of daylight also varies by location. At the equator, daylight is almost always about 12 hours. In the tropics, the change is small. In mid-latitudes, the difference is more noticeable, ranging from 9 to 15 hours. At the Arctic Circle, the Sun can remain above the horizon for 24 hours in summer but only for about 2 hours in winter. At the North Pole, there are six months of continuous daylight followed by six months of total darkness.

This axial tilt of the Earth is what causes the changing seasons as well as variations in the length of day and night. The farther from the equator, the greater the difference experienced.

https://www-weather-gov.translate.goog/fsd/season?_x_tr_sl=en&_x_tr_tl=id&_x_tr_hl=id&_x_tr_pto=tc

Class: XI AKL 1

Absent number : 31

Tsunamis, one of the most destructive natural disasters, are triggered by sudden movements in the Earth's crust beneath the ocean.

Tsunamis occur when a major fault under the ocean floor suddenly slips. The displaced rock pushes water above it like a giant paddle, producing powerful water waves at the ocean surface. These waves spread out from the earthquake source and travel across the ocean until they reach the coastline. As they approach the coastline, their height increases, particularly as they encounter the continental shelf, the sloping part of the Earth's crust rising from the ocean floor to the land. Tsunamis bring about catastrophic consequences, including severe flooding, loss of lives due to drowning, and extensive damage to property.

These immense sea waves, generated by disturbances such as earthquakes, landslides, or volcanic eruptions, remain undetectable far out in the ocean. However, once it reaches shallow water, this fast traveling wave grows very large.

https://www.sonora.id/read/424071741/3-contoh-explanation-text-singkat-tentang-bencana-alam-dan-strukturnya

Class: XI AKL 1

Absen: 19

A total lunar eclipse occurs when the entire surface of the Moon enters the Earth's inner shadow (umbra). This phenomenon can only occur when the Moon is full and the Sun, Earth, and Moon are in a straight line.

The process of a total lunar eclipse begins when the Moon moves into Earth's penumbra shadow. At this stage, the sunlight hitting the Moon begins to decrease, making its surface appear slightly dimmer. After that, the Moon moves further and further into the umbra shadow, the Earth's dark inner shadow. The Sun's light is completely blocked by the Earth.

When the Moon is completely within the umbra, the sight is truly stunning. The Moon doesn't simply disappear; instead, it appears copper-red, often called a "blood moon." This red color occurs because sunlight passing through Earth's atmosphere is refracted and filtered. Earth's atmosphere absorbs blue and green wavelengths of light, while red light is transmitted and reflected back toward the Moon. This is why the Moon appears red during a total eclipse.

This phenomenon usually lasts for several hours, from the time the Moon enters the penumbra until it finally exits. A total lunar eclipse can be observed with the naked eye without special equipment, unlike a solar eclipse, which requires protection. The beauty of a total lunar eclipse is often a rare moment eagerly awaited by many people around the world.

A total lunar eclipse occurs when the entire surface of the Moon enters the Earth's inner shadow (umbra). This phenomenon can only occur when the Moon is full and the Sun, Earth, and Moon are in a straight line.

Link 👇🏻

https://mediaindonesia.com/humaniora/737377/3-contoh-teks-eksplanasi-gerhana-bulan#goog_rewarded

Class : XI AKL 1

Number : 35

Aurora is a stunning natural phenomenon that occurs around the Earth’s North and South Poles. The aurora seen in the north is called Aurora Borealis, while the one seen in the south is called Aurora Australis.

According to NASA, auroras are caused by collisions between high-speed electrons from outer space and atoms and molecules such as oxygen and nitrogen in the Earth’s upper atmosphere. These electrons come from the magnetosphere, a region of space influenced by the Earth’s magnetic field.

When electrons transfer their energy to oxygen and nitrogen, these gases become “excited.” As they return to their normal state, they release energy in the form of photons, which are particles of light. This light appears at altitudes of about 100 to over 400 km above the Earth’s surface. When many electrons collide with the atmosphere, the emitted light becomes brighter and can be clearly seen from Earth, creating a spectacular aurora display.

Thus, auroras are the result of interactions between charged particles from outer space and the Earth’s atmosphere, producing dazzling light displays in the polar skies.

Link:

https://www.detik.com/sumut/berita/d-7360985/bagaimana-proses-terbentuknya-aurora-ini-penjelasannya/amp

Class : XI AKL 3

Absent Number : 35

"Photosynthesis is the process by which plants, algae, and some bacteria convert light energy from the sun into chemical energy in the form of glucose.

This process occurs in specialized organelles called chloroplasts, which contain the pigment chlorophyll. Chlorophyll absorbs light energy, which is then used to convert carbon dioxide and water into glucose and oxygen."

Class : XI AKL 1

Absent number : 25

The sky appears blue to our eyes because of a phenomenon called Rayleigh scattering. When sunlight enters the Earth’s atmosphere, it collides with molecules of air and tiny particles. Sunlight, although it looks white, is actually made up of different colors, each with a different wavelength.

Colors with shorter wavelengths, such as blue and violet, are scattered more in all directions by the gases and particles in the atmosphere. Even though violet light is scattered the most, our eyes are more sensitive to blue light, and the upper atmosphere absorbs some violet light. As a result, we perceive the sky as blue during the day.

During sunrise and sunset, the sky often appears red, orange, or pink. This happens because the sun is lower on the horizon and its light passes through a thicker layer of the atmosphere. The shorter blue wavelengths are scattered away, leaving the longer red and orange wavelengths to dominate.

In conclusion, the color of the sky is determined by how sunlight interacts with the Earth’s atmosphere. Rayleigh scattering makes the daytime sky look blue and the sunrise or sunset appear red and orange.

Class : XI AKL 1

Number : 30

​Purring is a distinctive sound often made by cats, and it's not just a sign of happiness. First, a cat's purr is produced by a series of rapid vibrations of muscles around the cat's voice box (larynx). Then, these vibrations occur as the cat inhales and exhales, causing the small, flexible hyoid bone in its throat to vibrate. Next, these vibrations produce the purring sound that we hear. Finally, cats use purring not only to show comfort and contentment, but also as a self-healing mechanism, a way to reduce stress, and to communicate with their mother or owner.

This information comes from general scientific knowledge about cat behavior, which can be found on various pet and veterinary websites. One of the sources is an article from "the Halodoc" website.

Class : XI AKL 1

Absent Number : 33

Aurora or polar light is a natural phenomenon in the form of colorful light beams that appear to dance in the night sky in the Earth’s ionosphere layer. This phenomenon occurs due to the interaction between the Earth’s magnetic field and charged particles emitted by the sun through the solar wind.

The sun emits a stream of charged particles called plasma through the solar wind. This plasma consists of high-energy electrons and protons that can escape the sun’s gravity due to extremely high temperatures. When approaching the Earth, these particles are drawn by the magnetic field concentrated at the north and south poles. When colliding with atmospheric particles of the Earth, such as oxygen and nitrogen, excitation and relaxation processes of electrons occur, producing colorful light beams in the night sky.

Therefore, auroras can only be clearly seen around the Earth’s poles, namely the Aurora Borealis in the north pole and the Aurora Australis in the south pole. This phenomenon is one of the natural beauties that can only be enjoyed in regions far from the equator, such as in New Zealand or Norway.

Class : XI AKL 1

No. Absen : 03

The blue flame at Ijen Crater is a rare natural phenomenon found in Banyuwangi, East Java. This phenomenon occurs because hydrogen sulfide gas (H₂S) escapes through cracks in the volcano at extremely high temperatures, sometimes reaching more than 600 degrees Celsius. When this gas meets sulfur and oxygen in the air, it immediately burns and produces a glowing blue fire. The color blue appears because the combustion temperature is very high, unlike ordinary fire that looks red or orange. The flame can only be seen clearly in the darkness of the night.

The existence of this blue flame is also related to the geological history of Mount Ijen. Around 300,000 years ago, the Ancient Ijen stratovolcano was formed. Then about 70,000 years ago, a massive eruption caused the volcano to collapse and created a 15-kilometer wide caldera. Inside this caldera lies the Ijen Crater, which is still active today and continuously emits volcanic gases. These gases, combined with high pressure and heat, make the blue flame possible.

Therefore, the blue flame at Ijen Crater is not just a tourist attraction but also evidence of powerful natural processes beneath the earth. It shows how volcanic activity, sulfur gas, and extreme heat interact to create one of the most unique natural wonders in the world.

link :

https://www.detik.com/jatim/berita/d-6505019/sejarah-blue-flame-kawah-ijen-yang-tak-bisa-dinikmati-saat-status-waspada

Class : XI AKL 1

Number : 36

On a dark and silent night, a flash of light fell from the sky, it was a shooting star, which appeared only for a moment, but left an indescribable sense of awe.

The process of a shooting star begins with Earth's rotation and passing through a cluster of space particles that share the same orbit as Earth. These particles, which are close to Earth, are then attracted to the Earth's atmosphere. This occurs due to the very strong gravitational force. Space particles attracted to the Earth's atmosphere will rub against the Earth's atmosphere. After rubbing against the Earth's atmosphere, these particles will accelerate to the mesosphere, causing even greater friction. This also causes their speed to increase. By the time they reach Earth's sky, the particles have burned up, producing the light we often see as shooting stars.

So, shooting stars are a phenomenon where space particles are attracted by Earth's gravity and then rub against the atmosphere, burning up and appearing bright in the sky. Besides being beautiful to look at, their presence is useful as objects of scientific research, helping to understand the origins of the solar system and the dynamics of the universe.

Source : https://adjar.grid.id/read/543896589/bagaimana-proses-terjadinya-bintang-jatuh

Class: XI AKL 3

Number: 15

First, bees fly from flower to flower to collect nectar, a sweet liquid made by plants. Then, they store the nectar in their special honey stomach, where enzymes begin breaking down the sugars. Next, the bees return to their hive and pass the nectar to other worker bees, who continue the process and place it into the honeycomb. Finally, the bees fan their wings to evaporate excess water from the nectar, turning it into thick, golden honey that is rich in sugars, vitamins, and minerals.

https://www.honeyflow.com/blogs/beekeeping-basics/how-do-bees-make-honey?srsltid=AfmBOorag3Lwh6UWNYYVVdP74rwhSUjRIGjKIQKpVemhzmtMOcwb8OMm

Class: XI AKL 3

Absen: 34

Volcanoes do not erupt spontaneously-they are the culmination of a long geological process that takes place deep within the earth.

The process of volcanic eruption is initiated by the accumulation of magma beneath the Earth's surface. Magma forms due to the extreme temperature and pressure of the Earth's interior.

Then, high-pressure gases mix with the magma. When the next trap breaks, the magma is pushed up towards the surface through cracks in the Earth's crust.

Eruptions occur when the pressure is too high, forcing the magma out as lava and producing various materials such as volcanic ash, hot gases, and molten rock.

Volcanic eruptions are dramatic processes that combine pressure, heat and earth materials in one big event. Studying this process not only teaches us about nature, but also warns us about the powerful forces hidden within the earth.

https://tirto.id/proses-terjadinya-gunung-meletus-penyebab-dan-tanda-tandanya-hboz?

Class: XI AKL 1

No : 15

A tornado is a natural disaster that is caused by a violently rotating column of air. It is formed from a cumulonimbus cloud and it is known for producing severe destruction in a very short time.

Warm air is lifted upward and cold air is pushed downward inside a cumulonimbus cloud. Because of this interaction, a vortex is created in the atmosphere. Then, the vortex is strengthened and condensation is produced. As a result, a funnel-shaped cloud is formed and its spiral rotation can be seen clearly from the ground.

When the funnel is pulled downward and touches the Earth’s surface, a tornado officially occurs. Houses are destroyed, trees are uprooted, and heavy objects are thrown away by the powerful wind. If the rotation is very wide and lasts for a long distance, the tornado becomes extremely destructive. In some cases, wind speeds are recorded at more than 400 kilometers per hour.

A tornado is formed through a series of atmospheric processes that involve rising warm air and descending cold air. Because serious damage is caused by tornadoes, early warning systems are needed to reduce disaster

risk.

source : https://id.m.wikipedia.org/wiki/Angin_puting_beliung

Class : XI AKL 1

Number : 32

A solar eclipse is a natural phenomenon that occurs when the moon passes between the Earth and the sun, partially or completely blocking sunlight. This rare event can only occur during the new moon phase, when the sun, moon, and Earth are aligned in a straight line.

First, the moon orbiting Earth sometimes positions itself directly between the Earth and the sun. When this happens, the moon's shadow falls on the Earth's surface, making the sun appear obscured. There are four types of solar eclipses: total, partial, annular, and hybrid. A total solar eclipse occurs when the moon completely obscures the sun. A partial eclipse only partially obscures the sun's surface. An annular solar eclipse occurs when the moon is farther from Earth and appears smaller, thus not completely obscuring the sun, forming a "ring of fire." A hybrid solar eclipse occurs when the moon is directly between the sun and Earth. At the peak of the solar eclipse, the sun will appear as a ring in one location. In other locations, the sun will appear as if it is completely obscured by the moon. This phenomenon lasts only a few minutes because the Earth and the moon are constantly moving. This is why solar eclipses are considered rare and special events.

In conclusion, a solar eclipse occurs when the moon, sun, and Earth align, causing the moon's shadow to obscure the sun's light. This event shows how amazing natural phenomena are in outer space.

Kenali Macam-macam Gerhana dan Perbedaannya https://share.google/XBDb0wDvJvOkmZe76

Class : XI AKL 1

Number : 20

A tsunami is a series of extremely long waves caused by a large and sudden displacement of the ocean, usually the result of an earthquake below or near the ocean floor. This force creates waves that radiate outward in all directions away from their source, sometimes crossing entire ocean basins.

First Activation.

A tsunami begins far offshore, with an earthquake, volcanic eruption or landslide. The sudden movement on the seabed displaces the water above it. Although the vertical movement may initially be less than a metre, it covers a large area and the total volume of water displaced is huge.

Second Build.

In deep water, the wave spreads out rapidly. The wave may only be 30cm high at this point and hard to spot, but it travels at more than 800km per hour. Unlike normal, wind-driven waves, which are spaced about 100m apart, there can be up to 200km between successive tsunami wave crests.

Third Formation.

Each wave has a peak and a trough, and sometimes the trough of a tsunami reaches land before the peak. This causes a drawback where the tide seems to go out hundreds of metres further than usual. This drawback lasts for about six minutes before the peak reaches shore, and can catch people out.

Fourth Approach.

As the wave crest reaches shallower water, friction with the seabed causes it to slow down. The faster water arriving behind it piles in and pushes the wave crest much higher. The wave height will continue to increase over the next six minutes.

Fifth Impact.

Most tsunamis do not have a breaking wave crest, instead they resemble a fast incoming tide. This can push incredible volumes of water up to a kilometre inland, sweeping up people, trees, cars and small buildings in their path. In the next drawback, people and objects can get swept out to sea.

A tsunami is a large ocean wave generated by an earthquake, volcanic eruption, or landslide on the seabed. These waves move very quickly in the middle of the ocean but don't appear tall. As they approach the shore, they slow down but become taller and more dangerous. Sometimes the sea recedes long before a large wave arrives. When it reaches land, a tsunami can sweep away houses, cars, trees, and even people nearby.

Links:

https://www.noaa.gov/education/resource-collections/ocean-coasts/tsunamis#:~:text=A%20tsunami%20is%20a%20series,sometimes%20crossing%20entire%20ocean%20basins.

https://www.sciencefocus.com/planet-earth/how-do-tsunamis-form

Number : 28

Class : XI AKL 1

Photosynthesis is an essential process in which plants, especially those containing chlorophyll, are able to produce their own food with the help of sunlight. This process is very important because it forms the basis of survival for plants and other living things on Earth.

In photosynthesis, several things are required. First, water is absorbed by the roots from the soil and then transported to the leaves. Meanwhile, carbon dioxide enters through the stomata, which are small pores on the underside of the leaves. Then, sunlight is captured by chlorophyll in the leaves to trigger a chemical reaction. As a result, water and carbon dioxide are converted into glucose and oxygen. Glucose functions as a source of energy, either used directly or stored as food reserves such as starch. At the same time, oxygen is released into the air through the stomata and is very useful for living beings, including humans.

Photosynthesis itself takes place in two main stages. The first stage is the light reaction, which depends on sunlight, occurs in the grana, and produces ATP and NADPH. The second stage is the dark reaction, or Calvin cycle, which does not depend on light. In this stage, ATP and NADPH are used to bind CO₂, resulting in the formation of glucose as well as the regeneration of RuBP.

In conclusion, photosynthesis is not only the process by which plants produce food, but it is also the key to maintaining the balance of ecosystems on Earth. Through this process, plants not only meet their own energy needs but also release oxygen, which is vital for the survival of all living beings.

Links :

•https://www.detik.com/edu/detikpedia/d-5750187/pengertian-fotosintesis-dan-prosesnya-pada-tumbuhan/amp

Class : XI AKL 3

No : 01

Why Acid Rain Happens

Acid rain is a type of rainfall with a pH level lower than 5.7, making it more acidic than normal rain. This phenomenon can cause severe damage to the environment, living organisms, and even buildings and historical monuments.

Acid rain occurs due to the reaction of sulfur dioxide (SO₂) and nitrogen oxides (NOₓ) with water vapor in the atmosphere. These gases are mainly released from industrial activities, burning fossil fuels, and vehicle emissions. When SO₂ and NOₓ rise into the atmosphere, they mix with water, oxygen, and other chemicals to form sulfuric acid (H₂SO₄) and nitric acid (HNO₃). The acids are then carried by clouds and eventually fall to the Earth’s surface as acid rain.

The phenomenon of acid rain clearly shows the harmful impact of air pollution on the planet. It damages forests, pollutes water sources, kills aquatic life, and weakens man-made structures over time. This serves as a reminder that human activities significantly affect nature, and reducing pollution is essential to protect both the environment and future generations.

https://id.wikipedia.org/wiki/Hujan_asam

https://www.detik.com/edu/detikpedia/d-6967966/mengenal-hujan-asam-penyebab-proses-terjadi-hingga-cara-mencegahnya

Number : 22

Class : XI AKL 1

Unemployment refers to people who do not work at all, are looking for jobs, work less than two days a week, or are trying to obtain a proper job. This phenomenon is a social problem faced by many countries, including Indonesia.

Unemployment occurs due to several factors. First, technological advancement makes many companies switch to machines and robots, reducing the need for human labor. Second, the low level of education and skills causes some people to not meet the criteria set by companies.

Third, the imbalance between the number of job opportunities and the large workforce creates fierce competition. Fourth, globalization also plays a role, as some foreign companies tend to prefer workers from their own countries. Lastly, layoffs (termination of employment) worsen the rise in unemployment. In addition, poor economic conditions and unsupportive government policies can slow down the creation of new job opportunities.

Thus, unemployment arises from a combination of internal and external factors. To overcome this issue, it is necessary to improve skills, create new job opportunities, and provide worker protection so that social welfare can be maintained.

https://masuk-ptn.com/artikel/detail/banyaknya-pengangguran-diindonesia

https://id.m.wikipedia.org/wiki/Pengangguran

Class: XI AKL 1

Absent Number: 18

Chili peppers are famous for their burning, hot sensation. Interestingly, this “heat” is not a real temperature increase but a signal created by a chemical in the chili.

Inside chili peppers there is a compound called capsaicin, found mainly in the white membrane that holds the seeds. When someone eats chili, capsaicin attaches to TRPV1 receptors (Transient Receptor Potential Vanilloid 1) on nerve endings in the tongue and mouth. These receptors normally detect real heat or tissue damage. By binding to them, capsaicin tricks the nerves into sending a message of heat and pain to the brain.

The brain interprets this as burning even though nothing is actually on fire. Scientists call this a chemesthetic response because our nerves respond as if there is harm even when it is only a chemical. Capsaicin can also trigger the release of endorphins, natural painkillers that create a small feeling of pleasure or excitement, which is why some people enjoy spicy foods.

The body reacts to this false heat by sweating, tearing, flushing, and speeding up heart rate or metabolism. How hot a chili feels depends on the amount of capsaicin, measured on the Scoville Heat Scale. Bell peppers have almost no capsaicin, while peppers like Carolina Reaper contain extremely high levels, causing intense heat. From an evolutionary view, this spiciness may help chili plants protect their seeds. Mammals are discouraged from eating too many fruits, while birds, which spread the seeds, are unaffected because their TRPV1 receptors do not respond to capsaicin.

The spiciness of chili is not a real taste but a pain-like signal. Capsaicin activates heat receptors in the mouth, and the brain interprets it as burning, giving chili its unique fiery sensation.

https://rri.co.id/lain-lain/1098210/mengapa-cabe-memiliki-rasa-pedas-ini-penjelasan-ilmiahnya

https://www.brainacademy.id/blog/pedas-bukan-rasa-tapi-sensasi-panas

https://www.idntimes.com/science/discovery/bagian-cabai-menyebabkan-sensasi-pedas-c1c2-01-qclsg-j2hdz0

Class : Xl AKL 3

Number : 12

Globalization is a worldwide process related to social order. It can happen in almost all aspects of human life, such as social, politics, culture, knowledge, ideology, economy, and especially technology.

Technology is a very important factor in globalization, especially in the field of communication and information. The technology includes mobile phones, television, radio, and the internet. With internet access, people around the world can easily get information, so many international transactions can happen more easily.

People are also helped in getting goods or exporting them abroad. Globalization also makes it easier to create economic cooperation and international agreements.

Besides the positive effects, unfortunately, globalization also brings negative effects, such as the entry of foreign cultures that can influence people’s lifestyle and reduce local culture and love for the homeland.

Therefore, as wise citizens, we need to filter the information that comes in, so it will not cause negative impacts and harm society.

Class : XI AKL 1

Number : 04

The sea can be defined as a vast body of salt water. Generally, this body of salt water submerges land to the point where it divides it into continents or islands.

Seawater is essentially colorless and transparent like ordinary water. However, when viewed from a distance, it appears dark blue or light blue.

The blue color of seawater comes from sunlight, which has a long wavelength. Seawater appears blue because of the interaction between sunlight and water molecules as well as dissolved particles, such as salt or fragments of dead organisms.

These particles reflect some of the light before it has time to scatter the actual blue color. Furthermore, the light scattered from the sea is usually bluish-green.

Thus, the blue color of the sea does not come from the water itself, but from sunlight that is reflected and scattered by molecules and particles in the seawater.

https://kumparan.com/ragam-info/kenapa-air-laut-berwarna-biru-ini-alasannya-22Rbkg8ZqZR

https://nationalgeographic.grid.id/amp/132209929/mengapa-air-laut-berwarna-biru-ini-penjelasannya-menurut-sains?page=2

Class : Xl AKL 1

Number : 08

Rainbow is a natural phenomenon that is caused by the light refraction and reflections in the water drops, resulting in a spectrum of light appearing in the sky. A rainbow appears as a colorful arch. When they are caused by water and the sun, a rainbow shows up on the side of the sky that is directly facing the sun. They can become a complete loop at times, but for the average observers, only the arc will be seen.

The colors in the rainbow will be the ones that can be found within the white light color spectrum as it divides. There are 7 main colors that you can see in the Rainbow which are red, orange, yellow, green, blue, indigo and violet. When the sunlight touches the water droplets, 7 colors emerge. When sunlight moving from air to water, the light colors are slowed down to various speeds - depends on their frequency. As purple light enters the raindrops, it bends at a sharp angle. On the right side of the water droplet, some light is passed back into the air, while the rest bounces back. Raindrops higher in the sky scatter the light so that only red light is visible to the observer's eyes. Droplets between red and violet reflect different colors, so the observer sees the full spectrum of colors.

Sunlight striking rain in the atmosphere is refracted at the surface of the raindrop and enters the droplet. After refraction occurs, the light breaks into seven colors inside the raindrop; it is then reflected to the other side of the raindrop after traveling inside it. When the light in the raindrop refracts, a spectrum is formed to make the 7 colors of the rainbow appear. During reflection, the angle (reflection) is equal to the angle of incidence; this means that the reflected light travels along a set path and maintains the difference in the angle of refraction. A rainbow is a set of raindrops suspended in the atmosphere that divides sunlight into 7 colors, like a prism.

https://www.kompasiana.com/amp/annisanadya2004/647cbf858221991022758c92/explanation-text-how-is-rainbow-formed

Class : XI AKL 1

Number absent : 07

Rainbow 🌈 🌈

A rainbow is a natural phenomenon that appears in the sky as a beautiful arc of colors after rain. It happens because of light refraction, reflection, and dispersion.

First, when sunlight passes through raindrops in the air, the light bends or refracts. Then, the light is reflected inside the raindrop. As the light comes out, it is refracted again and separated into different colors. This process is called dispersion. The colors appear in a specific order: red, orange, yellow, green, blue, indigo, and violet.

Therefore, a rainbow appears because sunlight interacts with water droplets in the atmosphere, creating a spectrum of colors.

Class : XI AKL 3

Number : 17

Star formation is a process that happens inside dense regions of molecular clouds in interstellar space. These regions, often called stellar nurseries, collapse under gravity and give birth to new stars. Astronomers study the interstellar medium, molecular clouds, protostars, and young stars to understand this process, which is also related to planet formation.

First, low-mass stars form through the gravitational collapse of rotating gas and dust in molecular clouds. This collapse creates an accretion disk, where material flows into the central protostar until it becomes a star. This theory is well supported by observations.

Then, the formation of high-mass stars is more complex. Massive stars release strong radiation that pushes surrounding matter away. In the past, scientists thought this radiation pressure could stop accretion and prevent the growth of very massive stars.

Next, new theories suggest that jets and outflows from massive protostars create cavities. These cavities allow radiation to escape while accretion continues through the disk. This means that high-mass stars may form in a way similar to low-mass stars.

There is also evidence that some massive protostars are surrounded by accretion disks. Other theories propose different mechanisms. One of the most popular is competitive accretion, which explains that massive protostars compete with smaller ones to gather material from the parent molecular cloud.

Finally, another possibility is that massive stars can form through the merging of two or more low-mass stars. In conclusion, the formation of low-mass stars is well understood, while the process of high-mass star formation is still under study.

Link :

https://id.wikipedia.org/wiki/Pembentukan_bintang

Class : XI AKL 1

Number : 23

A solar eclipse is a natural phenomenon that occurs when sunlight is blocked by the moon, preventing it from reaching Earth. This event usually happens during the day. When a solar eclipse takes place, a bright and sunny day can suddenly turn dim, or even dark, despite clear skies.

A solar eclipse occurs because the moon is positioned between the Earth and the sun, causing the sun’s light to be partially or completely blocked. On average, solar eclipses happen every 18 months, but they are only visible in specific regions depending on the path of the eclipse.

There are four types of solar eclipses:

1. Total Solar Eclipse – Occurs when the moon completely covers the sun, making the sun’s corona visible. This can only be seen from a narrow path on Earth.

2. Annular Solar Eclipse – Happens when the moon is directly in front of the sun but appears smaller, forming a bright ring of sunlight around it.

3. Hybrid Solar Eclipse – A rare type that shifts between total and annular, depending on the viewer’s location on Earth.

4. Partial Solar Eclipse – Occurs when the moon only partially covers the sun. It is more common and usually seen outside the path of total or annular eclipses.

Although a solar eclipse is a rare and fascinating event, it should not be viewed directly without proper eye protection. Ultraviolet B rays from the sun can damage the retina. Therefore, people are advised to use optical filters certified with ISO 12312-2:2015 when observing a solar eclipse.

A solar eclipse is a valuable natural event and should not be missed. However, the public must follow expert guidelines to enjoy this phenomenon safely and avoid harm.

https://id.m.wikipedia.org/wiki/Gerhana_matahari

https://id.pinterest.com/pin/602356518896558023/

Class : XI AKL 1

No Absen : 13

A tornado is a very strong whirlwind that connects cumulonimbus clouds with the surface of the earth. The average speed of a tornado reaches 177 km/h, and it can even reach speeds of 300–480 km/h with a width of up to 1.6 km and a path length of more than 100 km. This phenomenon commonly occurs in the United States, Canada, Latin America, Europe, South Africa, Australia, and New Zealand, especially during the transitional season.

The process of tornado formation goes through three phases. First, the growing phase, where upward air currents rise to the top of the cloud and trap water droplets and ice crystals, so rain has not yet fallen. Second, the mature phase, when rain begins to fall causing friction between the upward and downward air currents. The difference in air temperature creates a strong vortex that eventually touches the earth’s surface, usually accompanied by heavy rain. Lastly, the dissipating phase, which occurs when the upward air currents weaken, the rain stops, and the tornado vortex disappears.

Thus, a tornado is the result of a complex atmospheric process in cumulonimbus clouds. Although it does not occur everywhere, tornadoes are known as one of the most dangerous natural disasters due to their great power and destructive capability.

https://www.kompas.com/skola/read/2022/10/07/120000469/tornado--pengertian-ciri-ciri-dan-proses-terjadinya

Class: XI AKL 3

NO: 18

We all agree that the snowfall is always fascinating. In the snowfall, all people stay out of the house and play with the snow. People can make giant snowmen, trample along the snow, or play with snowballs with their families. However, are you curious about how snow is made?

Snow is water droplets falling from the clouds. These droplet waters then become solid and create snow. It happens because rain consists of water vapor particles being cooled in the air.

Snow happens when water vapor piled up in the earth’s atmosphere freezes. It happens before they turn into water droplets. This process occurs when the temperature in the cloud becomes very frigid.

Snowflakes are created by crystals of ice that have established around a little filth in the air. They then grow from small forms into big one. The form of snowflakes is varied. They can consist of 200 crystals maximum.

•https://www.bola.com/ragam/read/5172067/4-contoh-explanation-text-dan-terjemahannya-sumber-referensi-belajar

Class : XI AKL 3

Number : 01

Acid rain is a type of rainfall with a pH level lower than 5.7, making it more acidic than normal rain. This phenomenon can cause severe damage to the environment, living organisms, and even buildings and historical monuments.

Acid rain occurs due to the reaction of sulfur dioxide (SO₂) and nitrogen oxides (NOₓ) with water vapor in the atmosphere. These gases are mainly released from industrial activities, burning fossil fuels, and vehicle emissions. When SO₂ and NOₓ rise into the atmosphere, they mix with water, oxygen, and other chemicals to form sulfuric acid (H₂SO₄) and nitric acid (HNO₃). The acids are then carried by clouds and eventually fall to the Earth’s surface as acid rain.

The phenomenon of acid rain clearly shows the harmful impact of air pollution on the planet. It damages forests, pollutes water sources, kills aquatic life, and weakens man-made structures over time. This serves as a reminder that human activities significantly affect nature, and reducing pollution is essential to protect both the environment and future generations.

https://id.wikipedia.org/wiki/Hujan_asam

https://www.detik.com/edu/detikpedia/d-6967966/mengenal-hujan-asam-penyebab-proses-terjadi-hingga-cara-mencegahnya

Kelas : XI AKL 3

absen : 25

An earthquake is a sudden shaking of the ground caused by the movement of tectonic plates beneath the Earth’s surface. These plates can press, slide, or collide with each other. When too much pressure builds up, the energy is released in the form of seismic waves, causing the Earth to shake.

Earthquakes are common near tectonic plate boundaries, like in Indonesia. Their strength is measured using the Richter scale or Moment Magnitude Scale. Small earthquakes may not be felt, but stronger ones can damage buildings and cause injuries.

Although earthquakes cannot be predicted, people can prepare by learning safety procedures and building earthquake-resistant structures. Understanding how earthquakes work helps reduce their impact.

Name : Gesya Vina Ramadani

Class : XI AKL 3

Absent Number : 16

The ocean is home to many powerful forces, and one of the most fascinating is the whirlpool, also known as a maelstrom. A whirlpool is a swirling body of water that forms a vortex, pulling objects towards its centre.

Whirlpools are created when strong currents meet obstacles such as narrow straits, rocky seabeds, or when opposing tidal flows collide. This concentration of energy causes the water to twist and churn violently. The Earth’s rotation also influences the direction of the spin: counter-clockwise in the Northern Hemisphere and clockwise in the Southern Hemisphere.

One of the most powerful maelstroms in the world is the Saltstraumen in Norway. Every six hours, about 400 million cubic metres of water rush through a narrow channel, producing currents that reach more than 40 kilometres per hour. Other famous whirlpools include the Moskstraumen in Norway, the Corryvreckan in Scotland, the Old Sow in Canada, and the Niagara Whirlpool in North America.

Throughout history, whirlpools have inspired myths and legends. They were once feared as sea monsters capable of swallowing entire ships. While they can be dangerous—especially for small boats—their true impact is more about powerful turbulence than total destruction. Today, these natural phenomena continue to amaze scientists, sailors, and tourists alike as dramatic displays of the ocean’s strength.

Source : https://geographical.co.uk/news/phenomena-maelstroms-and-whirlpools

Class : XI AKL 3

Absent number : 20

Aurora Borealis: Nature’s Light Show

The Aurora Borealis, or Northern Lights, is a spectacular natural light display that occurs mainly in regions close to the Arctic Circle. These glowing patterns often appear as curtains or arcs of green, red, or purple light moving gracefully across the sky. The name comes from the Latin words aurora (dawn) and borealis (northern), describing the phenomenon that is most often seen in the northern hemisphere.

The Northern Lights are caused by interactions between charged particles from the Sun and Earth’s magnetic field. When solar wind or powerful bursts of solar energy, such as coronal mass ejections, reach our planet, these particles are guided by the magnetic field toward the poles. As they collide with gases in the upper atmosphere, they release energy in the form of light.

Different gases and altitudes produce different aurora colors. Oxygen around 100–200 km above Earth produces green light, while higher oxygen levels may create red glows. Nitrogen, on the other hand, can cause blue or purple hues. These colors depend on how the atoms and molecules release energy after being excited by incoming solar particles.

Aurora displays are not static, they can change shape, brightness, and speed. Their intensity is strongly influenced by solar activity. During solar storms, the auroral oval expands, allowing people in lower latitudes to witness the Northern Lights. These storms can make the aurora brighter, more colorful, and more dynamic.

For centuries, the Aurora Borealis has fascinated people and inspired myths. In Finnish folklore, it is called “fox fire,” while Inuit legends describe it as spirits playing in the sky. Today, the Northern Lights are admired not only for their cultural meaning but also as a breathtaking reminder of the connection between Earth and the Sun.

source:

https://en.m.wikipedia.org/wiki/Aurora

https://www.swpc.noaa.gov/content/aurora-tutorial

https://www.nhm.ac.uk/discover/what-are-the-northern-lights-aurora-borealis-causes-explained

https://www.rmg.co.uk/stories/space-astronomy/what-causes-northern-lights-aurora-borealis-explained

Kelas: XI AKL 3

No: 07

A rainbow is a natural optical phenomenon that appears as a colorful arc in the sky, usually seen after rainfall, when sunlight encounters countless tiny droplets in the atmosphere. It forms because white sunlight undergoes refraction, internal reflection, and dispersion within each raindrop, resulting in the separation of light into its constituent colors: red, orange, yellow, green, blue, indigo, and violet.

As light enters a droplet, it bends (refraction), reflects off the back surface, and bends again when it exits. Because light of different wavelengths refracts by different amounts—shorter wavelengths (blue/violet) bend more than longer ones (red)—the colors spread out in sequence.

The distinctive circular arc of a rainbow appears because only light exiting the droplets at a precise angle—around 42° from the direction opposite the Sun—reaches the observer's eye with maximum brightness.

Occasionally, a secondary rainbow appears above the primary one. It forms through two internal reflections inside the droplets, causing reversed color order (red on the inner edge, violet outermost), and is typically dimmer. The angular radius of this secondary arc is about 50–51°.

In reality, rainbows are full circles, but from the ground, we usually only see a semicircle because the lower part lies below the horizon—unless you're high above the ground (like in an airplane), where full-circle rainbows can be seen.

Source:

https://en.m.wikipedia.org/wiki/Rainbow

https://education.nationalgeographic.org/resource/rainbow

Class : XI AKL 3

Number : 23

How the Milky Way Galaxy Formed

First, billions of years ago, clouds of gas and dust in space started to come together because of gravity. Then, these particles slowly gathered and formed large groups of stars, gas, and other cosmic materials. Next, the strong pull of gravity kept everything bound together and began shaping the galaxy. After that, many stars were born inside the galaxy, while old stars continued to move around its center. In addition, the galaxy developed a spiral shape with bright arms full of stars, gas, and planets.

As a result, our Solar System also became a part of this huge spiral galaxy. Finally, the Milky Way continues to grow and change over time as stars are born and die within it.

link : https://pasla.jambiprov.go.id/galaksi-bima-sakti-proses-terbentuk-dan-fakta-unik/

Class : XI AKL 1

Number : 17

A lunar eclipse blood moon is a natural event when the moon looks red during a total lunar eclipse. This happens because Earth blocks sunlight and only certain colors of light reach the moon.

First, the Earth moves between the sun and the moon so that its shadow covers the full moon. Then, sunlight passes through Earth’s atmosphere and gets scattered. Next, blue light is filtered out, while the longer red and orange light continues to the moon. Finally, the moon shines with a deep red or coppery color that we call a blood moon.

So, this amazing event can only happen on Earth, and it will not last forever because the moon is slowly drifting away. The color can also look darker or brighter depending on dust, smoke, or pollution in the atmosphere.

Source :

space.com-lunar-eclipse-blood-moon

Class: XI AKL 3

Number: 28

The Photosynthesis Process

Photosynthesis is a biological process in which organisms such as plants, algae, and cyanobacteria convert light energy into chemical energy. Specifically, they use sunlight to transform carbon dioxide and water into carbohydrates and release oxygen as a byproduct. This process is essential for life on Earth, as it provides both organic matter and the oxygen that most organisms require.



Photosynthesis occurs in chloroplasts within plant cells. It comprises two main phases: light-dependent reactions, which capture sunlight to produce energy carriers (ATP and NADPH), and the Calvin cycle (light-independent reactions), which uses these to fix CO₂ into sugars like glucose. 

During the light-dependent reactions, chlorophyll absorbs photons, which excites electrons that then move through an electron transport chain, generating ATP and reducing NADP⁺ to NADPH. Simultaneously, water molecules are split, releasing oxygen gas. 

In the Calvin cycle, CO₂ is incorporated into organic molecules through a series of enzyme-mediated steps. Utilizing ATP and NADPH from earlier reactions, the carbon is fixed and converted into carbohydrates—primarily glucose—which plants use as energy reserves and building components. 

Photosynthetic pigments, such as chlorophyll, are arranged within photosystems located in the thylakoid membranes of chloroplasts. These pigments capture light and initiate energy transfer. The two main photosystems are Photosystem II (absorbs at ~680 nm) and Photosystem I (absorbs at ~700 nm), working together in the Z-scheme electron transport pathway. 

Photosynthesis sustains life by producing the oxygen we breathe and forming the base of food webs. It also regulates atmospheric CO₂, playing a critical role in the Earth’s carbon cycle and overall climate stability. 

• en.wikipedia.org/wiki/Photosynthesis

Class : XI AKL 3

Number : 13

How’s Paper Made

Paper is one of the most important materials in human life, used for writing, printing, and packaging. The process of making paper is quite long and goes through several stages.

The process begins with pulping, where cellulose fibers are separated from wood, plants, or recycled paper. Pulp can be produced mechanically, chemically, or by recycling. After that, refining is done to improve the fiber quality, and screening removes unwanted particles.

Next is the forming stage, where pulp slurry is poured onto a moving screen to form a wet sheet. This sheet then goes through pressing to reduce water content, followed by drying with heated cylinders. Once dried, the paper goes through finishing such as smoothing, coating, and cutting into the required sizes.

In modern industry, paper is mass-produced using large machines like the Fourdrinier machine. Meanwhile, traditional handmade paper is still produced for artistic purposes, giving unique textures and decorative value.

In conclusion, paper is made through a series of processes that transform raw fibers into sheets ready for daily use. Although useful, paper production can impact the environment, so recycling and eco-friendly methods are increasingly encouraged to ensure sustainability.

Wikipedia – Papermaking: https://en.wikipedia.org/wiki/Papermaking

Deskera – Paper Manufacturing Process (How Paper Is Made): https://www.deskera.com/blog/paper-manufacturing-process-how-paper-is-made/

Class : XI AKL 3

Number : 27

Our Sun: Facts

Our Sun is a 4.5 billion-year-old yellow dwarf star – a hot glowing ball of hydrogen and helium – at the center of our solar system. It’s about 93 million miles (150 million kilometers) from Earth and it’s our solar system’s only star. Without the Sun’s energy, life as we know it could not exist on our home planet.

From our vantage point on Earth, the Sun may appear like an unchanging source of light and heat in the sky. But the Sun is a dynamic star, constantly changing and sending energy out into space. The science of studying the Sun and its influence throughout the solar system is called heliophysics.

The Sun is the largest object in our solar system. Its diameter is about 865,000 miles (1.4 million kilometers). Its gravity holds the solar system together, keeping everything from the biggest planets to the smallest bits of debris in orbit around it.

Even though the Sun is the center of our solar system and essential to our survival, it’s only an average star in terms of its size. Stars up to 100 times larger have been found. And many solar systems have more than one star. By studying our Sun, scientists can better understand the workings of distant stars.

The hottest part of the Sun is its core, where temperatures top 27 million °F (15 million °C). The part of the Sun we call its surface – the photosphere – is a relatively cool 10,000 °F (5,500 °C). In one of the Sun’s biggest mysteries, the Sun’s outer atmosphere, the corona, gets hotter the farther it stretches from the surface. The corona reaches up to 3.5 million °F (2 million °C) – much, much hotter than the photosphere.

Potential for Life

The Sun could not harbor life as we know it because of its extreme temperatures and radiation. Yet life on Earth is only possible because of the Sun’s light and energy.

Size and Distance

Our Sun is a medium-sized star with a radius of about 435,000 miles (700,000 kilometers). Many stars are much larger – but the Sun is far more massive than our home planet: it would take more than 330,000 Earths to match the mass of the Sun, and it would take 1.3 million Earths to fill the Sun's volume.

The Sun is about 93 million miles (150 million kilometers) from Earth. Its nearest stellar neighbor is the Alpha Centauri triple star system: red dwarf star Proxima Centauri is 4.24 light-years away, and Alpha Centauri A and B – two sunlike stars orbiting each other – are 4.37 light-years away. A light-year is the distance light travels in one year, which equals about 6 trillion miles (9.5 trillion kilometers).

Orbit and Rotation

The Sun is located in the Milky Way galaxy in a spiral arm called the Orion Spur that extends outward from the Sagittarius arm.

The Sun orbits the center of the Milky Way, bringing with it the planets, asteroids, comets, and other objects in our solar system. Our solar system is moving with an average velocity of 450,000 miles per hour (720,000 kilometers per hour). But even at this speed, it takes about 230 million years for the Sun to make one complete trip around the Milky Way.

The Sun rotates on its axis as it revolves around the galaxy. Its spin has a tilt of 7.25 degrees with respect to the plane of the planets’ orbits. Since the Sun is not solid, different parts rotate at different rates. At the equator, the Sun spins around once about every 25 Earth days, but at its poles, the Sun rotates once on its axis every 36 Earth days.

Source : https://science.nasa.gov/sun/facts/#hds-sidebar-nav-14

The water cycle, also known as the hydrological cycle, explains how water moves continuously around the Earth. It plays a vital role in maintaining life and the balance of nature.

The process begins with evaporation, when heat from the sun warms oceans, lakes, and rivers, turning liquid water into water vapor. Plants also contribute through transpiration, releasing water vapor from their leaves.

The vapor then rises into the atmosphere and cools, forming tiny droplets that cluster together as clouds. This stage is called condensation. When the droplets become heavy, they fall back to the Earth as precipitation in the form of rain, snow, or hail.

Once the water reaches the ground, some of it flows over the surface as runoff, eventually returning to rivers, lakes, and oceans. Another portion seeps into the soil as infiltration, replenishing underground water supplies.

Finally, the process repeats itself endlessly, ensuring that water is recycled and available for all living things. Without the water cycle, life on Earth would not be possible.

https://www.usgs.gov/special-topics/water-science-school/science/water-cycle

Class : XI AKL 3

No Absen : 26

First, volcanoes begin to form when intense heat inside the Earth melts rocks and turns them into magma. Then, this magma gathers in a chamber beneath the volcano, and pressure starts to build up. Next, when the pressure becomes too strong, the magma pushes through cracks in the Earth’s crust and rises toward the surface. Finally, it erupts as lava, ash, and gases that explode out of the volcano. This process can change the shape of the mountain, damage the environment, but also create fertile soil for plants.

1. https://www.usgs.gov/faqs/how-do-volcanoes-erupt

2. https://www.britannica.com/story/what-causes-a-volcano-to-erupt

Class : XI AKL 3

Number : 31

A volcanic eruption is one of the most powerful natural events on Earth. It happens when magma, which is molten rock stored beneath the surface, rises due to immense pressure. As this pressure increases, magma forces its way upward through cracks and openings until it reaches the Earth’s surface. When it erupts, magma becomes lava, accompanied by gases, ash, and sometimes even volcanic bombs. These eruptions can shape landscapes, create new landforms, and affect global climate.

Not all eruptions are the same. Some are effusive, producing rivers of lava that flow slowly and cover large areas, like those seen in Hawaii. Others are explosive, such as Plinian eruptions, which release massive clouds of ash, gas, and rock high into the atmosphere. Explosive eruptions are far more destructive, capable of burying cities under ash, disrupting air travel, and causing pyroclastic flows—fast-moving currents of hot gas and volcanic material that can destroy everything in their path. Despite their dangers, eruptions also provide benefits, as volcanic ash eventually breaks down into minerals that make soil extremely fertile.

Most volcanoes are located in regions where tectonic plates meet, especially along the Pacific “Ring of Fire,” an area known for frequent earthquakes and volcanic activity. Because of their unpredictable nature, scientists closely monitor volcanoes using seismographs, satellites, and gas sensors to detect warning signs of eruptions. By studying them, experts hope to reduce risks to communities living near volcanoes and provide early warnings. Although eruptions can cause devastation, they are also a reminder of the Earth’s dynamic and ever-changing nature.

Link: https://www.usgs.gov/faqs/how-do-volcanoes-erupt?utm_source=chatgpt.com

Class : XI AKL 3

Number : 04

A total solar eclipse is an event when the moon is directly between the earth and the sun, thereby blocking all of the sun's light. As a result, the day becomes as dark as night for a few minutes.

A total solar eclipse occurs when the Moon completely covers the Sun because it appears the same size in the sky. This phenomenon allows us to see the Sun's corona. The Moon's shadow consists of the umbra (total darkness, causing a total eclipse) and penumbra (dim shadow, causing a partial eclipse). The umbra on Earth is very narrow, only about 80 km, while the penumbra can be thousands of km. Due to the movement of the Moon and the rotation of the Earth, the Moon's shadow crosses the Earth to form the path of the eclipse. The total phase usually only lasts a few minutes at a location.

A total solar eclipse occurs when the Moon completely covers the Sun so that the day becomes dark for a moment. This phenomenon can only be seen in a narrow band of the umbra shadow on Earth, while the penumbra area only experiences a partial eclipse. This event lasted briefly, but allowed humans to observe the outer part of the Sun, namely the corona.

Link :

https://science.nasa.gov/eclipses/geometry/

Class : XI AKL 3

No Absen : 29

A tornado is a natural phenomenon characterized by strong, rotating winds forming a trunk-like vortex, originating from a Cumulonimbus cloud. This phenomenon occurs when hot air rising from the Earth's surface collides with cold air in the upper atmosphere. The meeting of these two air masses creates a high-speed, vertical air current.

The formation of a tornado begins with the formation of a large, tall Cumulonimbus cloud. The rapidly rising hot air creates a strong current within the cloud. When the hot and cold air meet, a vortex forms that extends downward until it reaches the ground. This vortex resembles a trunk and can suck in and blow away surrounding objects.

The impact of tornadoes is significant, including damaging homes, uprooting trees, destroying public facilities, and even threatening human life. Wind speeds within the vortex can reach 175 km/h and occur suddenly, making it difficult for the public to prepare.

To prevent a greater impact, it is important for the public to regularly monitor weather information from the BMKG (Indonesian Meteorology, Climatology, and Geophysics Agency) and heed early warnings. When a tornado occurs, immediately seek shelter in a sturdy, safe area. Disaster response education and training are also important to increase preparedness for this phenomenon.

Sumber: Scribd https://share.google/AR3bmjzBJOYbFWW1w

Class : XI AKL 3

No Absen : 03

First, a leap year is a year with 366 days, not 365. One extra day is added in February, making it 29 days. This happens because the Earth orbits the Sun in about 365 days and 6 hours. The calendar only counts 365 days, so there is a time difference. This difference keeps accumulating every year. To adjust it, the leap year was created.

Then, the six-hour difference each year will accumulate into a full day after four years. Therefore, one extra day is added to February. This system ensures that the calendar does not shift away from the Earth’s orbit. Without leap years, the calendar dates would move far from the actual seasons. With this extra day, the calendar becomes more accurate.

Next, the leap year rule is determined by a specific calculation. If a year is divisible by 400, it is a leap year. However, if it is only divisible by 100, it is not a leap year. A year divisible by 4 but not by 100 is also a leap year. This rule helps keep the calendar aligned with the Earth’s orbit.

Finally, leap years are important to maintain the balance between the calendar and nature. Without this system, seasons could shift away from the calendar. For example, the rainy season might occur in a different month. With leap years, the calendar remains accurate. Therefore, leap years are very useful for human life.

https://indonesiabaik.id/infografis/kenapa-2024-jadi-tahun-kabisat

Absen : 10

Kelas : XI AKL 3

Aurora Borealis, also known as the Northern Lights, is one of the most breathtaking natural phenomena on Earth, occurring mainly in regions near the North Pole. This mesmerizing light display paints the night sky with vibrant colors of green, purple, red, and blue. Unlike common weather events such as rain or thunderstorms, auroras are the result of complex interactions between solar energy and the Earth’s magnetic field. Understanding this rare phenomenon requires knowledge of astronomy, physics, and Earth science because it is directly linked to solar activity and space weather.

The process behind Aurora Borealis begins with the Sun. The Sun constantly emits a stream of charged particles called the solar wind, which travels through space at incredible speeds. When solar activity increases, such as during solar flares or coronal mass ejections, these particles become more intense and reach Earth in larger quantities. The Earth is surrounded by a protective magnetic field, also called the magnetosphere, which acts like a shield to block harmful radiation and charged particles. However, near the polar regions, the magnetic field lines curve downward and create openings where some particles can enter the upper atmosphere.

When the charged particles from the Sun collide with gases in the Earth’s atmosphere, they transfer energy to those gases, causing them to glow. Different gases produce different colors: oxygen at high altitudes creates red or green light, while nitrogen produces purple or blue light. The height at which these collisions happen also affects the color and brightness of the aurora. This is why auroras often appear as shimmering curtains or waves of light, constantly changing shape and color as solar particles continue to interact with the magnetic field.

Aurora Borealis is mostly visible in high-latitude areas such as Alaska, Canada, Norway, and Finland because these regions are closest to the magnetic poles. The phenomenon is best seen during the winter months when the nights are longer and skies are darker. Interestingly, there is also Aurora Australis, or the Southern Lights, which occurs near the South Pole but is less frequently observed due to the remote location of Antarctica.

In conclusion, Aurora Borealis is a rare and stunning natural event caused by interactions between solar particles and the Earth’s magnetosphere. It is not just a visual spectacle but also scientific evidence of how the Sun and Earth are connected. Understanding auroras reminds us of the vast power of space weather and the importance of Earth’s magnetic shield in protecting life. While this phenomenon may seem magical, it is actually the result of complex physical processes that occur far above our atmosphere.

Class : XI AKL 3

Number : 06

El Nino and La Nina

El Nino and La Nina are two opposite climate patterns that occur in the Pacific Ocean and influence weather all over the world. Together, they are known as the El Nino–Southern Oscillation (ENSO). El Nino is the warm phase, while La Nina is the cool phase. These changes in ocean temperatures and wind patterns can bring extreme weather conditions.

First, under normal conditions, trade winds push warm water from the eastern Pacific to the western Pacific. This movement allows cold, nutrient-rich water to rise in the east, a process called upwelling. During El Nino, these trade winds weaken, so warm water stays in the central and eastern Pacific. This causes changes in rainfall and temperature patterns across many regions.

Next, La Nina is the opposite situation. In this phase, the trade winds strengthen, pushing even more warm water to the west. As a result, the eastern Pacific becomes cooler than usual, and upwelling is stronger. This leads to different global impacts compared to El Nino, such as wetter conditions in Australia and Southeast Asia, and drier weather in the southern United States.

Both El Nino and La Nina have serious effects on ecosystems and human life. For example, El Nino often reduces upwelling, so fish populations decrease along the Pacific coast of South America. On the other hand, La Nina can bring more storms, floods, or even stronger hurricane seasons in some areas. These changes affect agriculture, water supply, and the economy.

Finally, these events usually happen every two to seven years and last for several months. Scientists continue to study ENSO because of its importance for predicting global climate and preparing for natural disasters. Understanding El Nino and La Nina helps countries take action to reduce the risks of droughts, floods, and other extreme weather events.

Sumber:

https://www.climate.gov

https://oceanservice.noaa.gov/facts/ninonina.html

https://psl.noaa.gov/enso/enso_101.html

https://oceantoday.noaa.gov/elninolanina

Class : XI AKL 3

Number : 21

Greenhouse Effect

The greenhouse effect is a natural process that keeps Earth warm enough to support life. It occurs when the Sun’s energy reaches Earth: part of it is absorbed by the land and oceans, while the rest is reflected back into space. The Earth then emits heat in the form of infrared radiation. Certain gases in the atmosphere, such as carbon dioxide (CO₂), methane (CH₄), nitrous oxide (N₂O), and water vapor, trap some of this heat and send it back toward the surface. Thanks to this process, Earth’s average temperature is about 33°C warmer than it would be without the greenhouse effect, making the planet habitable.

However, human activities have increased the concentration of greenhouse gases. Burning fossil fuels for electricity, transportation, and industry, along with deforestation and intensive agriculture, add more CO₂, CH₄, and N₂O to the atmosphere. This enhances the greenhouse effect and leads to global warming.

The impacts are already visible: rising global temperatures, melting glaciers, sea level rise, stronger storms, droughts, floods, and threats to biodiversity. If not addressed, these changes could disrupt food security, health, and economies around the world.

To reduce the enhanced greenhouse effect, people are working on solutions like using renewable energy (solar, wind, hydro), reforestation, energy efficiency, and sustainable farming. On a global scale, countries have joined together through agreements such as the Paris Agreement, aiming to keep global warming below 2°C and ideally under 1.5°C. Protecting the Earth’s climate requires both international cooperation and individual actions, such as reducing waste, saving energy, and planting trees.

link : https://climate.nasa.gov/faq/19/what-is-the-greenhouse-effect/

Class : XI AKL 3

No Absen : 26

First, volcanoes begin to form when intense heat inside the Earth melts rocks and turns them into magma. Then, this magma gathers in a chamber beneath the volcano, and pressure starts to build up. Next, the gases inside the magma expand, which makes the pressure even stronger. When the pressure is too high, the magma pushes through cracks in the Earth’s crust and starts moving upward. Finally, the magma erupts as lava, ash, and gases that explode out of the volcano. This eruption can change the shape of the mountain and damage the environment around it. However, the ash and lava can also create fertile soil that helps plants grow again.

(newest)

1. https://www.britannica.com/story/what-causes-a-volcano-to-erupt

2. https://www.usgs.gov/faqs/how-do-volcanoes-erupt

Class: XI AKL 3

Number:08

A landslide is the downward movement of rock, soil, or debris from a slope under the influence of gravity. Landslides are part of natural geological processes that continuously shape the Earth’s surface, but in many cases they can be accelerated or triggered by human activities and environmental changes. They are considered one of the most common and destructive natural hazards, capable of damaging infrastructure, threatening human lives, and altering landscapes.

Causes of Landslides

Landslides occur when the driving forces acting on a slope exceed the resisting forces that keep soil and rock in place. Several major factors can cause or contribute to this imbalance:

-Heavy or prolonged rainfall: Water infiltrates the ground, increases pore-water pressure, and reduces the strength of soil, making slopes unstable.

-Earthquakes: Seismic activity can shake loose rocks and soil, instantly triggering slope failure.

-Volcanic activity: Explosive eruptions produce loose ash and debris that can mix with water to form dangerous mudflows and debris avalanches.

-Human activities: Deforestation, unregulated mining, construction on steep terrain, and poor land-use planning often remove natural stabilizers such as vegetation, which increases vulnerability to landslides.

-Erosion: Continuous erosion by rivers, glaciers, or ocean waves at the base of a slope gradually weakens its stability.

Types of Landslides

There are various types of landslides, each with distinct characteristics:

1. Translational slide – the downslope movement of soil or rock along a relatively flat surface.

2. Rotational slide (slump) – the movement of material along a curved surface, often leaving behind a concave scar.

3. Rockfall – sudden detachment and free fall of rock fragments from steep cliffs.

4. Debris flow – a rapid flow of water-saturated soil, rock, and organic matter moving down valleys and channels.

5. Soil creep – the slow, long-term downslope movement of soil and rock that gradually tilts trees, poles, and structures.

Impacts of Landslides

The effects of landslides can be devastating. They often destroy houses, roads, bridges, and farmland, leading to economic losses and displacement of communities. In mountainous regions, landslides can block rivers, forming natural dams that may later collapse and cause flash floods. In addition, landslides pose serious risks to human lives, especially in densely populated areas where settlements are built near unstable slopes.

Mitigation and Prevention:

Efforts to reduce landslide risk focus on prevention, monitoring, and preparedness:

-Slope stabilization through engineering techniques such as retaining walls, rock bolts, and terracing.

-Drainage improvement to reduce water infiltration and lower groundwater levels in slopes.

-Reforestation and sustainable land management to restore natural vegetation that strengthens soil.

-Hazard mapping and early warning systems to identify vulnerable zones and alert communities before disasters occur.

-Proper urban planning that avoids construction in high-risk areas.

By combining engineering solutions with environmental conservation and community awareness, the impacts of landslides can be significantly reduced.

Link:

https://www.britannica.com/science/landslide

Class : Xl AKL 3

Absen : 11

In Indonesia, we are very familiar with the word "Tsunami". This natural disaster has ever killed thousands of lives in Banda Aceh a few years ago. Then, how the Tsunami happens?Here is a brief explanation of the process of how the Asian tsunami happens.

Tsunamis can occur if there is a phenomenon which causes the displacement of large amounts of water in the ocean, such as volcanic eruptions, earthquakes, landslides, and meteors that fall to Earth. However, 90% of tsunamis is the result of underwater earthquakes.

Vertical movement in the Earth's crust in the bottom of the ocean causes a sudden up or down movement of sea floor which then causes the water balance disorders above it.

This disturbance causes the occurrence of the flow of the massive sea water energy, that once it reaches the shore, it becomes huge waves resulting Tsunami.

Kelas: XI AKL 3

No. Absen: 09

Global warming refers to the increase in the planet’s overall average temperature in recent decades. Natural processes have always affected Earth’s temperature and climate, but more recently, the planet’s temperature and climate have changed at a higher pace than nature alone can explain. These rapid changes are due to human activities and the widespread use of fossil fuels for energy.

Fossil fuels include coal, oil and natural gas. Burning fossil fuels causes what is known as the “greenhouse effect” in Earth’s atmosphere. The greenhouse effect happens when the sun’s rays penetrate the atmosphere, and the Earth’s surface reflects that heat. Some of the gasses in the atmosphere then trap heat over Earth. Gasses emitted by the burning of fossil fuels are very good at trapping heat and preventing it from leaving the atmosphere. These greenhouse gasses are carbon dioxide, methane, nitrous oxide, chlorofluorocarbons and water vapor.

Countries around the world are trying to lower greenhouse gas emissions to slow global warming. In 2015, nearly 200 countries signed the Paris Agreement at a United Nations Climate Change conference. The international treaty tasks each country with lowering greenhouse gas emissions. The goal is to slow the pace of global warming and prevent Earth’s temperature from rising 2°C (3.6°F) above pre-industrial temperatures.

Source: National Geographic Society https://share.google/CQjFgD28vUjpSFUwR

Class : XI AKL 3

Absent: 14

In September 2025, the sky will be graced by a rare and fascinating phenomenon. A full moon, known as the Corn Moon, will occur simultaneously with a total lunar eclipse , also known as a Blood Moon.

The full moon that falls in September has a special name. The term "Corn Moon" is used to describe the full moon that occurs during the corn harvest season in the Northern Hemisphere. This phenomenon is an important landmark for farmers and has been part of a long-standing tradition.

What Is a Corn Moon and Why Is It Called That?

The Corn Moon is the name for the full moon that occurs in September. According to The Old Farmer's Almanac, this name stems from Native American and European traditions that associated the full moon with agricultural activity. The Corn Moon marks the ideal time to harvest crops, especially corn, which ripens in the fall.

Other names for full moons derived from agricultural and natural traditions include the Strawberry Moon (June) or the Harvest Moon (September/October). Astronomically, the Corn Moon is still a regular full moon, but these names carry unique cultural and historical significance

When Will the Corn Moon 2025 Occur?

According to the Time and Date website , the Corn Moon will peak on Sunday, September 7, 2025. This moment occurs when the Moon is opposite the Sun, so the entire surface of the Moon facing Earth will appear perfectly lit. The peak time will vary depending on the time zone in each region.

In Indonesia, the Corn Moon will peak at night, creating a beautiful sight for the public. This phenomenon is special because it coincides with a total lunar eclipse, which peaks at midnight into the early morning hours of Monday, September 8, 2025.

The Appearance of the Corn Moon Coincides with the Total Lunar Eclipse

The Corn Moon on September 7, 2025, will be even more special because it will appear simultaneously with a total lunar eclipse. As reported by EarthSky , during a total lunar eclipse, the Moon will enter Earth's dark shadow and turn reddish. This event is often referred to as a Blood Moon.

https://news.detik.com/berita/d-8097985/fenomena-corn-moon-2025-muncul-bersamaan-gerhana-bulan-total

How Riverbank Erosion Occurs

Riverbank erosion is the natural process through which material is worn away from the banks (and sometimes beds) of rivers and streams. This occurs when the energy of flowing water exceeds the resistance offered by the bank material or soil structure.

According to UNDRR, riverbank erosion takes place via three main mechanisms:

1. Fluvial Scour – Occurs when hydraulic forces from flowing water exceed the soil’s ability to resist, causing sediments at the bank or bed to be carried away.

2. Mass Failure – Happens when large portions of the bank collapse or slump, usually after becoming over-steepened or undermined by fluvial scour.

3. Subaerial Erosion – Involves erosion from processes outside direct water flow, such as groundwater seepage, animal trampling (like cattle tracks), wet–dry cycles, frost action, or human disturbances.

Riverbank erosion is influenced by the balance between driving forces and resisting forces:

-Driving forces include hydraulic energy (e.g., faster flows or flooding), which intensify fluvial scour.

-Resisting forces encompass soil cohesion, vegetation that stabilizes banks, and groundwater conditions. Vegetation plays a critical role by reinforcing soil and reducing flow velocities near the bank.

When driving forces increase (like during floods) or resisting forces weaken (e.g., due to vegetation removal), erosion accelerates.

Several **natural and human-induced factors** can amplify riverbank erosion:

-Flood events dramatically raise hydraulic energy and can lead to sudden erosion or bank collapse.

-Vegetation loss (e.g., deforestation or grazing) reduces root reinforcement and exposes soil to direct erosion.

-Human activities such as sand mining, dam constructions, river channel modifications, and embankment failures disrupt natural flow and stability.

-In cold climates, processes like freeze–thaw cycles and movement of river ice also contribute to erosion.

Erosion is not an isolated event—it is part of a continuous cycle of erosion and accretion, where eroded materials are transported and deposited elsewhere, forming new landforms such as bars and deltas.

Loss of land — Significant land loss, especially in floodplains, can threaten agriculture, infrastructure, and habitations (e.g., it’s estimated that in parts of South Asia, rivers cause thousands of hectares of land erosion annually).

Sediment transport — Increased sediment loads degrade water quality, affecting both human uses and aquatic ecosystems.

Riverbank erosion is a natural geomorphic process driven by water energy overpowering soil resistance. It progresses through mechanisms like fluvial scour, mass failure, and subaerial erosion, and is further accelerated by floods, vegetation loss, and human intervention. While ongoing and natural, erosion can pose hazards when intensified. Understanding these processes is essential for effective riverbank management and land-use planning.

Source: https://www.undrr.org/understanding-disaster-risk/terminology/hips/gh0404

class : Xl AKL 3

Absen : 22

A solar eclipse is one of the most fascinating natural phenomena that humans can witness. It occurs when the Moon passes directly between the Earth and the Sun, casting its shadow onto our planet. For a brief moment, the Sun’s light is either partially or completely blocked, creating a dramatic and awe-inspiring view from the Earth.

The process only happens when the Sun, the Moon, and the Earth are perfectly aligned. Depending on where the shadow falls, people on Earth may experience different types of solar eclipses. If the Moon completely covers the Sun, observers see a total eclipse, revealing the Sun’s faint outer atmosphere known as the corona. When the Moon is slightly farther away, it appears smaller and cannot fully cover the Sun, creating a glowing ring of fire called an annular eclipse. In other areas, people may only see a partial eclipse, where the Moon blocks just part of the Sun. Very rarely, a hybrid eclipse occurs, appearing as total in some regions and annular in others.

Although the Moon orbits the Earth every month, solar eclipses do not happen as often as one might think. This is because the Moon’s orbit is tilted about 5 degrees relative to Earth’s orbit around the Sun. Only when the Moon crosses the same plane as Earth’s orbit during a new moon can an eclipse take place.

Solar eclipses have always captured human imagination, sometimes even inspiring myths and legends. Yet beyond their beauty, they also remind us of the precise mechanics of the universe. Interestingly, from our perspective on Earth, the Sun and the Moon look almost the same size—despite the Sun being 400 times larger but also about 400 times farther away.

Because of this cosmic coincidence, we are able to witness solar eclipses. However, they are rare events in any single location—sometimes occurring only once every few centuries. And in the distant future, as the Moon slowly drifts farther from Earth, total solar eclipses will eventually disappear.

While solar eclipses are beautiful, they must be observed safely. Looking directly at the Sun without proper protection can cause serious eye damage. That’s why scientists recommend using special solar eclipse glasses or indirect viewing methods.

In the end, a solar eclipse is not just a celestial event—it is a reminder of how vast, dynamic, and extraordinary our universe truly is.

sumber :

1. https://id.m.wikipedian.com

2. https://www.detik.com

3. https://www.halodoc.com

4. https://bossch.itb.ac.id

Class : XI AKL 1

No : 02

A landslide is a natural disaster that occurs when a mass of soil, rocks, or debris moves down a slope. It usually happens suddenly and can cause serious damage to the environment, property, and even human lives.

Landslides happen because of several factors. The main factor is heavy rainfall. When rainwater soaks into the ground, it makes the soil loose and heavy. If the soil cannot hold together anymore, it will slide down.

Another factor is deforestation. When trees are cut down, their roots can no longer hold the soil. This makes the land unstable and more easily moved by water or gravity. Earthquakes can also trigger landslides by shaking the ground and breaking the soil structure.

Human activities, such as mining or building houses on steep slopes, increase the risk of landslides. These activities disturb the natural balance of the land and make it weak.

In short, landslides are caused by natural factors like rain and earthquakes, as well as human activities such as deforestation and construction on steep areas. Preventing landslides requires maintaining forests, making proper drainage, and avoiding building on risky slopes.

Class :XI AKL 3

Number :30

A meteor shower is an astronomical phenomenon that occurs when a number of meteors appear to shine in the night sky. These meteors are caused by fragments of celestial bodies called meteoroids entering Earth's atmosphere at high speed.

Celestial objects of sufficient size have the potential to become shooting stars. Sometimes Earth passes through dust clouds or encounters asteroid fragments, close enough to be attracted by Earth's gravity. Or sometimes, asteroid fragments happen to orbit Earth.

The National Institute of Aeronautics and Space (LAPAN) explains that meteor showers occur when Earth encounters a passing celestial body and the rocky dust it carries into Earth's atmosphere. This encounter causes friction between Earth's atmosphere and the meteoroids coming from outside Earth's atmosphere. These celestial bodies encounter Earth because they also orbit the Sun. These celestial bodies burn up at a temperature of 1,650 degrees Celsius upon entering the atmosphere. This combustion process is what the human eye sees as falling meteors.

SUMBER:

https://share.google/images/NMDoTRX4884KExniu

Class: XI AKL 1

Number: 12

Flood is one of the most common natural disasters in the world. It happens when a large amount of water covers areas of land that are usually dry.

Floods usually occur because of heavy rainfall. When rain falls continuously, the soil cannot absorb all the water. As a result, rivers and drainage systems overflow.

Besides natural factors, human activities also play an important role. Deforestation reduces the ability of the land to absorb water. Throwing garbage into rivers blocks the water flow, and building houses in low areas makes it easier for water to accumulate. Poor drainage systems in cities also increase the risk of floods.

Climate change is another factor that makes floods worse. Unpredictable weather and extreme rainfall cause higher chances of flooding in many regions.

Therefore, floods happen because of both natural factors and human activities. Protecting the environment and managing water properly are important steps to reduce the risk of floods.

Class : XI AKL 3

No Absent : 19

The ocean appears blue primarily because water absorbs light of longer wavelengths (reds, oranges, yellows) more strongly than it absorbs blue light . When sunlight penetrates water, the redder colors fade quickly with depth, while blue wavelengths remain, giving water bodies their blue appearance .

In open ocean areas where the water is very clear, the blue hue is most pronounced. Particles like sediments or algae can shift the color toward green or brown by altering the absorption or scattering of different wavelengths .

Although it's a common belief that oceans simply reflect the blue sky, both the sky and the sea appear blue independently—both due to how light interacts with molecules, not reflection.

Link :

https://www.scientificamerican.com/article/why-does-the-ocean-appear/?utm_source=chatgpt.com

How Riverbank Erosion Occurs

Riverbank erosion is the natural process of soil and sediment being worn away from the sides of rivers and streams. It happens when the energy of moving water is stronger than the resistance of the soil and bank materials. This process shapes river channels and influences surrounding landscapes over time. Although it is natural, riverbank erosion can cause significant changes in both human and natural environments. Understanding the causes and processes is important for managing rivers and reducing damage. This explanation is based on information from the United Nations Office for Disaster Risk Reduction (UNDRR).

Riverbank erosion occurs through three main mechanisms. The first is fluvial scour, where flowing water exerts hydraulic forces that remove soil particles from the riverbank. The second is mass failure, which takes place when sections of the riverbank collapse due to being undercut or over-steepened. The third is subaerial erosion, caused by processes like groundwater seepage, frost action, animal trampling, or human activity. Each mechanism weakens the riverbank in different ways, but all contribute to gradual or sudden erosion. Together, they explain how rivers continuously reshape their channels.

The process of erosion depends on the balance between driving forces and resisting forces. Driving forces include water energy from flow and floods, which increase pressure on riverbanks. Resisting forces come from soil strength, plant roots that stabilize soil, and natural bank structures. Vegetation is especially important because it reinforces the soil and reduces water velocity at the riverbank. When driving forces become stronger than resisting forces, erosion happens more quickly. This balance is sensitive to both natural conditions and human activities.

Several conditions can amplify riverbank erosion. Floods increase water speed and energy, often leading to rapid erosion or sudden collapse of the banks. Vegetation loss, such as from deforestation or overgrazing, reduces the natural strength of the soil. Human activities like sand mining, dam construction, and river channel modifications also weaken riverbanks. In colder regions, freeze–thaw cycles and the movement of ice can further accelerate erosion. These factors show that both nature and humans play a role in intensifying the process.

Riverbank erosion is not a one-time event but part of a continuous cycle. As soil and sediments are eroded from one place, they are transported and deposited elsewhere. This creates new landforms, such as bars, islands, or deltas in different parts of the river. The cycle of erosion and accretion means rivers are always changing shape. While this process is natural, its effects can be harmful if erosion happens too quickly. Communities near rivers often experience both land loss and new land formation at the same time.

The impacts of riverbank erosion can be serious for both people and ecosystems. One major effect is the loss of land, which threatens agriculture, infrastructure, and housing near rivers. Increased sediment in rivers also lowers water quality and affects aquatic life. Turbidity and high sediment loads can damage fish habitats and reduce biodiversity. For humans, erosion may cause displacement and economic losses in farming communities. These impacts show why riverbank erosion, although natural, can become a hazard when accelerated.

Riverbank erosion is a continuous process that occurs when water energy overcomes the resistance of soil and vegetation. It works through mechanisms such as fluvial scour, mass failure, and subaerial erosion. The process is influenced by floods, vegetation cover, soil strength, and human activities. While erosion and accretion are natural cycles that shape rivers, they can also cause environmental damage and social problems. Effective river management is necessary to balance natural changes with human safety. By understanding erosion, societies can better prepare for and reduce its risks.

source: https://www.undrr.org/understanding-disaster-risk/terminology/hips/gh0404

Class : XI AKL 3

Number : 2

The rain of fish phenomenon, or Lluvia de Peces, is a rare natural event that occurs in Yoro, Honduras. It usually happens once a year, particularly after heavy storms in May or June. When the rain subsides, residents often find live fish scattered on streets, fields, and even in their yards.

This phenomenon has been known since the 19th century. According to local legend, it first occurred in the 1850s when a Catholic priest named Father Jose Manuel prayed for starving villagers. Shortly after his prayers, a violent storm struck the area, and fish began falling from the sky. Since then, the people of Yoro have considered the event a miracle.

From a scientific perspective, several theories attempt to explain how this phenomenon occurs. One explanation points to the formation of waterspouts, or tornadoes over water. These whirlwinds can suck up water along with small fish and carry them into the atmosphere. Once the storm reaches land, the fish are released and fall together with the rain.

Another explanation suggests that heavy rainfall causes flooding in the Yoro region. The overflowing water may carry fish from rivers or underground streams. When the floodwaters recede, the fish remain on the ground, giving the impression that they fell from the sky.

In the 1970s, a team from National Geographic also investigated the phenomenon. They proposed that the fish might come from underground aquifers, pushed to the surface by strong rainfall. However, no research has been able to fully confirm this theory.

Until today, the rain of fish in Yoro remains a mystery. Although several scientific theories have been proposed, none can fully explain it. For the local community, this phenomenon is not just a natural event but also a blessing to be grateful for. Since 1998, the people of Yoro have held an annual parade to celebrate the rain of fish while honoring Father Jose Manuel, whom they believe brought the first miracle of fish rain to their land.

link sumber : https://share.google/I81GF2Ks26AAhsqYD

Kelas : XI AKL 3

Absen : 24

Acid rain is rainfall that has a higher level of acidity than normal rain. This phenomenon usually occurs due to air pollution caused by human activities as well as natural factors, which then bring harmful impacts to the environment.

The process of acid rain begins with the release of sulfur dioxide (SO₂) and nitrogen oxides (NOx). These gases are produced from burning fossil fuels, vehicle emissions, industrial activities, and volcanic eruptions. When they rise into the atmosphere, the gases react with water vapor and oxygen to form sulfuric acid (H₂SO₄) and nitric acid (HNO₃), which later mix with rainwater and fall to the Earth’s surface.

The impacts of acid rain are very dangerous, such as damaging soil fertility, harming plant growth, polluting water ecosystems, and accelerating the corrosion of buildings and metals. Therefore, preventive efforts are needed, such as reducing fossil fuel use, switching to renewable energy, and preserving nature through reforestation to minimize the risk of acid rain.

Kelas : XI AKL 3

Absen : 24

The natural phenomenon of acid rain can occur due to air pollution containing nitric and sulfuric acids. Its pH, or acidity level, is less than 5.7. The normal pH of water is 7. Acid rain is triggered by increased emissions of sulfur dioxide (SO2) and nitrogen oxides (NOx) in the atmosphere.

Although considered dangerous, acid rain appears no different from regular rain. It has no distinctive characteristics. Its color and taste are the same. However, acid rain can also fall in the form of snow. Upon closer examination, its pH is indeed low, unlike regular water, which has a normal pH of 7. If this acid rain continues to occur, it will certainly be dangerous to health, as it indicates high levels of pollution.

To prevent acid rain, humans must limit the use of fossil fuels, such as oil and coal, and begin to shift to other sustainable energy sources, such as solar or wind power.

link sumber:

https://temanggung.pikiran-rakyat.com/pendidikan/pr-2615810564/teks-eksplanasi-singkat-tentang-hujan-asam-disusun-sesuai-strukturnya

No/class : 24/XI AKL 1

The Andromeda Galaxy is the closest spiral galaxy to the Milky Way, approximately 2.52 million light-years from Earth. It is one of the few galaxies visible to the naked eye on a clear, moonless night without light pollution. It takes its name from the constellation in which it appears, Andromeda, named after a princess married to Perseus in Greek mythology.Historically, it was known as a "faint cloud" in Western astronomy before the concept of a galaxy was established. It is cataloged as Messier 31 and NGC 224.

The formation of Andromeda is believed to have started around 10 billion years ago from clouds of gas and dust that were pulled together by gravity. Like the Milky Way, Andromeda also has a supermassive black hole at its center that helps maintain the stability of the surrounding stars.

Impressively, the Andromeda Galaxy is

moving toward the Milky Way at a speed of about 110 km per second. Scientists estimate that in the next 4–5 billion years, these two galaxies will collide and eventually merge into a much larger galaxy, often called “Milkomeda.”

With its enormous size and important role in the evolution of the universe, the Andromeda Galaxy remains one of the most fascinating objects for scientists to study.

LINK :https://id.wikipedia.org/wiki/Galaksi_Andromeda

🔗 https://www.vectorsolutions.com/resources/blogs/papermaking-process/

Name : Rizki Rahmattulloh

Class : XI AKL 1

No : 29

Overthinking is basically the habit of thinking too much about something, usually the negative stuff. It often goes in circles without giving any real solution, and in the end it can cause stress, anxiety, or even depression.

It usually shows up in three ways: the past, the present, and the future. In the past, people often regret decisions they made or keep replaying embarrassing moments. In the present, it shows up as questioning relationships, work, or whatever’s going on right now. And when it comes to the future, it usually looks like worrying about things that haven’t even happened yet, like career failure or not being happy in life.

Some common signs of overthinking are: not being able to stop thinking about something, constantly doubting decisions, imagining the worst-case scenario, feeling anxious, struggling to focus, and even having trouble sleeping. The effects are also pretty heavy—mentally it can increase stress and anxiety, physically it can cause fatigue and insomnia, and socially it can make it harder to enjoy time with others. Productivity also tends to drop because it’s tough to stay focused.

The good news is, overthinking can be managed. You can try limiting the time you spend on a problem, figuring out the root cause, focusing on solutions, challenging negative thoughts with more realistic ones, or practicing relaxation techniques like meditation or yoga. These steps can help you stay calmer and avoid getting stuck in that endless cycle of thoughts.

So yeah, overthinking is something almost everyone goes through, but if you let it go unchecked, it can mess things up. Learning to manage your thoughts and practicing simple strategies can really help you live a calmer, healthier, and happier life.

Link :

https://www.idionline.org/article/mengenal-overthinking-memahami-dampak-dan-cara-mengatasinya

Class : XI AKL 1

No Absen : 10

On August 28, 2025, massive demonstrations broke out across several regions of Indonesia, particularly in Jakarta. The protest was led by labor unions under KSPI, the Labor Party, and the Workers’ Union Coalition, carrying the slogan HOSTUM (Abolish Outsourcing, Reject Cheap Wages). Thousands of workers—around 10,000 people from Jabodetabek and 37 other provinces—gathered in front of the Indonesian House of Representatives (DPR RI) from morning until midday.

Initially, the protest proceeded peacefully, with speeches delivered by labor leaders such as Said Iqbal. A total of 4,531 TNI-Polri personnel were deployed to secure the demonstration. By around 1:00 PM, the workers began dispersing, although several protest banners remained attached to the DPR’s fence.

After the workers left, the demonstration continued with student groups. The situation then escalated into chaos: protesters threw bottles, ignited firecrackers, burned tires, blocked road access, and even attempted to climb the DPR fence. Security forces responded with water cannons and tear gas. Police stated that the riots intensified due to the presence of unidentified provocateurs who incited anarchic actions.

The unrest led to a tragic incident. An online motorcycle taxi driver, Affan Kurniawan, was killed after being run over by a Brimob Barracuda vehicle in the Bendungan Hilir area. This incident sparked public outrage and became a major focal point. Police announced that the case was under investigation by the Professional and Security Division (Propam) and the National Police Headquarters, with seven Brimob members under questioning.

In addition to the fatality, hundreds of injuries were recorded, affecting both demonstrators and security personnel. The Jakarta Provincial Government confirmed that it would cover the medical expenses of the injured victims.

Class: XI AKL 1

Absent number: 11

late afternoon

Twilight is the transition between day and night, when the sun begins to sink toward the horizon. The sky slowly loses its blue and transforms into a gradient of colors—fiery red, golden orange, soft purple, and finally deep blue that welcomes the night. The sunlight, once harsh, turns warm and gentle, casting golden tones on trees, buildings, and people’s faces. Shadows stretch longer, birds return to their nests, and the atmosphere feels quieter.

For many, twilight is seen as a symbol of calm, the closing of the day, or even a moment of self-reflection. Some find it romantic, while others feel a hint of melancholy, as if twilight carries the message that everything beautiful will eventually come to an end—yet it will always return again the next day.

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