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(Image credit: NASA's Goddard Space Flight Center/S. Wiessinger)

Red dwarf stars make up the largest population of stars in the galaxy, but they hide in the shadows, too dim to be seen with the naked eye from Earth. Their limited radiance helps to extend their lifetimes, which are far greater than that of the sun.

Scientists think that 20 out of the 30 stars near Earth are red dwarfs. The closest star to the sun, Proxima Centauri, is a red dwarf.

The term "red dwarf" does not refer to a single kind of star. It is frequently applied to the coolest objects, including K and M dwarfs - which are true stars - and brown dwarfs, often referred to as "failed stars" because they do not sustain hydrogen fusion in their cores.

"There is no true definition of red dwarfs," astronomer Michaël Gillon of the University of Liège in Belgium told Space.com by email. Gillon, who studies stellar objects at the cooler end of the spectrum, was part of the team that identified the ultracool star TRAPPIST-1. Red dwarf "generally refers to dwarf stars with a spectral type ranging from K5V to M5V," Gillon said.

Formation and characteristics

Red dwarfs form like other main-sequence stars. First, a cloud of dust and gas is drawn together by gravity and begins rotating. The material then clumps at the center, and when it reaches the critical temperature, fusion begins.

Red dwarfs include the smallest of the stars, weighing between 7.5% and 50% the mass of the sun. Their reduced size means that they burn at a lower temperature, reaching only 6,380 degrees Fahrenheit (3,500 degrees Celsius). The sun, by comparison, has a temperature of 9,900 F (5,500 C). The low temperatures of red dwarfs mean they are far, far dimmer than stars like the sun.

Their low temperature also means that they burn through their supply of hydrogen less rapidly. While other, more massive stars burn through only the hydrogen at their core before coming to the end of their lifetimes, red dwarfs consume all of their hydrogen, inside and outside their core. This stretches out the lifetime of red dwarfs to trillions of years; far beyond the 10-billion-year lifetime of sun-like stars.

(Image credit: NASA/JPL-Caltech)

Classifying red dwarfs

Scientists occasionally have difficulty distinguishing a red dwarf star from a brown dwarf. Brown dwarfs are cool and dim, and likely form the same way red dwarfs do, but brown dwarfs never reach the point of fusion because they're too small, and therefore, they're not considered stars.

"When we observe a red dwarf and measure its atmosphere, we don't necessarily know whether it's a brown dwarf or a star - young brown dwarfs look almost exactly like ultracool stars," said Adam Burgasser, an astronomer at the University of California, San Diego.

To figure out whether a celestial object is a brown or red dwarf, scientists measure the temperature of the object's atmosphere. Fusion-free brown dwarfs are cooler than 2,000 Kelvin (3,140 F or 1,727 C), while hydrogen-fusing stars are warmer than 2,700 K (4,400 F or 2,427 C). In between, a star could be classified as a red dwarf or brown dwarf.

Sometimes, chemicals in the object's atmosphere can reveal clues about what's happening at its heart. According to Burgasser, the presence of molecules like methane or ammonia, which can only survive at cold temperatures, suggests that an object is a brown dwarf. Lithium in the atmosphere also suggests that a red dwarf is a brown dwarf rather than a true star.

But scientists may still use the term red dwarf to describe how a celestial object looks - small and dim - even if the object is actually a brown dwarf, Burgasser said.

(Image credit: NASA/JPL-Caltech)

A host of habitable planets?

Planets form from the material left over in a disk after their star has been created. Many red dwarfs have been found with planets surrounding them, though enormous gas giants are rare. Because red dwarfs are dimmer than stars like the sun, it is easier to find small planets that may surround these dimmer objects, making red dwarfs a popular target for planet hunting. NASA's Kepler space telescope (which operated between 2009 and 2018) and Transiting Exoplanet Survey Satellite, or TESS (which started operations in 2018), have surveyed many red dwarf stars for possible Earth-like planets.

Since the planets examined by TESS are near bright stars that tend to be close to Earth, it's easier for ground telescopes to follow up on the observations. In April 2019, TESS investigators announced they had found their mission's first Earth-size planet, although its conditions are not ideal for life as we know it.

For a long time, scientists thought red dwarfs were uninhabitable. Their limited light and heat meant that the habitable zone - or the region where liquid water could form on planets around a red dwarf - would be very close to the star, putting the planets in range of harmful radiation from the star. Other planets may be tidally locked to the star, with one side constantly facing the sun, causing one side to be too warm, and the other to be too cold.

In 2016, a potentially habitable planet was found orbiting Proxima Centauri (Earth's closest star). And in 2019, astronomers announced the possibility of a second planet orbiting far outside the star's habitable zone. At least seven Earth-size planets orbit the red dwarf , and many studies suggest at least some of those planets could host life.

(Image credit: David A. Aguilar (CfA))

The end of the line

Tiny red dwarfs may have an extended lifetime, but like all other stars, they'll eventually burn through their supply of fuel. When they do, the red dwarfs become white dwarfs - dead stars that no longer undergo fusion at their core. Eventually, the white dwarfs will radiate away all of their heat and become black dwarfs.

But unlike the sun, which will become a white dwarf in a few billion years, red dwarfs will take trillions of years to burn through their fuel. This is significantly longer than the age of the universe, which is less than 14 billion years old. Red dwarfs may be a bit dim, but like the tortoise, they slowly but surely win the survival race.
Additional resources: This article was updated on June 6, 2019 by Space.com contributor Elizabeth Howell.

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Red Dwarfs: The Most Common and Longest-Lived Stars

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Most of the star nearest to Earth are red dwarfs, but they are too dim to be seen with the naked eye.

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This type of star has a very simple lifecycle since all that happens is that first it is formed like any other star but a lot smaller and because of that its fuel burns of a lot slower which means that it has a very long lifecycle. Even though they can't be seen by the naked eye because of it's weak brightness, these types of stars are the most common so they make up most of the stars close to Earth.

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What are stars made of?

Stars form from nebulas in the galaxy, as soon as the star is born some things can be concluded, depending on the size of the star it has different future fates.

Main sequence stars such as our Sun after a lot of nuclear fusion will become a red giant, then later slowly its outer layers will expand until all that's left is a white dwarf.

However, if the star is bigger than the first it will also become a red hypergiant. Still, two different things can happen: it will either end its life with a supernova explosion and leave behind only its core (neutron star) or become a black hole.

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Astronomers Once Watched a Star Turn Directly Into a Black Hole

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Stars that aren't so big to end in a supernova have a different story they slowly lose their mass but eventually, all that's left is its core and that is what we call white dwarfs. These objects have a very high temperature and are some of the hottest objects known and because there is nowhere for this heat to go white dwarfs will last for a very long time in a sort of stable state. Eventually, they will lose all their brightness and become a black dwarf.

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The life cycle of a neutron star - David Lunney

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Astronomers estimate that the universe could contain up to one septillion stars – that’s a one followed by 24 zeros. Our Milky Way alone contains more than 100 billion, including our most well-studied star, the Sun. Stars are giant balls of hot gas – mostly hydrogen, with some helium and small amounts of other elements. […]

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(Image credit: solarseven via Getty Images)

Black holes are some of the strangest and most fascinating objects in space. They're extremely dense, with such strong gravitational attraction that not even light can escape their grasp.

The Milky Way could contain over 100 million black holes, though detecting these gluttonous beasts is very difficult. At the heart of the Milky Way lies a supermassive black hole - Sagittarius A*. The colossal structure is about 4 million times the mass of the sun and lies approximately 26,000 light-years away from , according to a statement from NASA.

The first image of a black hole was captured in 2019 by the Event Horizon Telescope (EHT) collaboration. The striking photo of the black hole at the center of the M87 galaxy 55 million light-years from Earth thrilled scientists around the world.

Related: White holes: What we know about black holes' neglected twins

Black hole FAQs answered by an expert

We asked theoretical astrophysicist Priyamvada Natarajan a few commonly asked questions about black holes.

Theoretical Astrophysicist

First black hole discovered

Albert Einstein first predicted the existence of black holes in 1916, with his general theory of relativity. The term "black hole" was coined many years later in 1967 by American astronomer John Wheeler. After decades of black holes being known only as theoretical objects.

The first black hole ever discovered was Cygnus X-1, located within the Milky Way in the constellation of Cygnus, the Swan. Astronomers saw the first signs of the black hole in 1964 when a sounding rocket detected celestial sources of X-rays according to NASA. In 1971, astronomers determined that the X-rays were coming from a bright blue star orbiting a strange dark object. It was suggested that the detected X-rays were a result of stellar material being stripped away from the bright star and "gobbled" up by the dark object - an all-consuming black hole.

How many black holes are there?

According to the Space Telescope Science Institute (STScI) approximately one out of every thousand stars is massive enough to become a black hole. Since the Milky Way contains over 100 billion stats, our home galaxy must harbor some 100 million black holes.

Though detecting black holes is a difficult task and estimates from NASA suggest there could be as many as 10 million to a billion stellar black holes in the Milky Way.

The closest black hole to Earth is dubbed " The Unicorn" and is situated approximately 1,500 light-years away. The nickname has a double meaning. Not only does the black hole candidate reside in the constellation Monoceros ("the unicorn"), its incredibly low mass - about three times that of the sun - makes it nearly one of a kind.
Related: How many black holes are there in the universe?
Black hole images

In 2019 the Event Horizon Telescope (EHT) collaboration released the first image ever recorded of a black hole. The EHT saw the black hole in the center of galaxy M87 while the telescope was examining the event horizon or the area past which nothing can escape from a black hole. The image maps the sudden loss of photons (particles of light). It also opens up a whole new area of research in black holes, now that astronomers know what a black hole looks like.

In 2021, astronomers revealed a new view of the giant black hole at the center of M87, showing what the colossal structure looks like in polarized light. As polarized light waves have a different orientation and brightness compared to unpolarized light, the new image shows the black hole in even more detail. Polarization is a signature of magnetic fields and the image makes it clear that the black hole's ring is magnetized.

In May 2022, scientists revealed the historic first image of the supermassive black hole at the center of our galaxy - Sagitarrius A*.

Related: The 1st photo of the Milky Way's monster black hole explained in images

What do black holes look like?

Black holes have three "layers": the outer and inner event horizon, and the singularity.

The event horizon of a black hole is the boundary around the mouth of the black hole, past which light cannot escape. Once a particle crosses the event horizon, it cannot leave. Gravity is constant across the event horizon.

The inner region of a black hole, where the object's mass lies, is known as its singularity, the single point in space-time where the mass of the black hole is concentrated.

Scientists can't see black holes the way they can see stars and other objects in space. Instead, astronomers must rely on detecting the radiation black holes emit as dust and gas are drawn into the dense creatures. But supermassive black holes, lying in the center of a galaxy, may become shrouded by the thick dust and gas around them, which can block the telltale emissions.

Sometimes, as matter is drawn toward a black hole, it ricochets off the event horizon and is hurled outward, rather than being tugged into the maw. Bright jets of material traveling at near-relativistic speeds are created. Although the black hole remains unseen, these powerful jets can be viewed from great distances.

The EHT's image of a black hole in M87 (released in 2019) was an extraordinary effort, requiring two years of research even after the images were taken. That's because the collaboration of telescopes, which stretches across many observatories worldwide, produces an astounding amount of data that is too large to transfer via the internet.

With time, researchers expect to image other black holes and build up a repository of what the objects look like. The next target is likely Sagittarius A*, which is the black hole in the center of our own Milky Way galaxy. Sagittarius A* is intriguing because it is quieter than expected, which may be due to magnetic fields smothering its activity, a 2019 study reported. Another study that year showed that a cool gas halo surrounds Sagittarius A*, which gives unprecedented insight into what the environment around a black hole looks like.

Types of black holes

So far, astronomers have identified three types of black holes: stellar black holes, supermassive black holes and intermediate black holes.

Stellar black holes - small but deadly

When a star burns through the last of its fuel, the object may collapse, or fall into itself. For smaller stars (those up to about three times 's mass), the new core will become a neutron star or a white dwarf. But when a larger star collapses, it continues to compress and creates a stellar black hole.

Black holes formed by the collapse of individual stars are relatively small but incredibly dense. One of these objects packs more than three times the mass of the sun into the diameter of a city. This leads to a crazy amount of gravitational force pulling on objects around the object. Stellar black holes then consume the dust and gas from their surrounding galaxies, which keeps them growing in size.

Supermassive black holes - the birth of giants

Small black holes populate the universe, but their cousins, supermassive black holes, dominate. These enormous black holes are millions or even billions of times as massive as the sun but are about the same size in diameter. Such black holes are thought to lie at the center of pretty much every galaxy, including the Milky Way.

Scientists aren't certain how such large black holes spawn. Once these giants have formed, they gather mass from the dust and gas around them, material that is plentiful in the center of galaxies, allowing them to grow to even more enormous sizes.

Supermassive black holes may be the result of hundreds or thousands of tiny black holes that merge. Large gas clouds could also be responsible, collapsing together and rapidly accreting mass. A third option is the collapse of a stellar cluster, a group of stars all falling together. Fourth, supermassive black holes could arise from large clusters of dark matter. This is a substance that we can observe through its gravitational effect on other objects; however, we don't know what dark matter is composed of because it does not emit light and cannot be directly observed.

Scientists once thought that black holes came in only small and large sizes, but research has revealed the possibility that midsize, or intermediate, black holes (IMBHs) could exist. Such bodies could form when stars in a cluster collide in a chain reaction. Several of these IMBHs forming in the same region could then eventually fall together in the center of a galaxy and create a supermassive black hole.

In 2014, astronomers found what appeared to be an intermediate-mass black hole in the arm of a spiral galaxy. And in 2021 astronomers took advantage of an ancient gamma-ray burst to detect one.

"Astronomers have been looking very hard for these medium-sized black holes," study co-author Tim Roberts, of the University of Durham in the United Kingdom, said in a statement. "There have been hints that they exist, but IMBHs have been acting like a long-lost relative that isn't interested in being found."

Research, from 2018, suggested that these IMBHs may exist in the heart of dwarf galaxies (or very small galaxies). Observations of 10 such galaxies (five of which were previously unknown to science before this latest survey) revealed X-ray activity - common in black holes - suggesting the presence of black holes of from 36,000 to 316,000 solar masses. The information came from the Sloan Digital Sky Survey, which examines about 1 million galaxies and can detect the kind of light often observed coming from black holes that are picking up nearby debris.

Binary black holes: double trouble

In 2015, astronomers using the Laser Interferometer Gravitational-Wave Observatory (LIGO) detected gravitational waves from merging stellar black holes.

"We have further confirmation of the existence of stellar-mass black holes that are larger than 20 solar masses - these are objects we didn't know existed before LIGO detected them," David Shoemaker, the spokesperson for the LIGO Scientific Collaboration (LSC), said in a statement. LIGO's observations also provide insights into the direction a black hole spins. As two black holes spiral around one another, they can spin in the same direction or the opposite direction.

There are two theories on how binary black holes form. The first suggests that the two black holes in a binary form at about the same time, from two stars that were born together and died explosively at about the same time. The companion stars would have had the same spin orientation as one another, so the two black holes left behind would as well.

Under the second model, black holes in a stellar cluster sink to the center of the cluster and pair up. These companions would have random spin orientations compared to one another according to LIGO Scientific Collaboration. LIGO's observations of companion black holes with different spin orientations provide stronger evidence for this formation theory.

"We're starting to gather real statistics on binary black hole systems," said LIGO scientist Keita Kawabe of Caltech, who is based at the LIGO Hanford Observatory. "That's interesting because some models of black hole binary formation are somewhat favored over the others even now, and in the future, we can further narrow this down."

If you fell into a black hole, theory has long suggested that gravity would stretch you out like spaghetti, though your death would come before you reached the singularity. But a 2012 study published in the journal Nature suggested that quantum effects would cause the event horizon to act much like a wall of fire, which would instantly burn you to death.

Black holes don't suck. Suction is caused by pulling something into a vacuum, which the massive black hole definitely is not. Instead, objects fall into them just as they fall toward anything that exerts gravity, like the Earth.

The first object considered to be a black hole is Cygnus X-1. Cygnus X-1 was the subject of a 1974 friendly wager between Stephen Hawking and fellow physicist Kip Thorne, with Hawking betting that the source was not a black hole. In 1990, Hawking conceded defeat.

Miniature black holes may have formed immediately after the Big Bang. Rapidly expanding space may have squeezed some regions into tiny, dense black holes less massive than the sun.

If a star passes too close to a black hole, the star can be torn apart.

Astronomers estimate that the Milky Way has anywhere from 10 million to 1 billion stellar black holes, with masses roughly three times that of the sun.

Black holes remain terrific fodder for science fiction books and movies. Check out the movie "Interstellar," which relied heavily on Thorne to incorporate science. Thorne's work with the movie's special effects team led to scientists' improved understanding of how distant stars might appear when seen near a fast-spinning black hole.

Black hole facts

Additional resources

Dive deeper into the mystery of black holes with NASA Science. Watch videos and read more about black holes from NASA's Hubblesite. Discover more about black holes with the National Science Foundation.

Bibliography

Hubblesite: Black holes: Gravity's relentless pull interactive: Encyclopedia. STScI Home. Retrieved May 6, 2022.

NASA. Imagine the universe! NASA. Retrieved May 6, 2022.

Boen, B. (2013, August 29). Supermassive black hole Sagittarius A*. NASA. Retrieved May 6, 2022.

NASA's Chandra Finds Intriguing Member of Black Hole Family Tree. Chandra X-ray Observatory. (2015, February 25). Retrieved May 6, 2022.

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Black holes: Everything you need to know

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Black holes are real, they're some of the strangest objects in space. Discover what black holes are and how they form with our informative black hole guide.

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Measuring the size of a star is very complicated because very small deviations in the calculation have a huge effect on its result.

Taking that into consideration one of the biggest stars currently known in our universe called WOH G64 is about 1,540 times the size of our Sun. This star is very interesting since around it there's a huge layer of dust that surrounds it.

Even though it's gigantic size this star is a lot cooler than our Sun, 3,100°C meanwhile the Sun has a surface temperature of around 5,226.85°C. This star when out of fuel will cause a huge supernova and can even become a black hole.

This shows how complex and unique stars are, and that proves that there isn't only one way of categorizing and defining stars.

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The New Largest Star in the Universe 2024! WOH G64

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All stars form in nebulae, which are huge clouds of gas and dust. Though they shine for many thousands, and even millions of years, stars do not last forever. The changes that occur in a star over time and the final stage of its life depend on a star's size.

Life Cycle of a Star
Credit:NASA

Nuclear reactions at the centre (or core) of a star provides energy which makes it shine brightly. This stage is called the ' main sequence'. The exact lifetime of a star depends very much on its size. Very massive stars use up their fuel quickly. This means they may only last a few hundred thousand years. Smaller stars use up fuel more slowly so will shine for several billion years.

Eventually, the hydrogen which powers the nuclear reactions inside a star begins to run out. The star then enters the final phases of its lifetime. All stars will expand, cool and change colour to become a red giant. What happens next depends on how massive the star is.

A smaller star, like the Sun, will gradually cool down and stop glowing. During these changes it will go through the planetary nebula phase, and white dwarf phase. After many thousands of millions of years it will stop glowing and become a black dwarf.

A massive star experiences a much more energetic and violent end. It explodes as a supernova. This scatters materials from inside the star across space. This material can collect in nebulae and form the next generation of stars. After the dust clears, a very dense neutron star is left behind. These spin rapidly and can give off streams of radiation, known as pulsars.

If the star is especially massive, when it explodes it forms a black hole.

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All stars form in nebulae, which are huge clouds of gas and dust. Though they shine for many thousands, and even millions of years, stars do not last forever. The changes that occur in a star over time and the final stage of its life depend on a star's size.

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A planetary nebula is a region of cosmic gas and dust formed from the cast-off outer layers of a dying star. Despite their name, planetary nebulae have nothing to do with planets.

When stars with an intermediate mass (greater than 80% of the Sun's mass, but less than eight times its mass) die, they expand to form red giants. The dying star will continue to expel gas, whilst simultaneously the remaining core of the star contracts and temporarily begins to radiate energy again. This energy causes the expelled gas to ionise, meaning that the atoms and molecules in the gas become charged and begin to emit light. The cast-off glowing gas is known as a planetary nebula. Therefore, planetary nebulae are classified as emission nebulae, and are entirely unrelated to planets. The misnomer came about because of a historical misclassification. 250 years ago, astronomers thought they were looking at gas planets when they observed the colourful spectacle of planetary nebulae through their less powerful telescopes. Planetary nebulae only last for about 20 000 years, making them a very short-lived part of the stellar life cycle.

Throughout the years, Hubble has studied and imaged varying shapes and colours of these intricate planetary nebulae, the different colours arising from different, often newly created, chemical elements, showing that the final stages of the lives of stars are more complex than once thought. You can explore Hubble's beautiful collection of planetary nebula images here.

Using Hubble, astronomers caught a rare glimpse of the nebula Hen 3-1357, nicknamed the Stingray nebula, fading precipitously over just the past two decades. Even though the Universe is constantly changing, most processes are too slow to be observed within a human lifespan. However, the Stingray Nebula offered researchers a special opportunity to observe the evolution of a system in real time. Images captured by Hubble in 2016, when compared to Hubble images taken in 1996, showed a nebula that has drastically dimmed in brightness and changed shape.

To celebrate Astronomy Day in 2003, astronomers unveiled one of the largest and most detailed celestial images to date of the Helix Nebula. The Hubble Space Telescope image showed a fine web of filamentary 'bicycle-spoke' features embedded in the colourful red and blue gas ring that is one of the nearest planetary nebulae to Earth. Being so nearby, the nebula is nearly half the size of the diameter of the full Moon. Hubble astronomers took several exposures with the Advanced Camera for Surveys to capture most of it.

Hubble's studies of a large number of planetary nebulae have also revealed that rings, such as those seen around the Cat's Eye Nebula, are much more common than previously thought and have been found in at least a third of all planetary nebulae.

The telescope also demonstrated its full range of imaging capabilities with two new images of planetary nebulae in 2020, of NGC 6302, dubbed the Butterfly Nebula, and NGC 7027. Both are among the dustiest planetary nebulae known and both contain unusually large masses of gas, which made them an interesting pair for study in parallel by researchers. The Hubble images revealed in vivid detail how both nebulae are splitting themselves apart on extremely short timescales - allowing astronomers to see changes over the past couple of decades.

Images

Word Bank: Planetary Nebula

Videos

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A planetary nebula is a region of cosmic gas and dust formed from the cast-off outer layers of a dying star. Despite their name, planetary nebulae have nothing to do with planets. When stars with an intermediate mass (greater than 80% of the Sun's mass, but less than eight times its mass) die, they expand to form red giants.

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Clouds of dust and gas, where stars are born. Gravity presses together all these particles and then eventually a star is formed.

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Neutron stars are what's left of a star after a supernova, this type of star is one of the denser elements ever observed. They have very specific characteristics such as the fact that they tend to spin very fast and that they have what seems like a lighthouse. The collision of two Neutron Stars is so strong that it can generate a black hole, together with generating all of the heavier elements in the periodic table.

The core of this star is formed by protons and electrons that were forced together and because of that became neutrons.

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What makes a star shine?

A star shines because of the fusion of the elements (nuclear fusion) in its core, this fusion emits a lot of energy, consequently making the star bright and hot.

Hydrogen fusion generates Helium.

When the star runs out of Hydrogen to fuse it starts to use Helium (Carbon and Oxygen) and since it is a stronger energy the force of gravity gets weaker and that causes the core to swell and expand. Then because of that, the star becomes what we call a Red Giant.

Incredibly, the only thing that holds stars together is gravity and without it they wouldn't even be formed.

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The death of a star.

At this moment the star explodes and then leaves behind a nebula from which a lot of different things can be formed.

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Red Dwarfs -> White Dwarfs

Main Sequence Stars (Sun) {a lot brighter and hotter} -> Red Giant -> White Dwarf + Planetery Nebula

Massive Stars -> Hypergiants (Blue and Yellow) -> Supernova + Neutron Star or (if big enough) Black Hole

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Neutron Stars – The Most Extreme Things that are not Black Holes

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A process where atoms are joined and tremendous amounts of energy are released.

This is the process that causes the star to shine and basically what keeps it alive.

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The Life and Death of Stars: White Dwarfs, Supernovae, Neutron Stars, and Black Holes

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When theres a change in the DNA or in the RNA that causes a mutation, but some of those mutations are neutral meaning that the amino acid doesn't change because even though the code changed it didn't affect the result. The mutation could also be helpful, so it can give the being an advantage that may be passed on to their offspring and thats how natural selection starts

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Alleles are basically what decides your visible traits (phenotypes) such as hair color, eye color, etc. These genes can be recessive or dominant.

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Each cell is formed by 46 chromosomes which means 23 pairs. Diploid are two sets of chromosomes that are in almost every cell except the gametes. The gametes are the reproductive cells in our bodies, the female cell is called egg or ovum while the male cell is called sperm and each gamete only has 23 chromosomes. Zygote is the combination of an egg and a sperm, so after the egg is fertilized, that forms an embryo.

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Living things pass through a process that's called natural selection which basically means that beings that are more adapted to their habitat tend to survive more which means that those traits will be passed down and become more common within the species, natural selection basically what makes living beings evolve. That's why humans are so different from one another, for example, skin color; if you have a darker skin tone that means that you have more eumelanin and that makes you more protected from UV rays but it's harder to get vitamin D in less sunny places. Meanwhile, if you have a lighter skin tone you have more pheomelanin which makes it easier for you to get vitamin D in less sunny places but you tend to be more sensitive to stronger UV rays.

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DNA is a type of molecule, meaning that it's formed from a bunch of atoms stuck together. DNA is a very long strand that is kept rolled up around histones (a type of protein) this is called a chromosome and it's located inside the genome which is inside the nucleus of a cell.
All living things have DNA and it is formed by genes these genes are the instructions meaning that the DNA is basically the instruction book to make parts of you. For that process to happen a strand of messenger RNA is created by a transcription of the actual DNA and moves out of the nucleus of the cell into the cytoplasm there the transfer RNA comes from every three genes it creates an amino acid, which later becomes a chain of amino acid which is what forms a protein.

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Quarks are even smaller particles and because of that they're called subatomic and they make up of neutrons and protons. There are different types of quarks; up quarks and down quarks, to form a proton you need two up quarks and one down quark while for a neutron are two down quarks and one up quark.

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Punnet squares are a way to see the probability of a trait being passed down by analyzing the parents and the 'probability' of that trait. For example, some traits tend to overpower like the Y there's one of each but it's still yellow because the yellow gene is dominant while the green is recessive.
After you create the punnet square then you can create a table with genotype, phenotype, and probability so you can see how likely it is for a person to get a certain trait.

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Atoms are the building blocks for everything, from matter to air all its formed by this single thing. Atoms are made up of protons, neutrons, and electrons.
The nucleus even though it's the smallest part of the atom it has most of the atom's mass. But since everything is made from atoms the way they differentiate iron from gold for example is that the type of atom is different. Each different atom is called an element and they're all found in the periodic table, the difference between them is the number of protons. For example, titanium contains a total of twenty-two protons while hydrogen has only one.

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Since the only difference is the amount of melanin in our skin it makes no sense for people to consider themselves different from a person with a different skin tone. Not only that but since we're all made from literally the same things.

Pyramid of hate - we're all made of atoms, and human differences came from natural evolution, melanin in the skin

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Electrons are located in the electron cloud and they have a negative charge.
If the number of electrons isn't balanced with the number of protons the atom becomes unstable and it's called an ION.

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Protons are located in the nucleus and they have a positive charge.
If an extra proton is added to the atom the element will change.

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Neutrons are located in the nucleus and they have a neutral charge (neither positive nor negative).
If an atom contains an extra neutron that means this atom is an isotope which means that it's still the same element.

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https://www.youtube.com/watch?v=PTUbPTy8SWg

https://youtu.be/neMEo8ZrwuI

https://www.youtube.com/watch?v=fgQLyqWaCbA

Khan academy

https://www.youtube.com/watch?v=_lNF3_30lUE

https://www.youtube.com/watch?v=LhveTGblGHY

https://www.youtube.com/watch?v=ooWfzpUIoNM

https://www.youtube.com/watch?v=C0Qaf-UJ2XQ

https://www.youtube.com/watch?v=4WR0_gEEZ9I

https://www.youtube.com/watch?v=UtZw9jfIxXM

https://www.youtube.com/watch?v=UtZw9jfIxXM

https://www.youtube.com/watch?v=gG7uCskUOrA

https://www.youtube.com/watch?v=joTKd5j3mzk

https://www.youtube.com/watch?v=zwibgNGe4aY

https://www.jax.org/news-and-insights/minute-to-understanding/what-is-an-allele

https://www.biologyonline.com/dictionary/protein-synthesis#:~:text=Protein%20synthesis%20is%20the%20creation%20of%20proteins%20by%20cells%20that,folding%2C%20modifications%2C%20and%20proteolysis

https://www.youtube.com/watch?v=Mehz7tCxjSE

# data[].attributes.body
The Big Bang is the theory in the universe started from a single point that later on expanded until it got to the size it is today. This explosion is estimated to have happened around eight billion years ago. What happened was that it all started in a single point that expanded and grew as large as the universe is right now, a little time after the big bang the universe was really hot and dense, quarks and electrons had no mass. Then something called the Higgs Field interacted with them and gave them their mass but that's not what happens to all particles, for example, photons have no mass but they also don't interact with the field meaning that they won't gain mass, particles gain their mass depending on how it interacts with the field it and that makes it gain more or less mass.  After that protons, neutrons, and electrons formed H and He nuclei. All this took less than a second after the explosion. Next, it took millions of years before atoms were formed. The first ones to be formed were the elements H and He since they have fewer protons and energy.