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Constellations and Basic Information About Them

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Constellations and Basic Information About Them

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Overview
In contemporary astrology, there are 88 constellations that are recognized by the International Astronomical Union. 42 depict animals, 29 depict inanimate objects and 17 depict humans or mythological characters.
The ancient Sumerians, Babylonians, and later, the Greeks established the majority of the northern constellations that are officially recognized today. That is why many stars and constellations are connected to ancient myths and legends. For example, the Lyre constellation represents the celestial harp created by Hermes and gifted to Orpheus by Apollo. When Orpheus played love songs to his beloved bride Eurydice, both people and animals would become captivated. When Eurydice died suddenly, Orpheus' enchanting lyre music convinced the ruler of the underworld to release Eurydice under the condition that Orpheus does not look back at her as she followed him out to the surface. Unable to endure the doubt that she was not behind him, he glanced over his shoulder and witnessed Eurydice fade away back into Hades' domain. After Orpheus passed away, Zeus placed his lyre in the stars in honor of his beautiful music and forsaken love.

Egyptians and the Zodiac
The ancient Egyptians are believed to have developed the Zodiac system, which was later adopted by the Babylonians.
Early astrologers understood that it took 12 lunar cycles for the sun to return to its original position. They then identified 12 constellations that correlated with the progression of the seasons and named them after certain animals or people. These became the Zodiac signs. The Zodiac signs are divided into four groups. Fire signs include Aries, Sagittarius, and Leo. Water signs include Cancer, Scorpio, and Pisces. Air signs include Libra, Aquarius, and Gemini. Earth signs include Capricorn, Taurus, and Virgo. Babylonian astrologers believed that the Sun, Moon, and five known planets (Jupiter, Mars, Mercury, Saturn, and Venus) imbued distinct powers onto each Zodiac constellation.

Top 10 Constellations
The largest constellation is the Hydra, which takes up 3.2% of the Southern night sky. It is commonly depicted as a water serpent. The best time to see Hydra is in January. The top 10 largest constellations are as follows:

1. Hydra - 3.2%

2. Ursa Major - 3.1%

3. Virgo - 3.1%

4. Cetus - 3%

5. Hercules - 3%

6. Eridanus - 2.8%

7. Pegasus - 2.7%

8. Centaurus - 2.6%

9. Draco - 2.6%

10. Aquarius - 2.4%

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The 88 Constellations and Their Brightest Stars | Sleepopolis

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Looking to learn more about constellations for kids? Improve your knowledge on stars and constellations and find out more about space with DK Find Out.

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Constellation Types, Names, and Where They Are

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Constellation Types, Names, and Where They Are

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Constellations for Kids | Learn about the types of constellations, their names, and how to find them

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How to Make Up Your Own Star Constellation: 10 Steps

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For millennia people have looked to the stars as a way of navigating across oceans and land or to mark the changing of the seasons. They have created constellations as familiar, reassuring beacons to guide them along their journeys. Now…

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What is the Current Phase of the Moon?

What are Lunar Phases?

What Are Lunar Phases?

Our Moon doesn't shine, it reflects. Just like daytime here on Earth, sunlight illuminates the Moon.

Credit: NASA/Bill Dunford

We just can't always see it.

When sunlight hits off the Moon's far side - the side we can't see without from Earth the aid of a spacecraft - it is called a new Moon.

When sunlight reflects off the near side, we call it a full Moon.

The rest of the month we see parts of the daytime side of the Moon, or phases. These eight phases are, in order, new Moon, waxing crescent, first quarter, waxing gibbous, full Moon, waning gibbous, third quarter and waning crescent. The cycle repeats once a month (every 29.5 days).

What is a Lunar Eclipse?

What is a Lunar Eclipse?

During a lunar eclipse, Earth comes between the Sun and the Moon, blocking the sunlight falling on the Moon.

There are two kinds of lunar eclipses:

A total lunar eclipse occurs when the Moon and Sun are on opposite sides of Earth.

A partial lunar eclipse happens when only part of Earth's shadow covers the Moon.

During some stages of a lunar eclipse, the Moon can appear reddish. This is because the only remaining sunlight reaching the Moon at that point is from around the edges of the Earth, as seen from the Moon's surface. From there, an observer during an eclipse would see all Earth's sunrises and sunsets at once.

A composite of seven images shows the full Moon at perigee, or supermoon, during a total lunar eclipse on Sunday, Sept. 27, 2015, in Denver. Credit: NASA/Bill Ingalls

Understanding Lunar Eclipses

A lunar eclipse occurs when the Moon passes through the Earth's shadow, just as a solar eclipse occurs when part of the Earth passes through the Moon's shadow.

So why don't eclipses happen twice a month?

The reason is that the Moon's orbit around the Earth is tilted relative to the Earth's orbit around the Sun.

But if that's the case, why do eclipses happen at all?

Throughout the year, the Moon's orbital tilt remains fixed with respect to the stars, meaning that it changes with respect to the Sun. About twice a year, this puts the Moon in just the right position to pass through the Earth's shadow, causing a lunar eclipse.

As the Moon passes into the central part of the Earth's shadow, called the umbra, it darkens dramatically. Once it's entirely within the umbra, the Moon appears a dim red due to sunlight scattered through the Earth's atmosphere.

In fact, if you watched the eclipse from the surface of the Moon, you'd see the Sun set behind the entire Earth, bathing you in a warm red glow. Back home, you'll have to stay up late to watch a lunar eclipse, but if you do you'll see the Moon in rare form, and you'll catch a brief glimpse of our own planet's long shadow.

It's not often that we get a chance to see our planet's shadow, but a lunar eclipse gives us a fleeting glimpse. During these rare events, the full Moon rapidly darkens and then glows red as it enters the Earth's shadow. More details and download options ›
Photograph the Moon

Photograph the Moon

Capturing the Moon with a camera is one of the most satisfying-and challenging-projects available to an outdoor photographer. Here are 10 suggestions for making the most of a moonlit night with your camera.

How do Lunar Eclipses Affect Spacecraft?

How do Lunar Eclipses Affect Spacecraft?

Lunar eclipses can be a science boon and engineering challenge for orbiting spacecraft, such as NASA's Lunar Reconnaissance Orbiter. The solar-powered orbiter also falls in Earth's shadow, cutting it off from the source of its power. Mission controllers shut down most instruments to conserve energy.

The team leaves on one instrument-called Diviner-that can watch how the lunar surface responds to the rapid change in temperature caused by a lunar eclipse. The data helps scientists better understand the composition and properties of the surface.

Additional Resources

Eclipse Videos

Eclipse Activities

How to watch an eclipse and get students observing the Moon

Evaluating a Lunar Eclipse (Grades 3-12) - Students use the Danjon Scale of Lunar Eclipse Brightness to illustrate the range of colors and brightness the Moon can take on during a total lunar eclipse.

Observing the Moon (Grades K-6) - Students identify the Moon's location in the sky and record their observations in a journal over the course of the Moon-phase cycle.

Moon Phases (Grades 1-6) - Students learn about the phases of the Moon by acting them out. In 30 minutes, they will act out one complete, 30-day, Moon cycle.

Measuring the Supermoon (Grades 5-12) - Students take measurements of the Moon during its full phase over multiple Moon cycles to compare and contrast results.

Modeling the Earth-Moon System (Grades 6-8) - Students learn about scale models and distance by creating a classroom-size Earth-Moon system.

Make a Moon Phases Calendar and Calculator - Like a decoder wheel for the Moon, this calendar will show you where and when to see the Moon and every Moon phase throughout the year!

Explore More

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Lunar Phases and Eclipses | Earth's Moon - NASA Solar System Exploration

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What is the Current Phase of the Moon? What are Lunar Phases? Our Moon doesn't shine, it reflects. Just like daytime here on Earth, sunlight illuminates the Moon. We just can't always see it. When sunlight hits off the Moon's far side - the side we can't see without from Earth the aid of a spacecraft - it is called a new Moon.

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WHAT CAUSES DAY AND NIGHT ? || SCIENCE VIDEO FOR KIDS

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The map above shows where on Earth it is currently day time, night time, or twilight.

Hovering the mouse over any location on the map will show the map will show the altitude of the Sun as seen from that location.

The thick yellow line shows where sunset and sunrise are currently occurring. The thinner lines lines show the boundaries of civil, nautical or astronomical twilight respectively. The Sun icon shows where on Earth the Sun is seen directly overhead.

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Live map of where it is daytime, twilight or night time

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The map above shows where on Earth it is currently day time, night time, or twilight. Hovering the mouse over any location on the map will show the map will show the altitude of the Sun as seen from that location. The thick yellow line shows where sunset and sunrise are currently occurring.

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Why Do We Have Different Seasons? | California Academy of Sciences

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US Department of Commerce, NOAA, National Weather Service

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Our World: Sun's Position | Our World | NASA eClips

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Find out more about how our sun's position in the sky changes due to Earth's rotation, revolution and tilt. Learn from the experts -- Dr. Alex Young and Dr. Nicki Viall explain these connections so students understand patterns within the Earth-sun relationship.

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Stellarium Web is a planetarium running in your web browser. It shows a realistic star map, just like what you see with the naked eye, binoculars or a telescope.

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It's all about Earth's tilt!

Many people believe that Earth is closer to the Sun in the summer and that is why it is hotter. And, likewise, they think Earth is farthest from the Sun in the winter.

Although this idea makes sense, it is incorrect.

It is true that Earth's orbit is not a perfect circle. It is a bit lop-sided. During part of the year, Earth is closer to the Sun than at other times. However, in the Northern Hemisphere, we are having winter when Earth is closest to the Sun and summer when it is farthest away! Compared with how far away the Sun is, this change in Earth's distance throughout the year does not make much difference to our weather.

There is a different reason for Earth's seasons.

Earth's axis is an imaginary pole going right through the center of Earth from "top" to "bottom." Earth spins around this pole, making one complete turn each day. That is why we have day and night, and why every part of Earth's surface gets some of each.

Earth has seasons because its axis doesn't stand up straight.

But what caused Earth to tilt?

Long, long ago, when Earth was young, it is thought that something big hit Earth and knocked it off-kilter. So instead of rotating with its axis straight up and down, it leans over a bit.

By the way, that big thing that hit Earth is called Theia. It also blasted a big hole in the surface. That big hit sent a huge amount of dust and rubble into orbit. Most scientists think that that rubble, in time, became our Moon.

As Earth orbits the Sun, its tilted axis always points in the same direction. So, throughout the year, different parts of Earth get the Sun's direct rays.

Sometimes it is the North Pole tilting toward the Sun (around June) and sometimes it is the South Pole tilting toward the Sun (around December).

It is summer in June in the Northern Hemisphere because the Sun's rays hit that part of Earth more directly than at any other time of the year. It is winter in December in the Northern Hemisphere, because that is when it is the South Pole's turn to be tilted toward the Sun.

Earth's lopsided orbit

Earth's perihelion (point closest to Sun) = 91,400,000 miles from Sun

Earth's aphelion (point farthest from Sun) = 94,500,000 miles from Sun

While that is a difference of over 3 million miles, relative to the entire distance, it isn't much.

And, believe it or not, aphelion (when Earth is farthest from the Sun) occurs in July, and perihelion (when we are closest) occurs in January. For those of us who live in the Northern Hemisphere where it's summer in July and winter in January, that seems backwards, doesn't it? That just goes to prove that Earth's distance from the Sun is not the cause of the seasons.

Related Resources for Educators

Seasons (Educator Guide to go with Seasons Spotlite video)
Seasons (Nearpod Lesson to go with Seasons Spotlite video)
Our World: Sun's Position
Sun's Position (Educator Guide to go with Sun's Position Spotlite video)
Sun's Position (Nearpod Lesson to go with Sun's Position Spotlite video)

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Moon Phases Simulation Viewed from Earth and Space | PBS LearningMedia

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Relate observable Moon patterns to motions within the Earth-Sun-Moon system using this digital model from Astronomy Education at the University of Nebraska-Lincoln. Linked Earth and space perspectives enable students to recognize cause-and-effect relationships. They can also visualize the spatial and time scales of phenomena such as the Moon's apparent path in the sky and the Moon's appearance in the day sky and night sky.

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Constellation Location: Crash Course Kids #31.2

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The Movements of Earth - Understanding Day and Night, Summer and Winter |Earth Rotation Revolution

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Seasons and the Sun: Crash Course Kids 11.1