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The Night Sky. A constellation is a grouping of stars that has a name and forms a pattern . . The word constellation can also mean the region of the sky surrounding one of those patterns of stars .
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A constellation is a grouping of stars that has a name and forms a pattern. • The word constellation can also mean the region of the sky surrounding one of those patterns of stars. • The sky is divided into 88 constellations so that any point in the sky can be said to belong one of these 88. • Many of these modern constellations have their roots in ancient Greek mythology, and their names and stories reflect that.
Constellations • A constellation is an imagined pattern of stars. • Most look like objects or living things. • A pattern is something that happens in a regular way you can predict, or guess. (Regular shapes such as squares and triangles can also form patterns). • Egyptians and ancient Chinese people described constellations thousands of years ago. • Almost 2000 years ago, the Romans described and named 48 constellations. Those are the names and star patterns we talk about today.
Ursa Major is a constellation that people thought looked like a bear. Ursa Major is Latin for “big bear”.
People sometimes use stars and constellations to find directions. • For example, take the star Polaris. It is part of the constellation Ursa Minor, or the “little bear”. Ursa Minor is also called the Little Dipper. • In the night sky, Polaris is above the North Pole. • People in the northern half of Earth use Polaris to find where north is.
Polaris is also called the North Star. It appears to be above Earth’s North Pole. If you face Polaris, you are facing north. To your right is east. To your left is west. And behind you is south.
Cassiopeia was the vain queen who boasted of her beauty and Cepheus was her husband. • Together their constellations appear in the northern sky close to Ursa Minor (the Little Dipper).
The star pattern known as the Big Dipper is actually an asterism, meaning it is a grouping of stars that is widely known and recognized, but is not an official constellation. • The Big Dipper is actually part of the constellation Ursa Major, the bear.
All of these constellations have one thing in common, and that is they are circumpolar • Circumpolar means they rotate closely around Polaris (the North Star) and are visible for much of the year from the northern hemisphere.
Our Earth is not the center of the solar system. • The stars are not fixed, but scattered across the galaxy and beyond at differing distances from Earth.
Stars and Planets • Stars and Planets both look like tiny points of light to us on Earth, but how they seem to move is different. • The pattern of stars in a constellation stays the same. However, you can see a planet in different places at different times compared to the stars. • The sun is the closest star to Earth. • Other stars are so far away that they seem to be fixed in place compared to each other. For example, we always see Polaris in the same place in the Little Dipper.
The other planets in our solar system are much closer to Earth than the stars are. They move around the sun like Earth does. • So to us on Earth, planets appear to move across the pattern of stars in the night sky. • You cannot see them move in one night, but you can see the planets move if you watch the sky for weeks or months. • .
Their relative positions never appear to change because they are so far away from Earth. • The nightly movement and seasonal changes in the visible stars come from Earth’s rotation and revolution around the sun.
Ancientpeople noticed that planets move from one place to another. • People have watched the way Mercury, Venus, Mars, Jupiter, and Saturn move for thousands of years. In fact, the word planet comes from a word that means “wanderer”. • A scientist who studies objects in space, like moving planets, is called an astronomer
Discussion Question How do you think sailors on the ocean long ago used star patterns? What do modern sailors use for this purpose?
Lesson Review • What is a constellation? a. A pattern of planets b. A pattern of stars c. A star d. A scientist who studies objects in space.
Which object can you always find above the North Star? a. Mars b. Polaris c. Saturn d. Venus
What did ancient astronomers notice about Mercury and Mars? a. They form constellations. b. They are found just above the North Pole c. They do not move across the night sky. d. They move across the night sky.
