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WHAT IS A GALAXY?

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A galaxy is a largegroup of stars

bound together by gravity.

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How many solar systems are there in our galaxy? Astronomers have found about 70

SOLAR SYSTEMS and are discovering new ones every year.

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There are three kinds of galaxies.

Spiral

Elliptical

Irregular

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Spiral galaxiesPictures by the Hubble Space Telescope

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Elliptical galaxies

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Irregular galaxies

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Our Milky Way Galaxyis a spiral galaxy.

We think! This is not really a

picture of our galaxy – just one that looks like what we think our galaxy is like!

Our Solar System is supposed to be in the Orion Arm!

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Structure of the

Milky Way

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Top view

Side view

Can you see our Solar System?

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Every star we see in the night sky is in our own galaxy.

We cannot see stars in other galaxies because they are too far away.

The Milky Way is estimated to have 200 billion stars.

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A constellation isa group of stars

than appear to be together but are not.They seem to form a picture in the sky.

People use them to find their way around the sky .

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LET’S SEE SOME EXAMPLES OF CONSTELLATIONS

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Orion the hunter

The constellation looks flat but all the stars are at different distances from us.

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Leo the Lion

Cygnus the Swan

Can you see the drawing?

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Scorpio

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The Zodiac is a special group of constellations that extend out from Earth’s equator.