Galaxy

GALAXIES

1. WHAT IS A GALAXY?

Ans: Our Sun is just one of a massive collection of 200 billion stars arranged in a shape like a fried egg, 100,000 light-
years across. This collection is called the Galaxy, because we see it in the band of stars across the night sky called the Milky Way. (Galaxy comes from the Greek for milky.) But earlier this century it was realized that the Galaxy is just one of billions of similar giant star groups scattered throughout space, which we also call galaxies. The nearest is the Andromeda galaxy.

2. WHAT ARE STAR CLUSTERS?

Ans: Stars are rarely entirely alone within a galaxy. Most are concentrated in groups called clusters. Globular clusters are big and round. Galactic clusters are small and formless.

3. HOW MANY GALAXIES ARE THERE?

Ans: There are currently estimated to be about 125 billion galaxies in the universe – there may be many, many more than this.

4. WHAT IS THE MILKY WAY?

Ans: The Milky Way is a pale, blotchy, white band that stretches right across the night sky. From Earth you only get an edge-on view of the Milky Way. A powerful telescope shows it is made up of millions of stars.

5. WHAT ARE DOUBLE STARS?

Ans: Our Sun is alone in space, but many stars have one or more nearby companions. Double stars are called binaries.

7. WHAT IS A SPIRAL GALAXIES?

Ans: A spiral galaxies are galaxies that has spiralling arms of stars like a gigantic Catherine wheel. They trail because the galaxy is rotating Our Galaxy is a spiral galaxy.

8. WHAT IS THE BIGGEST THING IN THE UNIVERSE?

Ans: The biggest structure in the universe is the Great Wall -a great sheet of galaxies 500 million light-years long and 16 million light-years thick.

9. WHERE IS THE EARTH?

Ans: The Earth is just over half way out along one of the spiral arms of the Galaxy, about 30,000 light-years from the center.

10. WHAT EXACTLY ARE NEBULAE?

Ans: Nebulae are giant clouds of gas and dust spread throughout the galaxies. Some of them we see through telescopes because they shine faintly as they reflect star With others, called dark nebulae, we see only inky black patches hiding the stars behind. This is where stars are born . A few, called glowing nebulae, glow faintly of their own a as the gas within them is heated by nearby stars.

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