1. Why do the sunrise and set?
Actually, it doesn’t! The sun always shines. It just looks as if it rises and sets every day. Earth spins around or rotates all the time. When your part of Earth turns towards the sun, it seems to rise. When your part of Earth rotates away from the sun, it seems to set. (Space…)
The sun does not rise and set. It just looks that way because we are seeing the sun from a turning Earth.
2. Is each star alone in space?
No. Every star belongs to a large group of stars called a galaxy. Each galaxy has between a billion and a trillion stars. And there are about 50 billion galaxies throughout the universe.
Our sun is part of a galaxy called the Milky Way. Astronomers say that the Milky Way galaxy contains 100 billion stars.
When you look upon a clear dark night, you can see part of the Milky Way. It is a band of hazy white light across the sky. To people long ago it looked like a splash of milk, so they named it the “Milky Way.”
3. How big is the Milky Way galaxy?
Too big to be easily measured in miles. Instead, astronomers measure the distance in light-years. A light-year is a distance that light, which movies at 186000 miles a second., travels in one year. A light-year is just less than 6 trillion miles. The distance across the Milky Way galaxy is about 10000 light-years or 6 million billion miles.
4. Is the sun near the centre of our galaxy?
No. The sun is off to one side.
Our galaxy is shaped like a gigantic pinwheel with a bulge in the centre. The Arms of the pinwheel extend out from the bulge. The sun is in one of the arms. It is about 33000 light-years from the centre.
The sun and all the stars revolving around the centre of the galaxy. The sun travels at a speed of about 156 miles a second. At that speed. it takes 250 million years for the sun to complete one giant loop around the Milky Way.
5. Can we see other galaxies besides the Milky Way?
We can see three other galaxies without a telescope. Each looks like a hazy patch of light in the night sky.
From the Northern Hemisphere, we can see the Andromeda galaxy. It is 2200000 light-years away. Andromeda is even bigger than the Milky Way galaxy in space.
From the Southern Hemisphere, we can see tow galaxies called the Large and Small Magellanic Clouds. They are respectively 160000 and 180000 light-years from Earth.
6. How far is the distant galaxy?
Scientists believe it is about 13 billion light-years away– a distance of 80,000,000,000,000,000,000,000 miles. Some say this may be the edge of the universe. Others believe the universe may not even have a boundary.
Astronomers know that all the galaxies in the universe are rushing away from each other today. But no one knew if this will continue forever or if they will start coming together in time.
7. Is a constellation the same as a galaxy?
No. A constellation is a group of perhaps a dozen bright stars– and many more stars that are not as bright–all in the same area of the sky. A galaxy, you know has billions of stars stretched over a much greater distance.
Long ago, people looked in wonder at the groups of stars that make up the constellations. In their minds, they drew lines joining the stars–just like connect-the-dot puzzles– to make pictures in the sky. Some of the pictures were of legendary figures, such as Hercules and Pegasus. Others were of animals, such as Taurus the bull.
Astronomers have divided the sky into 88 constellations. They use them to locate objects in the night sky, just as you sue addresses of locate houses. Constellations also help tell directions at night.
8. Are all the stars in a constellation the same distance from Earth?
Every star in a constellation is at a different distance from Earth. Some are closer; some are farther away. But as we look up, the points of light fool our eyes into believing that every star is the same distance from Earth.
Also, constellations are made up of stars of different brightness’s. Take Cygnus, the swan, for example. The star Deneb is a very bright star in the night sky in space. The rest of the swan is made up of fainter stars.
9. Do all people see the same constellations?
No. The constellations you can see will depend on where you live. Some constellations can only be seen in the Northern Hemisphere, other only in the Southern Hemisphere.
People who live on the equator are lucky. They can see all the constellations–but not all at once. It takes a whole year for all of the constellations to be visible from the equator.
10. Why is the North star important?
The North Star does not seem to move like the other stars. That’s because it is almost straight up over the North Pole. From the Northern Hemisphere, the North Star looks like it stays in one place in space.
Because the North Star seems fixed in the sky, sailors have long used it to help them find their way. The north star is also called Polaris or the polestar.
Check out the previous article about space and stars