Five Astronomical Things
1. Star
Stars are huge masses of burning chemical gases, mostly helium and hydrogen that are light years away. It takes millions of years for a star to form from clouds of dust and gas. Their formation usually begins from some disturbance in the gravitational field. They glow as a result of the fusion of hydrogen into helium. After billions of years, the star runs out of hydrogen and dies. Our sun is a star. To learn more about the life of a star, click here. |
2. Nebula
A nebula is a cloud of dust and gas. The gas is mostly hydrogen with some helium. As the clouds collapse from the pull of gravity, stars are formed. To see a cool video on the Orion Nebula as seen through the Hubble Space Telescope, click here. |
3. Red Giant
A red giant is a low mass star that has used up its supply of hydrogen in its core so that thermonuclear fusion of hydrogen is now occurring in a shell that surrounds the core. This process expands the size of the star. Red giants are huge, hundreds of times bigger than the sun. |
4. White Dwarf
As a low mass star continues to die off, it sheds its outer layers and becomes very dense. At this stage, near the end of its life, it is called a white dwarf. The picture to the left shows the bright star Sirius A. If you look in the lower left corner, you can see a little pinprick of light. Can you find it? That pinprick is the white dwarf called Sirius B. |
5. Black Hole
Black holes are formed when large mass stars die. As the fuel of a star burns out, gravity pulls inward. The core of the star becomes extremely compressed. The gravity of the core is so strong, that not even light can escape, causing the object to disappear from view. |