Meteors are commonly called falling stars or shooting stars. If any part of the meteoroid survives burning up and actually hits the Earth, that remaining bit is then called a meteorite. At certain times of year, you are likely to see a great number of meteors in the night sky.

Most meteors glow for only a few seconds prior to burning up before hitting the Earth's surface. On most dark nights, meteors can be seen. The chance of seeing a meteor with the unaided eye increases after midnight. People often refer to meteors as "falling" or "shooting" stars. The brightest of the meteors are called fireballs.

This photograph shows one of the meteorites which survived the "Chicago Fireball".

If you have ever seen a "falling star", you were actually seeing a meteor. Most of the original object burns up before it strikes the surface of the Earth. Any leftover part that does strike the Earth is called a meteorite. A meteorite can make a hole, or crater, in the ground when it hits it. The larger the meteorite, the bigger the hole.

The Oort Cloud is believed to surround our solar system and reach over halfway to the nearest star, Alpha Centauri, which is 150,000 astronomical units away. Scientists think that about 100 million comets orbit the Sun. A comet has a distinct center called a nucleus.

Star watching has occupied humans from the earliest times. Our ancestors studied the night sky and saw shapes and patterns among the stars. They often made up stories to explain what they saw. The same star constellation was seen very differently by people from different countries, or even different parts of the same country.

To our eyes, this makes the star seem to twinkle. You will notice that stars closer to the horizon will appear to twinkle more than other stars. This is because there is a lot more atmosphere between you and a star near the horizon than between you and a star higher in the sky. Go out some night soon and have a look!

An asteroid is a rocky body in space which may be only a few hundred feet wide or it may be several hundred miles wide.

Quasars give off huge amounts of energy. They can be a trillion times brighter than the Sun! Astronomers think that quasars are located in galaxies which have black holes at their centers.

Passing by the comet at a velocity of 68 km/second, the spacecraft suffered some damage. Some of the instruments no longer worked or were only partially functional. The star mapper's baffle was peppered with holes. Subsequent analysis of Giotto's data showed that water accounted for about 80% of all of the material being thrown out by the comet.