Comets

Like asteroids, comets are more “junk” left over from the formation of the solar system. They are like giant snowballs. They have a small, solid nucleus. It is made of frozen gases and chunks of ice with rocks and dirt in them.

The most fascinating part of a comet is its tail. The tail is formed when the comet comes close to the sun. It begins to warm up. The ice turns to gases, which begin to glow. The solar wind blows these glowing gases away from the sun. We see them as a comet’s tail. They can flow for thousands of kilometers behind the comet’s core.

Most comets come from a distant ring of space garbage called the Oort Cloud. Like asteroids, comets also orbit the sun. Most of their orbits are farther away than Pluto. It can take some comets millions of years to make one orbit. Some, however, are close enough to see from Earth. When Earth passes through the tail of a comet, we see a meteor shower.

There have been space missions to both asteroids and comets. Scientists study them to get clues about how Earth evolved. For example, some believe that the impact of an asteroid caused a chain of events that led to the extinction of the dinosaurs here on Earth. Impacts from comets may have brought water to our planet. Scientists believe that these space rocks can tell us a lot about the formation of our solar system.

(Information taken from edhelper.com and Astronomy For Kids websites)
(Photo from http://static.howstuffworks.com/gif/comet-kohoutek.jpg)