Asteroids are balls of rock a few feet

• Asteroids are balls of rock a few feet to several miles in diameter. • The are not large enough to be considered planets. • The total mass of all asteroids are less than the mass of the moon. • Thousands are discovered, but only 26 known asteroids are 200 km in diameter.

• The largest asteroid by far is 1 Ceres. • It is 974 km in diameter and contains about 25% of the mass of all the asteroids combined. • The next largest are 2 Pallas, 4 Vesta and 10 Hygiea which are between 400 and 525 km in diameter. • All other known asteroids are less than 340 km across. •

• This asteroid almost hit Earth when Italian astronomers were ready to catch it on film.

• Most asteroids orbit a belt between Jupiter and Saturn. • The belt contains hundreds of thousands of asteroids ranging from different sizes

• Asteroids are sometimes metallic and come in three different forms. • There are classified as c-type, stype, and m-type.

• More than 75% of asteroids are classified as c-type, or carbonaceous. • M-type, or metallic are made up of metallic iron.

• S-type, or siliceous asteroids make up about 17% of all asteroids. • Asteroids are measured by units of measure that record the amount of light they reflect. These are known as albedos. • They range from 0 -1, 1 being the brightest.

• Comets and asteroids have similarities and differences. • Asteroids are usually made of only rock or iron. • Comets have more of a chemical makeup.

• If comets are heated up, they will vaporize. • Like asteroids, comets have no atmosphere. • Comets however are more egg shaped, where as asteroids can be some irregular shapes.

• A cool way to tell comets and asteroids is that when a comet passes by, it looks fuzzier than an asteroid when your using an asteroid.