Asteroid
Belt
by Ashley
Asteroid
Belt
by Ashley
Asteroids are small bodies that are believed to be left over from the beginning of the solar system billions of years ago. They are rocky, have irregular shape and can be several hundred kilometers wide. More then 100,000 asteroids lie between Mars and Jupiter. This is called the asteroid belt. Scientist think that the asteroid belt was formed when an early planet broke apart.
The first asteroid was discovered on the first day of January in 1801, by a man named Gisueppe Piazza. The asteroid was mistaken for a comet but once it's orbit was better viewed it look like a small new planet. They named this asteroid Ceres. A few years later they found three other small bodies named Pallas, Vesta, and Juno. At the end of the 19th century there were several hundred small bodies. Thousands of asteroids are discovered each year. There are thousands or millions more asteroids in space that are too small to be seen from earth. There are only 26 asteroids that have been discovered that are 200 kilometers in diameter. Scientists have discovered 99% of asteroids that are 10 kilometers in diameter. We have discovered more than a million asteroids that have 1 kilometer in range.
Asteroids are "boulders in space" because they are look like big chunks of rock that are floating in space. All these asteroids have there own orbit around the Sun. Some astronomers believe that in this big gap where the Asteroid Belt is that there was a rocky planet that hit another planet and broke up into millions of pieces. Other astronomers believe that asteroids began to form from the other materials that were left over after the solar system was formed.
Asteroids are classified into three different groups. There are more than 75% of C-type asteroids known to mankind. There are 17% of asteroids made of metallic, nickel, and iron mixed in with magnesium and sillicates(S-type). The other asteroids we have found are made of pure nickel and iron. Out of the three main groups asteroids are broken into smaller groups. Here are a few names of the main asteroids in the asteroid belt Themis, Floras, Phocaea, Koronis, Eos, Hungarais, Cybeles and Tlildas. All these asteroids have a size. Most of the asteroids in the asteroid belt are a few hundred feet to several of miles big. Ceres is the largest asteroid and is over 360 miles in diameter.
Every once and awhile comets or gravitational pull will knock out an asteroid out of the asteroid belt. Sometimes some of the little pieces broken off of asteroids will get close enough to earth to be pulled into Earth's atmosphere and becomes what we call a meteoroid. Aten is a asteroid that has been close to Earth. Aten is less then 1.0 and has a distance greater than 0.983. Apollo is another asteroid that has come close to Earth and Apollo's axis is greater than 1.0 and has a distance that is less than 1.017. Amor is the last recorded asteroid that got close to Earth. Amor's distance is between 1.017 and 1.3.
A few asteroids and comets are listed below for comparison. (distance is the mean distance to the Sun in thousands of kilometers; masses in kilograms).
Number Name Diameter Radius Length Discoverer Year
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http://www.nineplanets.org/asteroids.html
http://www.seasky.org/cosmic/sky7a04.html
Asteroid Pictures:
http://www.nineplanets.org/asteroids.html
http://www.solarviews.com/eng/asteroid.htm
http://www.windows.ucar.edu/tour/link=/our_solar_system/asteroids.html