SPACE ROCKS! By: Jordan, Keaton, and Vanessa

Asteroids ASTEROIDS Asteroids are rock fragments left over from the formation of the solar system about 4.6 billion years ago. Most asteroids orbit the sun in a belt between Mars and Jupiter. Scientists think there are probably millions of asteroids, ranging widely in size from hundreds of kilometers wide. Occasionally, asteroids’ orbital paths are influenced by the gravitational tug of planets, which cause their paths to alter. Scientists believe stray asteroids have slammed into the Earth in the past, playing a major role in the evolution of our planet.

METEORS AND METEORITES While traveling through space, asteroids sometimes collide with each other and end up breaking into smaller rock fragments. Comets shed dust as they fly through the solar system. These collisions result in numerous small particles and fragments, called meteoroids. Meteoroids are usually found orbiting the Sun. Most meteoroids are small and rocky; when they approach the Earth they burn up upon entering the atmosphere. This usually results in a meteor also known as a shooting star. Fireballs are larger meteoroids, roughly ranging in size from anywhere from a basketball to a Volkswagen beetle. They also make very impressive sky displays as they break into fragments and burn up on their journey through the atmosphere. Not all meteoroids burn up though; some make it through the atmosphere and impact the earth. These are called meteorites.

COMETS Comets are relatively small, fragile, irregularly shaped rocks, and often resemble asteroids in the sense that they are made from left over break offs from the solar system formation. Comets however are icy dirtballs that form in the outer solar system. The icy surface is embedded with dust, grit, and other particles from space. Many comets have elliptical orbits that cut across the orbits of planets, making them come very close to the sun and then swinging them far away. Some of the more distant comets can take more than 30 million years to complete one orbit. Some of the comets with smaller orbital paths can take less than 200 years. When far away from the sun, comets are very cold, icy dirtballs. As they approach the sun their surface begins to warm and volatile minerals begin to vaporize. The vaporizing gases carry small duct grains with them which can result in a bright shining tail trailing behind the comet.