Comets and Asteroids
By: Cole Johnson
- Where do Comets form ? Well where comets form depends upon the period of their orbit. So comets with shorter orbital periods come from a part of the solar system called the scattered while the comets with longer orbital periods are believed to come from the Oort cloud.
When did comets form ? about 4.6 billion years ago
How do comets form ? They form from the material left over from the formation of the planets.
- In the Solar system, all of the Planets ( Mars, Earth Venus, etc. ) orbit in a counter-clockwise direction while comets orbit in the opposite direction.
- Comets have tails because as they approach perihelion ( place in their orbits when they are closest to the Sun ) the Sun's heat vaporizes some of the comets material, releasing dust particles that were trapped in ice.
- The picture on the upper right of the page is the Hyakutake comet. This picture was taken by the Hubble Space Telescope on April 4, 1996.
- A meteor is a flash of light that we see in the night sky when a chunk of interplanetary debris burns up as it passes through our atmosphere. The debris is called a meteoroid and an asteroid is a small rocky body orbiting the sun.
- A "near-Earth asteroid" is an asteroid that have been nudged by the gravitational attraction of nearby planets into orbits that allow them to enter the Earth's neighborhood.
- About 2 billion years ago the Vredefort Crater which had an estimated radius of 118 miles crashed in Free State, South Africa. This made it the world's largest known impact structure.
-The picture below is the Ida Asteroid, this photo was taken by the imaging system on the Galileo space craft.