defining asteroid, meteor, comet
By: Patience Ervin
A Meteor is a small rocky or metallic body travelling through space. Meteoroids are significantly smaller than asteroids and range in size from small grains to 1 meter-wide objects.Most are fragments from comets or asteroids, while others are collision impact debris ejected from bodies such as the moon or mars.
A comet is an icy small solar system body that, when passing close to the sun heats up and begins to outgas, displaying a visible atmosphere or coma, and sometimes also a tail. These phenomena are due to the effects of solar radiation and the solar wind upon the nucleus of the comet.
Asteroids are minor planets especially those of the inner solar system. The larger ones have also been called planetoids. These terms have historically been applied to any astronomical object orbiting the sun that did not show the disk of a planet and was not observed to have the characteristics of an active comet, but as minor planets in the outer solar system were discovered, their volatile-based surfaces were found to resemble comets more closely and so were often distinguished from traditional asteroids.