Comets

They are basically smaller than meteors. Comets are composed of ices, dust and rocky debris carried from the early formation of the solar system about 4.5 billion years ago.Comets are remnants from the cold, outer regions of the solar system. They are generally thought to come from two areas - the Oort Cloud and the Kuiper Belt. Both of these are areas where materials left over from the formation of our solar system have condensed into icy objects. Both regions extend  beyond the orbits of Neptune and Pluto but are still part of our solar system and much closer to us than the closest star. Haley Bopp will return  Comets are composed of ices, dust and rocky debris carried from the early formation of the solar system about 4.5 billion years ago.

Comets are remnants from the cold, outer regions of the solar system. They are generally thought to come from two areas - the Oort Cloud and the Kuiper Belt. Both of these are areas where materials left over from the formation of our solar system have condensed into icy objects. Both regions extend beyond the orbits of Neptune and Pluto but are still part of our solar system and much closer to us than the closest star in 4380.

The most recent comet
Mcnought, appeared September 7, 2006. In 1993 Shoemaker-Levy fragmented and dissolved in Jupiters atmosphere leaving Jupiters "Big Black Eye."

Encke-shortest orbital period 3.3 years around sun. The way this travels is an extremely elongated orbit. This may contain materials ancient to Earth. It even could have delivered water. Oort cloud is yet another group. Most comets generally have heart frozen mass of ice size of mountains. The reason why its tale is icy is because the ice melts and forms glowy tail. NASAs Stardust was the first to visit a  comet and return in 2006.