Comets

Comets are icy bodies from the Kuiper Belt and Oort Cloud which enter the inner solar system. Comets originating from the Kuiper belt have short orbital periods below 200 years, bodies from the Oort Cloud have orbits ranging from 200 years up to millions of years. When these icy objects enter the inner solar system the effects of solar winds and radiation vaporizes the ice creating a thin atmosphere around them known as a coma, occasionally they will also develop a tail.

It is believed that the gravitational pull of the outer planets bring bodies from the Kuiper Belt into the inner solar system. Objects in the Oort Cloud are effected by giant molecular clouds or passing stars that can nudge them out of their orbit. As comets cross the orbital paths of planets they do occasionally collide with them, as was the case in 1994 when fragments of Comet Shoemaker-Levy 9 hit Jupiter.

Comets are extremely important in the development of planets as they possess vital volatile elements, including most importantly water. In its early life planet Earth was bombarded by comets, creating liquid water oceans on its surface, without this event it is possible that life may not have developed on our planet.

There has already been several stunningly successful missions to study comets, Giotto in 1986 studied Halley’s Comet and then went on to make a close pass of Grigg-Skjellerup in 1992. Stardust captured comet dust from Comet Wild 2 in 2004 and returned those samples safely to Earth. It then went on to make a flyby of comet Tempel 1. In 2005 an even more ambitious mission was launched. Deep Impact was equipped with a probe that would be sent on a collision course with Comet Tempel 1. The probe successfully crashed into the comet in July of that year.

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Comets - Images & Video

Comet Bombardment of Early Earth

Deep Impact Approaching Comet

Hale Bopp from Earth