Comet impact. Artwork of comet fragments impacting the night-side of a ringed gas giant (upper left). Comets are icy bodies that trace elongated orbits around the Sun, periodically passing through the ecliptic plane of the planets. They originate from the outer reaches of the solar system. Near the Sun their ice and dust boil and vaporize, forming tails that point away from the Sun. The large gravity of the gas giants (like Jupiter and Saturn) can attract and break up these comets. This helps to protect the inner solar system from potentially devastating impacts. This type of event was observed in July 1994 when fragments of the Shoemaker-Levy 9 comet impacted Jupiter.