A few years ago Jupiter was hit by several chunks of the comet Shoemaker-Levy 9 after the comet broke apart. The massive gravity of Jupiter ripped that comet into pieces and those chunks collided with the planet. Since Jupiter has such a thick atmosphere, all we could see were the effects the impact had on the thick atmosphere.
I'm sure I'm not alone in wondering exactly what the impact caused by those comets did to the surface of Jupiter underneath that thick blanket of atmosphere. We may get an idea of exactly how much damage a fast-moving comet can do to the surface of a planet next year. Astronomers say that there is a small chance that Mars could be struck by a comet in 2014.
The interesting part about a potential comet strike on the surface of Mars is that we currently have probes on the ground and satellites in orbit around the planet that could gather an incredible amount of information for scientists. Another interesting fact is that Mars has no thick Jovian atmosphere to soften or obscure the impact.
The comet with a chance of hitting Mars next year is called C/2013 A1 and it was spotted by an Australian Observatory on January 3, 2013. The astronomers do point out that odds are the comet will simply zip by Mars leaving nothing more than a celestial light show for astronomers and scientists to enjoy. The chance of the comet hitting the surface of Mars is small, but scientists describe it as "non-negligible." According to scientists, the odds of an impact with the surface of Mars are 1 in 2000. The comet is believed to be anywhere from 0.6-1.9 miles wide and traveling at about 125,000 mph. If the impact happens, it would deliver as much energy as 35,000,000 megatons of TNT.