Comet Shoemaker-Levy 9

Hubble Telescope Image of the Comet Shoemaker-Levy 9 before collision with Jupiter

Image Credit:

H.A. Weaver, T. E. Smith (Space Telescope Science Institute), and NASA

 

In 1993, Comet Shoemaker-Levy 9 was discovered by Eugene and Caroline Shoemaker and David Levy in photographs taken of Jupiter. Sometime before its discovery, it passed within the Roche limit of Jupiter and ripped apart by tidal forces from Jupiter's gravity and broke up into 23 individual pieces.

 

Because of its discovery and by following the trajectories of the pieces, the orbits of the pieces could be calculated accurately. From observations, it was determined that the comet would impact Jupiter in July of 1994. This was the first impact that could be accurately predicted and be observed safely as it occured on another planet. The impact of Comet Shoemaker-Levy 9 was going to televised worldwide as this was before the invention of the internet.

 

Over the course of six days, the 23 different pieces of the comet fell on Jupiter. Unfortunately, the impact sites were on the side of Jupiter away from Earth, but luckily on the side that was rotating towards Earth. We might not have seen the impacts directly, but we could see the aftermath on the surface of Jupiter as well as plumes that could be seen over the horizon, if the pieces were large enough.

 

Galileo images of the impact sites

Dept of Physics and Astronomy, University of Tennessee at Knoxville

 

Image of Jupiter with 21 of the fragments

Image Credit:

NASA

MIRAC2 103 micron (one-millionth of a meter) Image of one of the impact

Image Credit:

MIRAC2/NASA/Harvard

 

Watching a comet fall onto Jupiter told us a lot about impacts in the Earth's distant past. It also helped us learn more about Jupiter's atmosphere, which will be addressed in the next post. Early in our history, Earth was continuously bombarded by asteroids and comets, which helped build our planet. In fact, it is believed that the majority of the water on our surface came from the impact of comets with Earth. However, we are not prone to impacts today because there are less asteroids and comets and because Jupiter captures many with its immense gravity. If there was no Jupiter and no large planets, we would be more likely to be impacted by comets and asteroids. If Comet Shoemaker-Levy 9 had hit us, life today might not exist, or at least the kind of life we live today. We should be thankful for Jupiter to vacuum up the majority of the small bodies wandering our Solar System, protecting our planet from catastrophe.