In July 1994, the comet Shoemaker-Levy 9 plowed into Jupiter, and the comet fragments triggered dark scars of debris in the giant planet’s atmosphere that were visible for weeks. The comet also left behind a more permanent deposit: millions of gallons of water. Water from the impact still makes up at least 95 percent of the water in the planet’s upper atmosphere, researchers report April 23 in Astronomy & Astrophysics.
Telescopes had previously spotted water in Jupiter’s upper atmosphere, some 100 kilometers above the planet’s ammonia cloud tops, but those surveys could not determine where the water came from. So astronomers used the European Space Agency’s Herschel Space Observatory to create a high-resolution map of water vapor distribution throughout Jupiter’s atmosphere. The researchers, led by Thibault Cavalié at the Laboratory of Astrophysics of Bordeaux in France, found that the concentration of water peaked in the planet’s southern hemisphere, right in the region where the comet struck.
More water also appeared at higher altitudes around the planet, which Cavalié says supports the comet as its origin. Water from other sources such as Jupiter’s icy moons would likely spread out more evenly around the planet and would gradually filter down to lower altitudes.