Scientists have been studying the planet Jupiter to determine why the atmosphere over the planet's southern hemisphere contains more water than the atmosphere over the northern hemisphere of planet. The scientists used data collected from the Herschel space observatory to determine that the southern hemisphere of the atmosphere contains more water.
Using the data collected, the scientists have theorized that the source of the increased water in the planet's upper atmosphere has to be from external regions. Specifically, the scientists believe that the extra water in the upper atmosphere was caused by the impact of the Shoemaker-Levy 9 comet with the surface of the planet back in 1994. Considering that comets are made out of ice and rock, a comet impact would certainly have the potential to release large amounts of water into the upper atmosphere of the planet.
Study lead Thibault Cavalie says that the difference in water between the two hemispheres suggests that the extra water in the southern hemisphere was delivered during a single event. That would rule out the water coming from other sources such as icy rings or moons orbiting the planet. Cavalie says that the team's model indicates that as much as 95% of the water in the stratosphere of Jupiter was put there by the impact of the comet in 1994.
The scientists also point out that it's not uncommon for other planets in our solar system to have water in their atmospheres. The odd thing about Jupiter was one hemisphere having more water than the other. The water in the atmosphere also wasn't aligned to the poles of the planet.
Cavalie said, "The asymmetry between the two hemispheres suggests that water was delivered during a single event and rules out icy rings or moons as candidate sources...Local sources would provide a steady supply of water, which over time would lead to a hemispherically symmetric distribution in the stratosphere. Depending on whether the chemical species are transported in neutral or ionized form, local sources of water would result in higher concentrations either at the poles or along the equator, but not in a north-south asymmetry."