Hot Jupiters are a class of exoplanets which have a masses roughly the equivalent to Jupiter’s but orbit their stars considerably closer than Jupiter’s orbit of our sun. As a result, these hot Jupiters can reach ridiculous temperatures of 1,100 degrees Celsius (about 2,000 degrees Fahrenheit). Consequently, any surface water is obviously non-existent and is simply water vapor or atmospheric water.

Water Found On Some "Hot Jupiters"

Some atmospheric water on hot Jupiters, many without detectable water

The fact that some hot Jupiters have water and others don’t has baffled scientists since the discovery of said hot Jupiters. In order to solve this mystery, researchers at NASA’s Jet Propulsion Laboratory used the Hubble Space Telescope to have a look.

Using data from the Hubble’s Wide Field Camera 3, the group looked at 19 hot Jupiters that had already been observed  and water was detected on 10 of the 19. When I say previous observation it’s important to note that these observations and accompanying data was gleaned from over nine separate studies and the analysis and interpretation of the data was conducted quite differently in each study so the team was forced to consolidate it before looking for a pattern for comparison. By doing this the researchers were able to put together a standard light spectrum for the 19 hot Jupiters.

This study could either break ground on hot Jupiters or come to absolutely nothing by the team’s own admission. Once the spectrum was put together it was modeled onto planets with no clouds in the atmosphere as well as planets blanketed in numerous levels of clouds of varying thickness.

“Clouds or haze seem to be on almost every planet we studied,” said Aishwarya Iyer, a JPL intern from the California State University, in a statement. “You have to be careful to take clouds or haze into account, or else you could underestimate the amount of water in an exoplanet’s atmosphere by a factor of two.”

As a result, the researchers don’t know that clouds aren’t keeping Hubble from being able to detect water in the atmosphere. It’s also quite possible that there is no water vapor to observe.

“There could still be more water below,” says JPL Intern Aishwarya Iyer of California State University, Northridge.

While the scientists observed clouds on all 19 hot Jupiters studied, but they really don’t know what they are made of but know that temperatures on hot Jupiters means it’s surely not water.

The new study, which is published in the Astrophysical Journal, will be an important part of understanding the formation of exoplanets including these hot ones.