Using Hubble and Spitzer space telescopes, scientists have found the "fingerprints" of water in the atmosphere of a hot, bloated exoplanet located about 700 light-years from Earth.
Although the researchers predicted they would see water, they were surprised by how much they found.
In fact, the planet, designated WASP-39b, is about the same mass as Saturn, but has three times as much water, according to the U.S. National Aeronautics and Space Administration (NASA).
Though no planet like this resides in the solar system, WASP-39b can provide new insights into how and where planets form around a star, say researchers.
"We need to look outward so we can understand our own solar system," lead investigator Hannah Wakeford was quoted as saying in a statement on Hubble's website recently.
"But exoplanets are showing us that planet formation is more complicated and more confusing than we thought it was. And that's fantastic!" said the researcher of the Space Telescope Science Institute in Baltimore.
Located in the constellation Virgo, WASP-39b whips around a quiet, Sun-like star, called WASP-39, once every four days. The exoplanet is currently positioned more than 20 times closer to its star than Earth is to the Sun.
It is tidally locked, meaning it always shows the same face to its star, according to NASA.
By dissecting starlight filtering through the planet's atmosphere into its component colors, the research team found clear evidence for a large amount of water vapor.
Using Hubble and Spitzer, the team has captured the most complete spectrum of an exoplanet's atmosphere possible with present-day technology.
"This spectrum is thus far the most beautiful example we have of what a clear exoplanet atmosphere looks like," said Wakeford.
Next, researchers hope to use NASA's James Webb Space Telescope, scheduled to launch in 2019, to get an even more complete spectrum of the exoplanet.