(CNN) — Astronomers using the Hubble Space Telescope detected water molecules in the atmosphere of a small exoplanet 97 light years from Earth.
The planet, called GJ 9827d, is about twice the diameter of Earth and is the smallest exoplanet that has been found to have a water-rich atmosphere, according to a new study.
While water is essential for life as we know it, the scorching temperatures on GJ 9827d are unlikely to support any life, turning a water-rich atmosphere into scorching steam.
The discovery paves the way for new research as astronomers seek to understand the origins of planets beyond our solar system.
The findings of the study, led by principal investigator Ian Crossfield of the University of Kansas, were published Thursday in The Astrophysical Journal Letters.
Laura Kreidberg, head of the department of exoplanet atmospheric physics at the Max Planck Institute for Astronomy in Heidelberg, Germany, and co-author of the study, called the discovery “historic.”
She said, “Water on such a small planet is a historic discovery. It comes closer than ever to characterizing truly Earth-like worlds.”
However, the planet reaches temperatures of 800 degrees Fahrenheit, making it a vaporous, inhospitable world with temperatures as hot as Venus.
Björn Benneke, a professor at the Trottier Institute for Exoplanet Research at the University of Montreal and co-author of the study, said, “This would be the first time we have directly demonstrated through atmospheric detection that these planets with water-rich atmospheres can actually exist around other stars.”
The research team is currently unable to say whether Hubble detected traces of water vapor within a swollen, hydrogen-rich atmosphere or whether the planet has a water-rich atmosphere because the host star evaporated the original hydrogen-helium atmosphere of GJ 9827d.
The planet, initially discovered by NASA’s Kepler mission in 2017, is observed during 11 transits over three years. Starlight filtered through the planet’s atmosphere helped astronomers measure the signature of water molecules.
It’s still unclear what kind of world GJ 9827d is, but two possible theories have been proposed by the research team.
According to the researchers, it’s possible that the planet is a mini-Neptune with a hydrogen-rich atmosphere containing water vapor. Another theory is that GJ 9827d could be a hotter version of Jupiter’s icy moon Europa, which contains an ocean beneath an icy crust.
Water is one of the most common molecules found in the universe, and astronomers have been looking to detect water as an important part of the search for life beyond Earth.
Thomas Greene, an astrophysicist at NASA’s Ames Research Center and co-author of the study, said, “Observing water is looking through a gateway to find other things. This Hubble discovery opens the door to future studies of such planets by the James Webb Space Telescope.”
Astronomers have already observed GJ 9827d with the Webb telescope to look for water and other types of molecules.
“We’re eager to see what that data reveals,” said Kreidberg. “Hopefully, we can now resolve the issue of the water worlds once and for all.”