Trending Now - Doubts Arise Over Water Vapor Claims on Europa's Surface

WHO:

Space.com - Researchers from the Southwest Research Institute, including Lorenz Roth and Kurt Retherford.

Gizmodo - The team includes many members from the 2014 study.

WHAT:

Space.com - The evidence for water vapor plumes on Europa is now considered less strong than previously understood.

Gizmodo - The 2014 paper claimed a 99.9% confidence in the existence of water vapor plumes, which has now been reduced to "less than 90%."

Gizmodo - The latest analysis published in Astronomy & Astrophysics questions the certainty of the 2014 results, suggesting that previous evidence may have been statistical noise.

WHERE:

Gizmodo - The observations were made on Europa, one of Jupiter’s moons.

WHEN:

Gizmodo - The original Hubble data was collected between 1999 and 2020.

Gizmodo - The initial findings regarding water vapor plumes were published in a 2014 Science paper.

WHY:

Gizmodo - The discrepancy in results arises from differences in the assumed position of Europa’s disk on the detector.

Gizmodo - The researchers aimed to better understand the hydrogen content in Europa’s exosphere and revisit the water plumes hypothesis.

HOW:

Gizmodo - The team reviewed Hubble data and took steps to address past issues, including observing Europa in sunlight and when it wasn’t transiting Jupiter.

Gizmodo - The researchers studied Lyman-α and OI emissions detected by Hubble, which are signatures of hydrogen and oxygen.

(UPDATED May 22, 2026 13:50 UTC)

Researchers from the Southwest Research Institute have found that the evidence for water vapor plumes on Europa, one of Jupiter’s moons, is now considered less strong than previously thought. A recent analysis published in Astronomy & Astrophysics has reduced the confidence in the existence of these plumes from 99.9% to less than 90%, suggesting that earlier findings may have been statistical noise. The team revisited Hubble data and made new observations to better understand the hydrogen content in Europa’s exosphere and to clarify the water plumes hypothesis.