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- Jupiter\u2019s moon Europa has a global ocean beneath its icy crust.<\/strong> Does it have water vapor plumes too, like Saturn\u2019s moon Enceladus?<\/li>\n
- Previous observations by the Hubble Space Telescope<\/strong> hinted at plumes, although smaller than those on Enceladu. But the plumes might not be there after all, a new study from SwRI says.<\/li>\n
- Plumes aren\u2019t at all ruled out by the study, though.<\/strong> The data for their existence just isn\u2019t as concrete as before.<\/li>\n<\/ul>\n
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Europa\u2019s water vapor plumes: real or not?<\/h3>\n
Do plumes of water vapor blast from Jupiter\u2019s moon Europa, like they do from Saturn\u2019s moon Enceladus? Scientists have debated this for years. <\/p>\n
Some previous observations by the Hubble Space Telescope hinted these plumes were there, but smaller and more sporadic than the ones on Enceladus. But now, a new study casts doubt the plumes being there at all.<\/p>\n
Researchers from the Southwest Research Institute (SwRI) said on May 18, 2026, that the evidence for the plumes isn\u2019t as strong as it once was.<\/p>\n
The new study examines 14 years of Hubble observations using its Imaging Spectrograph (HST\/STIS). Those observations focused on Europa\u2019s Lyman-alpha emissions, a specific wavelength of ultraviolet light emitted and scattered by hydrogen atoms.<\/p>\n
The researchers published their new peer-reviewed paper in Astronomy & Astrophysics<\/em> on May 5, 2026.<\/p>\n
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SwRI in the news: New data casts doubt on the existence of vapor plumes on Europaow.ly\/IW5750Z2c8Q<\/p>\n
\u2014 Southwest Research Institute (@swri.org) 2026-05-20T18:02:38.988Z<\/p>\n<\/blockquote>\n
Difficulties in interpreting the data<\/h3>\n
There was some difficulty in interpreting the data from the original Hubble observations going back to 2014. It had to do with exactly where Europa was in the images. Co-author Kurt Retherford at SwRI explained:<\/p>\n
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One of the difficulties in interpreting the data back then was determining where to place Europa within its context. The way Hubble works left some uncertainty in terms of placement relative to the center of the image. If Europa\u2019s placement was off even just by a pixel or two, it could affect how the data gets interpreted.<\/p>\n<\/blockquote>\n
![\"A](\"https:\/\/earthsky.org\/upl\/2018\/05\/europa-plumes-galileo-sq-800x800.jpg\")
Previous image from the Hubble Space Telescope, showing possible plumes on Europa\u2019s surface. Video still, via NASA.<\/figcaption><\/figure>\n ![\"Sunlit](\"https:\/\/earthsky.org\/upl\/2024\/04\/Enceladus-plumes-Cassini.jpeg\")
View larger. | Saturn\u2019s moon Enceladus is well-known for its huge geyser-like plumes of water vapor. The plumes originate in the global subsurface ocean and erupt through cracks in the outer ice shell at the moon\u2019s south pole. Image via NASA\/ JPL\/ Space Science Institute.<\/figcaption><\/figure>\n Plumes not ruled out<\/h3>\n
Lead author Lorenz Roth at the KTH Royal Institute of Technology in Sweden added:<\/p>\n
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Our reanalysis took our original 99.9% confidence in the plumes\u2019 existence and reduced it to less than 90% confidence. That\u2019s simply not enough evidence to support the certainty of claims we made at the time.<\/p>\n<\/blockquote>\n
So the previous confidence level has dropped enough that the researchers can\u2019t say for sure the plumes are there. But they are not ruled out, either. It\u2019s just that the evidence isn\u2019t concrete anymore. Retherford said:<\/p>\n
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The description of the phenomena just doesn\u2019t hold up the same way anymore. The new data has made us reconsider the strength of the previous paper\u2019s conclusion regarding water vapor plumes. The recent analysis also provides improved information about the neutral hydrogen atom component of Europa\u2019s escaping atmosphere, originating from its water ice surface.<\/p>\n<\/blockquote>\n
![\"Smiling](\"https:\/\/earthsky.org\/upl\/2026\/05\/Lorenz-Roth-KTH-Royal-Institute-of-Technology.jpeg\")
Lorenz Roth at the KTH Royal Institute of Technology in Sweden is the lead author of the new study about Europa\u2019s plumes. Image via KTH.<\/figcaption><\/figure>\n Europa Clipper<\/h3>\n
We will likely have to wait for NASA\u2019s Europa Clipper to arrive at Europa in April 2030 to know for sure whether Europa has plumes or not. Clipper will make multiple close flybys of Europa, studying its surface and interior in more detail than ever before. It will try to determine if Jupiter\u2019s moon actually is habitable. And it will be able to detect any plumes \u2026 if they are there.<\/p>\n
Bottom line: New observations from the Hubble Space Telescope suggest that Europa\u2019s water vapor plumes are less likely than previously thought. But they don\u2019t rule them out.<\/p>\n
Source: Europa\u2019s Lyman-a emissions from HST\/STIS observations<\/p>\n
Via SwRI<\/p>\n
Read more: Seeking Europa\u2019s water plumes with Clipper<\/p>\n
Read more: Possible water plumes spotted on Europa<\/p>\n
<\/div>\n
\n - Previous observations by the Hubble Space Telescope<\/strong> hinted at plumes, although smaller than those on Enceladu. But the plumes might not be there after all, a new study from SwRI says.<\/li>\n