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- Comet 3I\/ATLAS<\/strong> is the 3rd known interstellar object to enter our solar system. We are still learning about its composition.<\/li>\n
- New analysis of data<\/strong> from the James Webb Space Telescope reveals that it contains abundant methane.<\/li>\n
- It\u2019s the first time that methane<\/strong> has been found on an interstellar object. The findings suggest that the environment the comet formed in was quite different from that of our solar system.<\/li>\n<\/ul>\n
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Surprise! Comet 3I\/ATLAS has methane<\/h3>\n
NASA\u2019s James Webb Space Telescope has made another significant discovery about the interstellar comet 3I\/ATLAS: it contains methane.<\/p>\n
Researchers said on June 1, 2026, that this is the 1st time scientists have detected methane on an interstellar object. And the finding suggests 3I\/ATLAS was born in a very different environment from that of our solar system.<\/p>\n
The team of researchers made the discovery after using the Webb space telescope to observe the comet as it headed back out of the solar system in December 2025. The fact that methane wasn\u2019t detected as the comet sped into the solar system suggests the gas was buried below the top surface of ice. So it was only detectable when the ice and frozen methane sublimated \u2013 turned directly to gas \u2013 as the comet came close to the sun.<\/p>\n
The researchers published their new peer-reviewed findings in The Astrophysical Journal Letters<\/em> on April 8, 2026.<\/p>\n
1st detection of methane on an interstellar object hints at comet\u2019s origin<\/h3>\n
So this is the 1st time that scientists have found methane on an interstellar object. Mind you, 3I\/ATLAS is only the 3rd of these objects we\u2019ve identified. The 1st discovery was the enigmatic comet \u2018Oumuamua, and the 2nd was the comet 2I\/Borisov.<\/p>\n
The researchers also found that Comet 3I\/ATLAS is oddly rich in carbon dioxide. And this abundance of carbon dioxide and methane provides clues to the comet\u2019s origin. <\/p>\n
Comets in our solar system don\u2019t contain large amounts of these gases. This means that 3I\/ATLAS must have been born in a very different environment and chemistry than that of our solar system. <\/p>\n
![\"2](\"https:\/\/earthsky.org\/upl\/2026\/06\/gases-on-3I-ATLAS-chart-NASA-June-1-2026-e1781019087390.png\")
View larger. | Chart depicting the various gases that Webb found on Comet 3I\/ATLAS. Methane and carbon dioxide are the most common, concentrated near the comet\u2019s nucleus. Image via NASA\/ ESA\/ CSA\/ STScI\/ M. Belyakov (Caltech)\/ I. Wong (STScI), Image Processing: A. Pagan (STScI).<\/figcaption><\/figure>\n Why the delay in detecting the methane?<\/h3>\n
Scientists first spotted Comet 3I\/ATLAS in July, 2025, and it passed closest to the sun in October. But they didn\u2019t detect the methane until the comet was on its way out of the solar system in December. Why is that? <\/p>\n
The researchers say it\u2019s likely because the methane was buried under a significant amount of surface ice. It wasn\u2019t until the comet swung closest to the sun during its departure that the comet warmed enough for the methane to sublimate. Sublimation is when a frozen substance turns directly into a gas instead of becoming liquid first.<\/p>\n
![\"A](\"https:\/\/earthsky.org\/upl\/2026\/04\/Comet-3I-ATLAS-Juice-JANUS-ESA-colours.webp\")
Comet 3I\/ATLAS through red and violet filters. In the red filter, the bright center of the coma is more compact and there are two tails: one straight down, and a fuzzier one going to the lower left. In the violet filter, the coma is bigger but fainter, and only one tail stands out clearly. The differences arise because different gas and dust particles release or reflect light at different wavelengths. Image via ESA.<\/figcaption><\/figure>\n Other recent 3I\/ATLAS news<\/h3>\n
SETI also recently scanned 3I\/ATLAS for possible radio signals. It was a last chance to see if \u2013 by any chance \u2013 the comet might actually be an artificial object. But alas, nothing was found.<\/p>\n
Another study from April found that Comet 3I\/ATLAS formed in a cold environment. This is consistent with the newest findings.<\/p>\n
And in March, scientists found that 3I\/ATLAS is bursting with alcohol, or methanol to be specific.<\/p>\n
Bottom line: New analysis of data from the Webb space telescope shows that Comet 3I\/ATLAS has methane. This shows its origin is different from comets in our solar system.<\/p>\n
Source: The Volatile Inventory of 3I\/ATLAS as Seen with JWST\/MIRI<\/p>\n
Via NASA<\/p>\n
Read more: Interstellar comet 3I\/ATLAS born in a cold environment<\/p>\n
Read more: Interstellar object Comet 3I\/ATLAS leaving the solar system<\/p>\n
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\n - New analysis of data<\/strong> from the James Webb Space Telescope reveals that it contains abundant methane.<\/li>\n