NASA Webb telescope detects methane on interstellar comet 3I/ATLAS, first on a visitor from another star
NASA's James Webb telescope detected methane on 3I/ATLAS, a comet from another star system, the first time methane has been found on an interstellar visitor. It is releasing far more methane relative to water than comets from our solar system, a sign it formed somewhere very diff
Astronomers have detected methane on a comet that came from another star system, the first time the gas has been found on an interstellar visitor. The discovery comes from NASA's James Webb Space Telescope, which used its mid-infrared instrument to study comet 3I/ATLAS as it swung through the inner solar system and headed back toward deep space in late 2025. Methane is common on comets that formed around our own Sun, but 3I/ATLAS is releasing far more methane relative to water than those local comets typically do. Researchers read that imbalance as a clue about where and how the object formed. Because 3I/ATLAS originated around a different star, its chemistry carries a record of conditions in a planetary system other than ours, something scientists almost never get to measure directly. The team published the findings in The Astrophysical Journal Letters. Only a handful of confirmed interstellar objects have ever passed through our solar system, so each one offers a rare chance to compare the raw material of distant star systems with our own. Source: NASA Science, ScienceDaily, Space.com.