How can the easiest gas to escape be the one that hides the longest? On June 1, 2026, NASA shared that the James Webb Space Telescope had directly detected methane on 3I/ATLAS, a comet from outside our solar system. That alone was a first for an interstellar visitor. But the real puzzle was the timing. Methane is very volatile. It usually changes from ice to gas quickly. So why did it show up clearly only after the comet had already swung around the Sun? (science.nasa.gov)

3I/ATLAS is only the third identified interstellar object, and it was first reported on July 1, 2025, by the ATLAS survey in Chile. Webb studied it again in mid-December 2025, when the comet was already heading back out of the solar system. The telescope saw not only methane, but also an unusually large amount of carbon dioxide compared with water. That chemical mix is rare among comets born around our own Sun. So this visitor already seemed different before scientists even tried to explain the methane. (science.nasa.gov)

Here is one simple way to picture it. Imagine a cream bun from a bakery. The outside warms first. The cold filling stays hidden until later. Scientists think something like that may have happened on 3I/ATLAS. The methane was probably buried under the comet’s top layer. It stayed protected until heat from the Sun reached deeper ice after the comet’s close pass. If that idea is right, then the methane is more than a gas. It is a clue. It suggests that 3I/ATLAS formed in a very different chemical setting around another star. Sometimes the universe keeps its biggest secrets under the surface, waiting for just enough warmth to speak. (science.nasa.gov)