Recent studies of the interstellar comet 3I/ATLAS have revealed that it contains an unusually high ratio of methanol to hydrogen cyanide compared to other comets.

Most known comets formed in the early Solar System. In contrast, comet 3I/ATLAS originated in another planetary system and later entered the Solar System, which classifies it as interstellar. As it approaches the Sun, the comet’s icy surface heats up, causing the ice to turn into gas and escape into space, forming a glowing cloud known as a coma.

Observations of the comet were conducted using the ALMA radio telescope array. During the research, scientists recorded the spectral signatures of molecules at specific wavelengths, allowing them to identify the comet’s chemical composition. Measurements showed the presence of methanol and hydrogen cyanide—molecules commonly found in comets. However, in 3I/ATLAS, the methanol-to-hydrogen cyanide ratio was found to be 70 to 120 times higher than in other comets, making it one of the richest methanol sources among studied objects. This chemical makeup suggests the comet formed under conditions different from those in the Solar System.

ALMA’s research also made it possible to study how different gases escape from the comet. Hydrogen cyanide is released directly from the nucleus, while methanol comes both from the nucleus and from tiny icy grains in the coma that act like mini-comets. Solid methanol sublimates into gas, releasing additional molecules in a process known as extended outgassing. These findings have contributed to a deeper understanding of the chemistry of other planetary systems and how they compare to our Solar System.