Free Astronomy Magazine May-June 2026

32 ASTRO PUBLISHING Using ALMA’s Morita Array (Ata- cama Compact Array - ACA) in Chile, the research team observed 3I/- ATLAS on multiple dates in late 2025 as the comet approached the Sun. As sunlight warmed its icy surface, the comet released gas and dust, forming a glowing halo—known as a coma—around its nucleus. By ana- lyzing the composition of this coma, astronomers were able to identify the chemical fingerprints of the ma- terial making up the comet and gain insights into the conditions under which it formed. The team focused on the faint sub- millimeter signatures of two mole- cules: methanol (CH ₃ OH), an alco- hol, and hydrogen cyanide (HCN), a nitrogen-bearing organic molecule commonly observed in comets. The ALMA data reveal that 3I/ATLAS is MAY-JUNE 2026 A stronomers using the Ata- cama Large Millimeter/sub- millimeter Array (ALMA) have detected an unusually large amount of the organic molecule methanol in the interstellar comet 3I/ATLAS, revealing chemical condi- tions unlike those found in most comets of our own Solar System. The observations show that 3I/ATLAS contains significantly more meth- anol than hydrogen cyanide, unlike nearly all previously studied comets. These findings provide a rare oppor- tunity to study the chemistry of planetary systems beyond our own. “Observing 3I/ATLAS is like taking a fingerprint from another solar sys- tem,” shares Nathan Roth, lead au- thor on this research and a professor with American University. “The de- tails reveal what it’s made of, and it’s bursting with methanol in a way we just don’t usually see in comets in our own solar system.” ALMA detects extremely abundant alcohol in 3I /ATLAS by ALMA Observatory Nicolás Lira, Jill Malusky, Bárbara Ferreira, Yuichi Matsuda