The interstellar comet 31/ATLAS has already rewritten scientific expectations, but a rapidly growing catalog of anomalies is now pushing researchers into uncomfortable territory. As the object slices through the inner Solar System, its strange chemistry, geometry, and emissions are forcing astronomers to revisit long-standing comet models—while the public debates whether 31/ATLAS is simply an exotic natural visitor or something far more unusual.
Scientists emphasize that 31/ATLAS is best understood as a stress test for modern astronomy. Each new irregularity—from unusual X-rays to a so-called “heartbeat” signal—adds to a messy and contested dataset that resists clean interpretation.
What Makes 31/ATLAS Fundamentally Different
The most obvious distinction is origin. 31/ATLAS is only the third confirmed interstellar object ever detected passing through our Solar System, following 1I/ʻOumuamua and 2I/Borisov. Unlike those earlier visitors, however, 31/ATLAS is much larger. Detailed measurements place its nucleus at roughly 5.6 kilometers (3.5 miles) in diameter, making it a far more substantial and observable target.
That scale matters. A larger nucleus produces a brighter coma and persists longer under solar heating, giving scientists time to study how truly alien material behaves when exposed to our Sun. According to spectral observations, the Sun is driving the comet’s activity, sublimating its ice into gas and producing a coma rich in carbon dioxide, carbon monoxide, and carbonyl sulfide—chemistry that is familiar but contextually strange given its interstellar origin.
