The most tantalizing feature of the interstellar object 3I/ATLAS, was displayed in an image taken by the Hubble Space Telescope on July 21, 2025. The image showed an extended glow pointed towards the Sun.
The researchers report that the comet shows an “extremely deep and narrow negative polarisation branch,” a phenomenon that sets it apart from every known interstellar or Solar System comet.
Using the Ultraviolet/Optical Telescope aboard NASA’s Neil Gehrels Swift Observatory, astronomers have detected hydroxyl (OH) gas — a chemical fingerprint of water — from the interstellar object 3I/ATLAS.
The comet is unique - not only was it made of carbon dioxide, but it had a carbon dioxide ice-to-water ice ratio that was literally out of this world, 8:1, which is among the highest ever recorded.
The speed and trajectory of 3I/ATLAS suggest that it comes from the thick disk of the Milky Way, the puffy region around the thin disk wherein just 15 percent of the galaxy's stellar mass resides.
Astronomers on Wednesday confirmed the discovery of an interstellar object racing through our solar system - only the third ever spotted, though scientists suspect many more may slip past unnoticed.
