3I/ATLAS will align with Earth and Sun on January 22, enabling rare observations of its dust, anti-tail, and composition.
The interstellar object 3I/ATLAS will come very closely aligned with the Sun-Earth axis on January 22, allowing scientists to use the event as an occasion to investigate the object, which is currently beyond our solar system.
On January 22, 3I/ATLAS will be nearly on the same line connecting the Sun and Earth, at only 0.69 degrees. This very specific location gives Earth the position nearly directly separating the Sun and the object, therefore making it possible to see a phenomenon called opposition surge, where the light getting bounced off the dust looks very bright.
The dominant interpretation of this brightness flare involves the pixels of dust hiding their own shadows when light comes directly from the observer's viewpoint. Moreover, light waves bouncing off dust particles may interfere positively and cause an increase in brightness. This becomes helpful for scientists when it comes to their studies of the object's surface composition and dust structure.
One of the most confounding characteristics of 3I/ATLAS is its long anti-tail, which reaches hundreds of thousands of kilometres towards the Sun, contrary to standard comet behavior. The supernova also appears to have three mini-jets that are equally spaced, none of them directed away from the Sun. During the alignment, the anti-tail will almost be pointing towards Earth, making it easier to study it than ever before.
3I/ATLAS, which was found on July 1, 2025, is the third interstellar object ever discovered, after ‘Oumuamua and 2I/Borisov. Different from its predecessor, it has a lot of dust, which makes it scientifically important. Researchers think it could be a billion years old, presenting rare evidence of material formed far beyond the solar system.
Interstellar visitors are extremely rare, and such precise alignment is even rarer. For astronomers, January 22 opens a brief window into an unknown cosmic past, one that may reshape our understanding of interstellar matter and cometary physics.
