3I/ATLAS Coma Expanding? New Images Reveal Unusual Features of Interstellar Comet
Interstellar comet 3I/ATLAS has been discovered to have an expanding, tail-less coma consisting of micro-jets and unique activity patterns, as new images reveal. Find out how this interstellar visitor is different from ordinary comets.
image for illustrative purpose
Astronomers are rigorously observing 3I/ATLAS, the newly found interstellar comet, because new pictures show strange activity in its coma. Unlike normal Solar System comets, 3I/ATLAS has a symmetric, tail-less coma, smooth gradients, and faint micro-jets, which is why the astrophysics community is so excited.
Photographed by Chuck's Astrophotography on December 2, the raw frames reveal a thicker and more isotropic coma, along with faint activity spikes associated with the rotation of the nucleus. Long-exposure images bring out micro-jets that are directed toward the particular locations, indicating a slow but certain expansion as the comet is receding from the Sun. In contrast to other comets, the solar wind does not affect the shape of its coma, hence producing a smooth glow all over the thing.
3I/ATLAS is the third interstellar object known to us, after ʻOumuamua and Borisov, and it has the Sun's relative speed of 60 km/s on a hyperbolic path. It reached perihelion on October 29, 2025, and is moving outward, gradually exiting the Solar System. It is now about 2.4 AU from the Earth and 2.9 AU from the Sun.
The comet 3I/ATLAS is a subject of study for scientists who want to know the evolution of a dust coma, the patterns of activities, and the behavior of interstellar comets under solar heating. They notice the comet intensity varies mildly but it has not been broken apart or had any other dramatic event. Each set of images gives us deeper knowledge into the interactions of high-speed, low-gravity objects with the environment of the Solar System.
The whole situation points out the rare and exotic traits of interstellar visitors and it is anexceptional chance to get a glimpse into their composition, activity, and structural evolution. While the research goes on, astronomers are hopeful to have 3I/ATLAS comparable with past interstellar objects in order to reveal the patterns and increase our knowledge of these cosmic travelers.
