Interstellar Comet 3I/ATLAS Is About To Vanish From View – And Won't Be Back Until Later This Year

Interstellar comet 3I/ATLAS is about to vanish from view. Earth and this interstellar interloper will be on opposite sides of the Sun for a little while. The glare of our star will be blocking the object from view in the coming days, until the two celestial bodies appear too close in the sky for the dim comet to be visible.

The rest of this article is behind a paywall. Please sign in or subscribe to access the full content.

The comet is currently several degrees away from the Sun, setting about an hour after our Sun, making it the "best" time to see it. But you need to have a very good instrument, because the comet is really dim; it's a smallish speck currently around the orbit of Mars. Soon, the apparent distance between comet 3I/ATLAS and the Sun will become smaller and smaller, culminating in their closest distance around late October.

The interstellar comet is not getting anywhere near the Sun, however, at least compared to other comets. Its perihelion, the closest approach to our star, is happening on October 29; at this point, comet 3I/ATLAS will be 202 million kilometers (126 million miles) away from the Sun. This means that Earth’s going to miss the moment when the comet will be at its most active, which is a bit unfortunate.

Comet 3I/ATLAS is very different from the previous two known interstellar comets: 1I/’Oumuamua, discovered in 2017, and Comet 2I/Borisov, discovered in 2019. 3I/ATLAS is moving almost twice as fast as the other two, and it is larger than they are. It is likely to have come from the thick disk of the Milky Way, unlike the other two, which are from the thin disk, the region where we reside. Studying this object is key to better understanding interstellar objects and what other solar systems might be like. The recent change in color is truly intriguing, for example.

The comet will be visible again from late November, before its closest passage to Earth, which will be 268 million kilometers (167 million miles) away. Definitely not a close encounter, but hopefully, we will be getting some more insight into this fascinating object before and after then.