The Tail You Didn’t Expect
Typical comets have two tails: a curved dust tail and a straight ion/plasma tail that points away from the Sun. In contrast, 3I/ATLAS shows signs of an anti-tail — a dust/plume structure pointing toward the Sun — and other odd behaviors. Medium
One recent commentary states: “the tail of this comet … is preferentially going in the direction of the Sun.” Planetary Society
There is also evidence of unusual chemical composition: unusually high nickel and carbon-dioxide content, heavier dust particles, and water emissions farther from the Sun than expected.
In short: 3I/ATLAS isn’t behaving like a typical comet from our solar system, making it all the more scientifically tantalizing.
The Spacecraft Opportunity
Here’s where it gets exciting. Two spacecraft – one by NASA, one by ESA – are in positions so that they might pass through or near this object’s tail/anti-tail zone in the coming weeks:
- Europa Clipper: A mission en route to Jupiter’s icy moon Europa, but equipped with instruments thatcouldsample the tail of 3I/ATLAS if conditions align. According to researchers, between October 30 and November 6, Europa Clipper “has a rare opportunity to sample an interstellar object’s tail.”
- Hera: The European Space Agency’s mission to the Didymos–Dimorphos binary asteroid. It too might traverse the tail region during a similar period (late October to early November).
Should either spacecraft succeed, scientists could gain direct physical data from an interstellar cometary tail—a first.
