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Expert: Interstellar comet 3I/ATLAS

A blurry, blueish comet with a fuzzy tail against a black background.
Image by NASA, ESA, David Jewitt (UCLA); Image Processing: Joseph DePasquale (STScI).
Published: 11 September 2025

Four major space telescopes have confirmed unusual findings about a rare interstellar comet, 3I/ATLAS.

Astronomers using the Hubble, SPHEREx, James Webb and TESS telescopes report that the comet鈥檚 early activity and surprising chemical makeup suggest it may have formed in a planetary system very different from our own. Some researchers believe that interstellar objects like 3I/ATLAS could even play a role in planet formation when captured by young star systems.

The comet is the oldest ever recorded and one of only three known to have originated beyond our solar system.

A 黑料不打烊 expert is available to comment on this topic:

Richard L茅veill茅 is an adjunct professor in the Department of Earth and Planetary Sciences and a NASA Participating Scientist with the Mars Curiosity Rover project. He can explain what sets 3I/ATLAS apart from other comets and discuss what these findings reveal about interstellar objects and how planetary systems form.

richard.leveille [at] mcgill.ca (English, French)

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