Growing Tail of Interstellar Comet 3I/ATLAS | Gemini South Telescope

Growing Tail of Interstellar Comet 3I/ATLAS | Gemini South Telescope

A deep image of interstellar Comet 3I/ATLAS captured by the Gemini Multi-Object Spectrograph (GMOS) on Gemini South at Cerro Pachón in Chile, one half of the International Gemini Observatory, partly funded by the U.S. National Science Foundation (NSF) and operated by NSF NOIRLab. The image shows the comet’s broad coma—a cloud of gas and dust that forms around the comet’s icy nucleus as it gets closer to the Sun—and a tail spanning about 1/120th of a degree in the sky (where one degree is about the width of a pinky finger on an outstretched arm) and pointing away from the Sun. 3I/ATLAS is only the third confirmed interstellar visitor to our Solar System.

The exposures tracked the comet as it traveled across the sky, and the final image is composed to freeze the stars in place during the observation. Two small colored trails from unrelated asteroids with motion distinct from that of the comet can also be seen.

These observations of Comet 3I/ATLAS were conducted during a Shadow the Scientists program hosted by NSF NOIRLab. A full recording of the session can be found here.

Gemini South Telescope:
https://noirlab.edu/public/programs/gemini-observatory/gemini-south/

Credit: International Gemini Observatory/NOIRLab/NSF/AURA/Shadow the Scientist
Image Processing: J. Miller & M. Rodriguez (International Gemini Observatory/NSF NOIRLab), T.A. Rector (University of Alaska Anchorage/NSF NOIRLab), M. Zamani (NSF NOIRLab)
Release Date: Sept. 4, 2025

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