ESO’s Very Large Telescope Tracks the Journey of Interstellar Comet 3I/ATLAS [VIDEO]

Interstellar comet 3I/ATLAS was discovered on 1 July 2025 by the ATLAS survey and imaged two days later by ESO’s Very Large Telescope in Chile. It is only the third confirmed interstellar object to visit our Solar System, giving astronomers a short window to study material formed around another star.

A Visitor from Beyond the Solar System

Unlike most comets that formed within the Solar System and return on periodic orbits, 3I/ATLAS originates from deep space and is passing through the Solar System only once. The discovery adds to a short list of interstellar visitors, after 1I/ʻOumuamua in 2017 and 2I/Borisov in 2019.

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Very Large Telescope Records Its Motion

On the night of 3 July 2025, astronomers used the VLT’s FORS2 instrument to capture a sequence of images over about 13 minutes under the dark skies of the Atacama Desert. The frames were later stacked to create a deep composite that highlights the comet’s direction of travel. At the time, this was the clearest view available, and the data are now accessible through the ESO archive. A short timelapse from the same observations shows the comet crossing the star field.

Since then, major facilities have joined the campaign. Hubble imaged the comet in late July, JWST followed in early August. Also, NASA’s SPHEREx mission captured spectra later that month. Early analyses point to a coma rich in carbon dioxide, alongside detections of water ice and other volatiles.

What Happens Next

3I/ATLAS will reach its closest approach to the Sun around 30 October 2025. From Earth, the comet will be lost in solar glare near that time and will not be observable. It is expected to reappear in early December 2025 as it moves away from the Sun, with a close approach to Earth likely in mid-to-late December. The comet poses no threat to our planet.