The Last Sighting of Comet 3I/ATLAS Is Streaming — Here's When to Watch

The solar system is about to bid a permanent goodbye to a rare guest that has journeyed from the deepest reaches of the Milky Way. While the object sparked intense debate regarding its origins last year, it is now on a definitive trajectory out of our neighbourhood.

Stargazers who missed the initial pass have been granted a brief reprieve due to inclement weather, but the window of opportunity is closing rapidly. This week marks the absolute final chance to witness this interstellar traveller before it vanishes into the cosmic void forever.

Postponed Livestream

Poor weather conditions in Italy necessitated a schedule change for the broadcast hosted by the Virtual Telescope Project. Originally slated for an earlier date, the live feed has been moved to Thursday, 22 January.

The event is scheduled to begin at 11:30 p.m. GMT (6:30 p.m. EST). The broadcast, titled 'Farewell, 3I/ATLAS: a final view of this exceptional object', will feature real-time views from the project's robotic telescopes stationed in Manciano, Italy.

On the rescheduled date, Earth will be positioned directly between the sun and the comet. The sun's light will hit the comet directly from our perspective, similar to a full moon. Whilst 3I/ATLAS remains incredibly faint, this direct lighting provides the best possible chance to observe it against the backdrop of space.

Origins of 3I/ATLAS

We haven't known about this object for long, but its backstory is already gripping. A remote telescope in Río Hurtado, Chile, first spotted it on July 1, 2025, during a Deep Random Survey. The project is part of the Asteroid Terrestrial-impact Last Alert System, which is why you see 'ATLAS' in the name.

At first, scientists just tagged it as A11pl3Z. But once they noticed it acting like a comet, they renamed it C/2025 N1 ATLAS. However, once researchers plotted its trajectory, the numbers simply didn't fit the profile of a local object. It was following a 'hyperbolic orbit'—meaning it wasn't locked into a loop around our sun. It was moving too fast for the sun's gravity to hold it back.

That path confirmed the object originated from a different star system and was merely passing through. This earned it the official title 3I/ATLAS, making it only the third interstellar visitor ever observed, following 1I/'Oumuamua in 2017 and 2I/Borisov in 2019.

The Alien Craft Theory

The arrival of 3I/ATLAS prompted speculation about its nature. Harvard astrophysicist Dr Avi Loeb suggested it could be an alien craft rather than a natural object, which generated significant online discussion.

While the idea of alien tech is exciting, it sparked a lot of wild conspiracy theories that drowned out the actual science. Unfortunately for sci-fi fans, the hard evidence we have points strongly to a natural origin.

Information gathered by NASA's Psyche mission and ESA's Mars Trace Gas Orbiter indicates that the object is accelerating in a manner consistent with a comet. This acceleration is caused by 'outgassing', a process where jets of vaporised gas escape the surface and act as tiny thrusters.

This behaviour is standard for comets native to our own solar system and effectively rules out artificial propulsion. The slight push observed by the orbiters confirms that 3I/ATLAS is an icy body reacting to solar heat, rather than a constructed probe.

Technical Challenges in Viewing the Faint Cosmic Visitor

Observing this retreating visitor requires significant equipment. The comet is currently traversing the pre-dawn sky and will remain there until spring in the Northern Hemisphere. However, it is far too faint to be seen with the naked eye or even standard binoculars.

Imaging the object requires at least a large 8-inch digital telescope. For those wishing to view it optically through an eyepiece, a massive 16-inch telescope is necessary to resolve the faint speck of light. This high barrier to entry makes the upcoming livestream essential for most enthusiasts.

This is truly the last call for observation. The object is returning to the interstellar medium from whence it came, likely the centre of the Milky Way. Once it fades from view after this final appearance, 3I/ATLAS will never be seen again.