A tale of the two Atlas objects: one is a comet that scientists have determined recently split into 3 core pieces while the other is an unknown object that some scientists believe is an alien spacecraft racing through the Solar System. Both are being monitored by scientists around the Earth. Because both were discovered by the same system and feature the word “Atlas”, some are confusing the two objects or thinking news about one is news about the other.

C/2025 K1 (Atlas) was discovered by Asteroid Terrestrial-impact Last Alert System (ATLAS) in May; it is an Oort cloud comet and can be viewed with large binoculars on Earth. As of the start of November 2025, the comet can be seen just before sunrise, with a tail that has a distinctly golden color.

Over November 11-12, astronomers using the 1.82 m Copernicus telescope at the Asiago Observatory in Italy were able to observe a fragmentation of its ancient nucleus. The nucleus of a comet is its solid, frozen core, made of a mixture of ice, dust, and rocky particles, often referred to as a “dirty snowball”. The ice is primarily frozen water, but also includes other frozen gases like carbon dioxide, carbon monoxide, and ammonia. This composition gives the nucleus its dark, rocky, and icy surface. It appears when the comet made its closest approach to the Sun on October 8, the structural integrity of the nucleus became compromised, leading to its break-up. Scientists believe there are now three core pieces of the comet, which continue to travel through our Solar System.

While C/2025 K1 (Atlas) is behaving like a comet, the object known as 3I/Atlas isn’t. Thi object was discovered on July 1, 2025 by the NASA-funded ATLAS survey telescope at Río Hurtado, Chile. This newly discovered object was entering the inner Solar System at a speed of 140,000 mph relative to the Sun and was located 325 million miles from Earth. It was initially moving in the sky along the border of the constellations Serpens Cauda and Sagittarius, near the galactic plane. These initial observations initially suggested that the object could be on a highly eccentric path that might come close to Earth’s orbit, which led the International Astronomical Union Minor Planet Center to list the object on the Near-Earth Object Confirmation Page until the orbit could be confirmed. Because it is the third confirmed interstellar object passing through the Solar System, it was given the prefix “3 I” after 2I, known as Borisov, and 1I known as ‘Oumaumua.

However, the interstellar object is not behaving like a typical comet. The object had an unexplained increase in speed after passing close to the Sun. And unlike normal comets, 3I/ATLAS shows no visible gas or dust emissions that could explain its acceleration. If anything, it is exhibiting unusual jets both towards and away from the Sun which also defies expectations of a comet.

One scientists that has been very vocal about this interstellar object is Avi Loeb; he believes it may be an alien spacecraft. Avi Loeb is the head of the Galileo Project, founding director of Harvard University’s  Black Hole Initiative, director of the Institute for Theory and Computation at the Harvard-Smithsonian Center for Astrophysics, and the former chair of the astronomy department at Harvard University (2011–2020). He is a former member of the President’s Council of Advisors on Science and Technology and a former chair of the Board on Physics and Astronomy of the National Academies. He is the bestselling author of “Extraterrestrial: The First Sign of Intelligent Life Beyond Earth” and a co-author of the textbook “Life in the Cosmos”, both published in 2021. The paperback edition of his new book, titled “Interstellar”, was published in August 2024.

The famous astrophysicist continues to publish on his blog on Medium his thoughts on this new object, including things that suggest it’s more of a manufactured object than a natural comet. His posts on Medium can be found here: https://avi-loeb.medium.com/

While C/2025 K1 (Atlas) broke up, 3I/Atlas is still whole. Data and images taken since the object’s closest approach to the Sun still show it is whole. But the images also show plenty of oddities that Loeb continues to write about:

“Given the large-scale jets reported recently, the fact that 3I/ATLAS remains a single body is surprising for a natural comet. In particular, the large-scale image of 3I/ATLAS reported here on November 9, 2025 shows jets reaching out to ~1 million kilometers towards the Sun and ~3 million kilometers in the opposite direction, as discussed here. For a natural comet, the outflow velocity of the jets is expected to be 0.4 kilometers per second, of order the sound speed of gas at the distance of 3I/ATLAS from the Sun. At that speed, the jets must have persisted over a timescale of 1–3 months,” writes Loeb. He also adds later in his entry, “Technological thrusters which point their exhaust towards the Sun would accelerate away from the Sun. This post-perihelion maneuver might be employed by a spacecraft that aims to gain speed rather than slow down through the gravitational assist from the Sun.”

Scientists, including Loeb, are awaiting new imagery and data to learn more about this interstellar object and determine what exactly it is.

Time if of the essence: the object is approaching Earth and will be at its closest point to the planet in just over a month from now on December 19, 2025.