Comet 3I/ATLAS will make its closest approach to Earth on December 19, 2025, and can be watched via the Virtual Telescope Project live stream, scheduled to start at 04:00 UTC on December 19 (23:00 EST on December 18).
Ground-based observations on November 16 and 17, 2025 captured multiple jets on the interstellar object 3I/ATLAS, including sunward jets and an extended anti-tail. The images were obtained from telescopes in New Mexico, USA and France. A public online observation by the Virtual Telescope Project is scheduled at 04:15 UTC on November 19, 2025.
Interstellar object 3I/ATLAS brightened sharply and turned bluer as it passed perihelion on October 29 2025, according to a new preprint by Q. Zhang and K. Dattams and commentary by astrophysicist Avi Loeb.
Interstellar object 3I/ATLAS (C/2025 N1 ATLAS) will reach its perihelion distance of about 1.36 AU from the Sun on October 29, 2025, marking the midpoint of its one-time passage through the Solar System. The hyperbolic object will be unobservable from Earth during the event but will later pass within 97 million km (60 million miles) of Venus and 54 million km (34 million miles) of Jupiter on its way out of the system.
Spectroscopic observations with the Keck II telescope in Hawaii revealed distinct nickel and cyanide emissions surrounding the interstellar object 3I/ATLAS, extending several hundred kilometers from its nucleus. The data, presented by Hoogendam et al. (2025) and summarized by astrophysicist Avi Loeb, show an anomalous concentration of nickel and an absence of iron lines—behavior unseen in known comets. These results, together with earlier Hubble images showing an anti-tail oriented toward the Sun, further reinforce the object’s unusual nature.
The interstellar object 3I/ATLAS showed no measurable non-gravitational acceleration between May and September 2025, implying a nucleus mass above 33 billion tons and a diameter larger than 5 km (3 miles), according to a study co-authored by Harvard Professor Avi Loeb and published on September 24.
A coronal mass ejection (CME) launched from the Sun on September 19 is forecast by NASA’s ENLIL model to strike interstellar Comet 3I/ATLAS on September 24 or 25, an extremely rare event that comes as the comet brightens 40-fold and prepares to disappear into the Sun’s glare.
NASA released the first results of James Webb Space Telescope (JWST) observations of interstellar comet 3I/ATLAS on August 25, 2025, showing a coma dominated by carbon dioxide. The comet was observed on August 6, and complementary data from Hubble and SPHEREx confirm unusual volatile ratios.
Could “comet”3I/ATLAS be a piece of alien technology? A question that might sound straight out of a sci-fi movie is now being brought to the front of the space table by Abraham (Avi) Loeb the Baird Professor of Science and Institute director at Harvard University.
Interstellar comet 3I/ATLAS, first observed by the ATLAS survey in Chile on July 1, 2025, is the third confirmed object of its kind to enter the solar system. Analysis of its hyperbolic trajectory and inbound velocity of ~58 km/s confirms its extrasolar origin, while kinematic modeling suggests it formed in the Milky Way’s ancient thick disk, offering a rare opportunity to study early galactic comet chemistry.
