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.
High-resolution observations from the Virtual Telescope Project on November 13, 2025, revealed multiple fragments and debris structures in the inner coma of comet C/2025 K1 (ATLAS), confirming a post-perihelion breakup.
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.
Comet C/2025 A6 (Lemmon) will make its closest approach to Earth at a distance of 0.596 AU (about 89 million km / 55 million miles) on October 21, 2025, before reaching perihelion on November 8 at 0.529 AU (79 million km) from the Sun.
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.
A newly discovered comet, designated SWAN25B, emerged from behind the Sun in early September 2025 and was added to the Minor Planet Center’s Possible Comet Confirmation Page on September 12. The object is currently reported at magnitude 8.3 in MPC data, with independent amateur estimates placing it slightly brighter at magnitude 7.4–7.5. Orbit calculations are still in progress.
Asteroid 2024 YR4 has a 4 % chance of striking the Moon on December 22, 2032, potentially ejecting up to 100 million kg of lunar debris into space, with as much as 10 % of it reaching Earth and producing a rare, slow-moving meteor storm.
