Green Comet Lemmon Nears Earth, Best Seen in NW Sky After Sunset

Comet C/2025 A6 Lemmon, a green-hued visitor from the outer Solar System, made its closest approach to Earth on October 21 and has been visible across northern latitudes, with amateur photographers in Wales and Scotland among those capturing images of the spectacle. Observers say the comet has brightened rapidly in recent weeks and is best seen low in the northwestern sky after sunset, where it can be picked up in binoculars and, from very dark locations, may be visible to the naked eye.

The object was discovered in January by the Mount Lemmon Survey in Arizona and ordinarily spends most of its time far beyond Neptune. Astronomers estimate the comet last came this close roughly 1,300 years ago, and it will not return to the inner Solar System for many centuries. Its elongated orbit has carried it inward toward the Sun, where solar heating has driven ices on the nucleus to sublimate, releasing gas and dust that form the glowing coma and tails visible from Earth.

Skywatchers report that Lemmon brightened faster than initially expected, reaching an apparent magnitude near 4.8 by mid-October, a level that makes it accessible to observers with binoculars and to unaided eyes under...