How to See Comet Lemmon This October

It was early January 2025 when a faint gentle spot was noticed on the Mt. Lemmon Observatory in Arizona. Follow-up observations revealed that the article was a comet visiting from the outer fringe of the photo voltaic system, and it was named Comet Lemmon (C/2025 A6). Its “period”—the time it takes to finish its prolonged orbit of the solar—is about 1,350 years.

At first, the comet was so faint that it may solely be seen with specialised tools. But it has brightened quickly because the months have handed, and by the point fall arrived, it was vivid sufficient to be considered with binoculars. It will now get brighter nonetheless, because it will get nearer to each the Earth and the solar, and will even grow to be seen with the bare eye.

According to NASA, Comet Lemmon can be closest to Earth around October 21, 2025, passing at a distance of about 0.60 astronomical items, or au (1 au is the space between Earth and the solar). The comet is then predicted to succeed in perihelion—the purpose at which it’s closest to the solar—on November 8. Around the time the comet reaches perihelion, it can doubtless attain its most brightness, and could also be seen to the bare eye if circumstances are favorable in darkish skies.

The comet’s tail may even be at its longest extension across the level of perihelion. Tails kind on comets when photo voltaic radiation heats up frozen ice and gases contained within the comet’s nucleus, inflicting them to sublimate—remodel from stable right into a gasoline—with the radiation then inflicting a few of that materials to be emitted out from the comet in a telltale streak. The stronger the radiation, the higher the dimensions of this impact, and so comets’ tails develop as they get nearer to stars and shrink once more after they transfer away.

Comet Lemmon is notable for its greenish tint. This is brought on by the gasoline cloud that surrounds the comet’s nucleus, referred to as its “coma,” with the colour being created by diatomic carbon (molecules of two carbon atoms) interacting with daylight.

Comet Lemmon (C/2025 A6) photographed in Slovenia in early October.

Photograph: Uroš Fink

How to View the Comet

As of early October, Comet Lemmon could be discovered barely beneath the deal with within the Big Dipper (or the Plough, because it’s identified within the UK), which types a part of the Ursa Major constellation. If you lookup on the northern sky, it is possible for you to to hint its path. In the northern hemisphere, it is predicted to look within the northwestern-to-western sky after sundown from mid-October onward. It can be at a low altitude above the horizon and is anticipated to emit a faint glow within the twilight simply after the solar has set.

The greatest time to watch the comet is a couple of week earlier than and after its closest method. In November, the comet will cross the celestial equator and grow to be seen from the southern hemisphere.

Binoculars or small telescopes are greatest for observing it, however in the event you select a location with little gentle air pollution, you could possibly catch it with the bare eye. If you lookup on the sky simply after sundown when it’s nonetheless slightly vivid, you could possibly see it. It you might be struggling to search out the comet, use a star map software in your smartphone or planetarium software program that will help you pinpoint its location.