NEW YORK (AP) — Two bright green comets flowing through the skies and are visible to sky watchers in the Northern Hemisphere.
Both hail from the outer reaches of our solar system – perhaps so-called Oort cloudmuch further than Pluto. Comet Lemmon will approach Earth around Tuesday. Another cosmic snowball, Comet SWAN, is due to pass Earth on Monday, but it is moving away from the Sun and is likely to become dimmer as time goes on.
Finding two comets at the same time without special equipment is “rare, but not unprecedented,” said Carson Fools, director of sky research at the University of Arizona, which discovered Comet Lemmon.
To see the pair, go outside just after sunset and look to the northern sky and look for Comet Lemmon close to the horizon. Comet SWAN will also be close to the horizon, but in the southwest.
The binary comets will be visible through binoculars until the end of the month, but experts aren't yet sure how bright they will remain, said astronomer Valerie Rapson of the State University of New York at Oneonta.
Comets are the frozen remnants of the formation of the solar system billions of years ago. They heat up as they approach the sun, producing their characteristic fluttering tails.
Comet Lemmon, also designated C/2025 A6, was discovered in January by a telescope scanning the night sky for near-Earth asteroids. Comet SWAN, also known as C/2025 R2, was discovered in September by an amateur astronomer using photographs from NASA and the European Space Agency spacecraft.
Comets are green in color due to gases flowing from their surface. From Earth they will appear as gray blurry spots.
Earlier this year, a green comet disintegrated as it flew past the Sun, dashing hopes of a naked-eye spectacle. A bright comet called Tsuchinshan-Atlas approached Earth in 2024, and other notable flybys included Neowise in 2020 and Hale-Bopp and Hyakutake in the 1990s.
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