Stargazers across the Northern Hemisphere are in for a rare celestial treat: two vibrant green comets are streaking through the skies, offering an unusual opportunity to witness a double comet display. Both travelers hail from the distant reaches of our solar system likely the Oort Cloud, a vast icy region far beyond Pluto.
Comet Lemmon, officially cataloged as C/2025 A6, is poised for its closest approach to Earth around Tuesday, promising the brightest view of the two. Its companion, Comet SWAN (C/2025 R2), is set to make its nearest pass on Monday. However, as it moves away from the sun, SWAN is expected to gradually fade from view.
âSeeing two comets at the same time without specialized equipment is unusual, but certainly not unprecedented,â said Carson Fuls, director of the University of Arizona-based sky survey responsible for spotting Comet Lemmon.
Observers are advised to step outside just after sunset. Look toward the northern horizon to catch Comet Lemmon, which will appear low in the sky. Meanwhile, Comet SWAN can be glimpsed near the southwestern horizon. With a good pair of binoculars, both comets may remain visible through the end of October, though astronomers caution that their brightness could fluctuate. Valerie Rapson, an astronomer at the State University of New York at Oneonta, noted, âItâs always tricky to predict exactly how luminous these comets will be as they move farther from the sun.â
Comets are ancient relics from the solar systemâs formation, composed of ice, dust, and frozen gases. As they approach the sun, these frozen bodies heat up and release gases, forming the characteristic glowing tails that captivate onlookers. The green hue seen in Lemmon and SWAN originates from these gases, though from Earth the comets will mostly appear as fuzzy, grayish patches against the night sky.
Discovered in January 2025, Comet Lemmon was identified by a telescope designed to track near-Earth asteroids. Comet SWAN, on the other hand, was first noticed in September by an amateur astronomer analyzing images from a NASA and ESA-operated spacecraft.
Double comet sightings are a memorable occurrence for astronomers and sky enthusiasts alike. While earlier this year, hopes for a naked-eye comet spectacle were dashed when a green comet disintegrated near the sun, the current twin display offers a more promising spectacle. History is dotted with such memorable flybys, including Comet Tsuchinshan-Atlas in 2024, Neowise in 2020, and the famous Hale-Bopp and Hyakutake comets of the 1990s.
For those eager to catch this fleeting cosmic show, clear skies and an unobstructed horizon are key. The twin green comets offer not just a visual delight but a poignant reminder of the ancient origins of our solar system, silently journeying from the outermost edges to grace our night sky.