Golden Survivor: Comet C/2025 K1 (ATLAS) Defies the Sun and Glows a Rare Gold

Golden survivor: Comet C/2025 K1 (ATLAS) defies the Sun

New images show that a recently discovered comet, C/2025 K1 (ATLAS), survived a perilous close pass of the Sun and now appears as a striking golden ribbon — a fate many astronomers expected would destroy it.

Discovery and close approach. The comet was first spotted in May by the Asteroid Terrestrial-impact Last Alert System (ATLAS), which searches the sky with telescopes in Hawaii, Chile and South Africa. C/2025 K1 reached perihelion (its closest point to the Sun) on Oct. 8, drawing as close as roughly 31 million miles (50 million kilometers). That is about four times closer than the interstellar visitor 3I/ATLAS reached at its Oct. 29 perihelion, and many observers feared the intense thermal and tidal stresses would shred the comet.

Stunning photography and color. On Oct. 29, astrophotographer Dan Bartlett captured a vivid image of C/2025 K1 from June Lake, California, showing a distinct golden to reddish-brown glow and a long tail sculpted by the solar wind. At least two other photographers in California and Arizona reported matching coloration. The visual effect resembles Comet Lemmon after its tail was dramatically altered by solar interaction, but the gold hue remains unusual.

"This comet was not supposed to survive its Oct. 8th perihelion," Bartlett told Spaceweather.com. "But it did survive, and now it is displaying a red/brown/golden color rarely seen in comets."

Why gold? Comets typically look white because they scatter sunlight across the visible spectrum. Specific chemical species in the coma (the cloud of gas, ice and dust around a nucleus) can absorb or emit at particular wavelengths, producing colors. Green comets, for example, are often marked by dicarbon (C2) or cyanide emissions; blue tints can indicate carbon monoxide or ammonia.

Observations reported by astronomer David Schleicher (Lowell Observatory) indicate that C/2025 K1 is unusually depleted in carbon-bearing molecules such as dicarbon, carbon monoxide and cyanide — only two other known comets show as few of these compounds. That relative lack of carbon-bearing gases, combined possibly with a low gas-to-dust ratio or recent effects from the close solar flyby, is the leading explanation for the comet's rare golden hue, although researchers say the exact cause is not yet certain.

Brightness and viewing tips. C/2025 K1 currently shines at an apparent magnitude near 9, similar to how bright 3I/ATLAS became after its solar encounter. That brightness is too faint for the unaided eye but readily visible through a modest telescope or good stargazing binoculars. Skywatchers can find the comet in the eastern sky between the constellations Virgo and Leo, best viewed shortly before sunrise. The comet makes its closest approach to Earth on Nov. 25 and should remain observable into early December under clear skies.

Context. The survival and unusual coloration of C/2025 K1 add to a busy season of comet news that has included the interstellar visitor 3I/ATLAS and the dramatic displays of Comet Lemmon. Continued observations and spectroscopy will help astronomers pin down the precise composition and the processes that produced the comet's golden glow.

Sources: ATLAS survey discovery notices; Spaceweather.com coverage; blog post and spectroscopic notes from David Schleicher, Lowell Observatory; photographs by Dan Bartlett and other astrophotographers.