Comet C/2025 A6 (Comet Lemmon) unexpectedly brightened in 2025 and became visible to the naked eye. A November photo from Mauna Kea shows the comet streaking past the Milky Way, with faint light pollution on the horizon. Discovered in January at Mt. Lemmon, it made closest approach in October 2025 and reached a brightness comparable to Uranus. Its orbital period is roughly 1,350 years, meaning it won’t return until about 3375.
Comet Lemmon Dazzles Skywatchers: Bright Visitor Blazes Past the Milky Way
International Gemini Observatory/NOIRLab/NSF/AURA; Image processing: M. Rodriguez (International Gemini Observatory/NSF NOIRLab) & M. Zamani (NSF NOIRLab)
Comet C/2025 A6 — popularly known as Comet Lemmon — surprised astronomers and skywatchers in 2025 by brightening enough to be seen with the naked eye. A striking November photograph from Mauna Kea captures the comet as a luminous white streak sweeping past the band of the Milky Way, creating a rare and memorable celestial tableau.
Discovered in January 2025 by observers at the Mt. Lemmon SkyCenter in Arizona's Santa Catalina Mountains, Comet Lemmon made its closest approach to Earth in October 2025. The November image was taken with Gemini North's cloud cameras at the International Gemini Observatory on the summit of Mauna Kea and also shows a faint horizon glow from nearby towns' light pollution.
Unexpected Brightness and Long Return
At the time the photo was taken, the comet's apparent brightness was comparable to that of the planet Uranus, making it visible without optical aid, according to the U.S. National Science Foundation's NOIRLab. Its performance exceeded early forecasts and delighted both amateur and professional observers.
Orbit determinations by the discovery team indicate that Comet Lemmon follows a long-period orbit of roughly 1,350 years. That means this visitor will not return to the inner solar system until around the year 3375, well beyond the span of a single human lifetime. The November photograph therefore serves as a rare visual record for many future generations.
Photo credit: International Gemini Observatory/NOIRLab/NSF/AURA. Image processing: M. Rodriguez (International Gemini Observatory/NSF NOIRLab) & M. Zamani (NSF NOIRLab).
For stargazers, Comet Lemmon offered a fleeting reminder of the beauty and scale of our solar system: a bright, transient visitor crossing the Milky Way and briefly dominating the night sky.
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