On October 21, 2025, comet C/2025 A6 (Lemmon) will make its closest approach to Earth, reaching a distance of about 90 million kilometers. Residents of Russia will be able to observe it with amateur telescopes in the constellation Boötes in the evening sky, according to Lyudmila Koshman, astronomer and head of the methodological support department of the Moscow Planetarium.
The comet was discovered on January 3, 2025. Its orbit allows the object to be observed in the Northern Hemisphere, including Russia, in October and November. By November 8, the comet will reach its peak brightness — 8 stellar magnitude, which will make it visible even with binoculars.
In early September, it is located in the constellation Gemini, near the bright stars Castor and Pollux, and is available for observation in professional telescopes in the night and pre-dawn sky. In autumn, the comet will pass through the constellations Lynx, Ursa Major, Canes Venatici, Boötes, Serpens, Hercules, and Ophiuchus.
By November 20, the comet will become less visible due to evening twilight. It is recommended to use amateur telescopes or binoculars for observation, especially during the period of maximum brightness. Accurate coordinates and observation times can be found in astronomical reference books, added Koshman.
C/2025 A6 (Lemmon) is a long-period comet. It moves in a retrograde orbit, making one revolution around the Sun in approximately 1 396.20 Earth years.
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