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Astronomy Picture of the Day

Discover the cosmos! Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer.

A starfield is shown that has a bright comet. The comet shows a green head on the lower left and an ion tail with significant structure extending out to the upper right. Please see the explanation for more detailed information.

Comet Lemmon Brightens

Explanation: Comet Lemmon is brightening and moving into morning northern skies. Besides Comet SWAN25B and Comet ATLAS , Comet C/2025 A6 (Lemmon) is now the third comet currently visible with binoculars and on long camera exposures. Comet Lemmon was discovered early this year and is still headed into the inner Solar System . The comet will round the Sun on November 8, but first it will pass its nearest to the Earth -- at about half the Earth-Sun distance -- on October 21. Although the brightnesses of comets are notoriously hard to predict , optimistic estimates have Comet Lemmon then becoming visible to the unaided eye. The comet should be best seen in predawn skies until mid-October, when it also becomes visible in evening skies. The featured image showing the comet's split and rapidly changing ion tail was taken in Texas , USA late last week.

Growing Gallery: Comet Lemmon in 2025

Date September 30, 2025
Credit Image Credit & Copyright: Victor Sabet & Julien De Winter
Authors & editors: Robert Nemiroff (MTU) & Jerry Bonnell (UMCP)
A service of: ASD at NASA / GSFC,
NASA Science Activation & Michigan Tech. U.