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.

2025 October 20
A night sky is seen over a lake. The sky contains
numerous stars including the Big Dipper asterism. Prominent
in the sky is a comet with a long tail. Both the Big Dipper
and the comet are seen reflected in the still water of the 
lake.
Please see the explanation for more detailed information.

Finding Comet Lemmon
Image Credit & Copyright: Petr Horalek / Institute of Physics in Opava

Explanation: Tonight, if you can see the stars of the Big Dipper, then you can find comet Lemmon in your evening sky. After sunset, look for the faint but extended comet above your northwestern horizon -- but below the handle of the famous celestial kitchen utensil of the north. It might be easier to see this visitor to the inner Solar System through your camera phone, which is better at picking up faint objects. Either way, look for a fuzzy green 'star' with a tail, though probably not so long a tail as in this impressive snapshot taken over Seč Lake in the Czech Republic two nights ago. Recent photographs of C/2025 A6 (Lemmon) often show a detailed and changing ion tail which extends farther than the eye can follow. This Sun-orbiting comet is now near its closest approach to Earth and will pass its closest to the Sun in early November.

Tomorrow's picture: big heart


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