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.

2026 April 20
A starry sky is seen above two tree-covered mountains
that slope up on both sides of the image. In the central
valley the head of a comet is seen, with a long tail 
flowing nearly vertically upward toward the top of the 
tall frame. 
Please see the explanation for more detailed information.

Comet R3 PanSTARRS over a Himalayan Valley
Image Credit & Copyright: Basudeb Chakrabarti & Samit Saha

Explanation: The best way to see comet R3 PanSTARRS’s long tail is with a camera. This week, the recently brightened comet appears in northern skies to the east just before dawn, but is only barely visible to the unaided eye. The many-degree ion tail captured on long duration camera exposures is not unusual for a comet - it is primarily due to the Earth's nearly sideways view of the tail as it points away from the Sun. In the featured image taken last week, Comet C/2025 R3 (PanSTARRS) showed off its flowing tail through a valley between two peaks in the Himalayan mountains of India.   The comet passed its closest to the Sun yesterday. As it nears its closest approach to Earth next week, a bushy dust tail may become visible. The comet is slowly moving out of northern skies and by the end of the month will be visible after sunset in southern skies as it fades and leaves our Solar System

Growing Gallery: Comet R3 PanSTARRS in 2026
Tomorrow's picture: different mountains


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