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 November 17
A starfield is shown above a mountain peak. Just
above the mountain and extending up toward the upper 
right is a blue-tinted tail of a comet. The comet's
head is just to the left of the peak.  
Please see the explanation for more detailed information.

Comet Lemmon's Wandering Tail
Image Credit: Ignacio Fernández

Explanation: What has happened to Comet Lemmon's tail? The answer is blowing in the wind — the wind from the Sun in this case. This continuous outflow of charged particles from the Sun has been quite variable of late, as the Sun emits bursts of energy, CMEs, that push out and deflect charged particles emitted by the comet itself. The result is a blue hued ion tail for Comet C/2025 A6 (Lemmon) that is not only impressively intricate but takes some unusual turns. This long-duration composite image taken from Alfacar, Spain last month captured this inner Solar System ionic tumult. Comet Lemmon is now fading as it heads out away from the Earth and Sun and back into the outer Solar System.

Tomorrow's picture: radio milky way


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