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.

2024 June 4
A dark star filled sky is shown with the wisps
extending the length of the image. The wisps are the 
two tails of Comet 12P. A particularly bright star is 
visible near the bottom of the frame.
Please see the explanation for more detailed information.

Comet Pons-Brooks Develops Opposing Tails
Image Credit & Copyright: Rolando Ligustri & Lukas Demetz

Explanation: Why does Comet Pons-Brooks now have tails pointing in opposite directions? The most spectacular tail is the blue-glowing ion tail that is visible flowing down the image. The ion tail is pushed directly out from the Sun by the solar wind. On the upper right is the glowing central coma of Comet 12P/Pons–Brooks. Fanning out from the coma, mostly to the left, is the comet's dust tail. Pushed out and slowed down by the pressure of sunlight, the dust tail tends to trail the comet along its orbit and, from some viewing angles, can appear opposite to the ion tail. The distant, bright star Alpha Leporis is seen at the bottom of the featured image captured last week from Namibia. Two days ago, the comet passed its closest to the Earth and is now best visible from southern skies as it dims and glides back to the outer Solar System.

Tomorrow's picture: mystery martian

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