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 January 28 
Comet G3 ATLAS over Uruguay Image Credit & Copyright: Mauricio Salazar Explanation: Comets can be huge.When far from the Sun, a comet's size usually refers to its hard nucleus of ice and rock, which typically spans a few kilometers -- smaller than even a small moon.When nearing the Sun, however, this nucleus can eject dust and gas and leave a thin tail that can spread to an enormous length -- even greater than the distance between the Earth and the Sun.Pictured, C/2024 G3 (ATLAS) sports a tail of sunlight-reflecting dust and glowing gas that spans several times the apparent size of a full moon, appearing even larger on long duration camera images than to the unaided eye.The featured image shows impressive Comet ATLAS over trees and a grass field in Sierras de Mahoma, San Jose, Uruguay about a week ago. After being prominent in the sunset skies of Earth's southern hemisphere, Comet G3 ATLAS is now fading as it moves away from the Sun, making its impressive tails increasingly hard to see. Gallery: Comet ATLAS (G3) Tomorrow's picture: star circles <| Archive| Submissions | Index| Search| Calendar| RSS| Education| About APOD| Discuss| > Authors & editors: Robert Nemiroff(MTU) &Jerry Bonnell (UMCP)NASA Official: Amber StraughnSpecific rights apply.NASA Web Privacy,Accessibility, Notices; A service of:ASD atNASA /GSFC, NASA Science Activation& Michigan Tech. U.
