Photo of the Day Like salsa verde on your favorite burrito, a green aurora slathers up the sky in this 2017 June 25 snapshot from the International Space Station. About 400 kilometers (250 miles) above Earth, the orbiting station is itself within the upper realm of the auroral displays. Aurorae have the signature colors [...]
Photo of the Day Comet R3 PanSTARRS might be best remembered as an Orion comet. A key reason is because Comet C/2025 R3 (PanSTARRS) was near its most spectacular -- in terms of tail visibility -- when passing in front of the iconic constellation. Although rare, other bright comets, too, have ventured across Orion, [...]
Photo of the Day What are some of the most interesting astronomical objects you can see in the night sky? Armed with a good pair of binoculars or a small telescope, if you live in the Northern Hemisphere, you can look for the very popular objects in the Messier Catalog. Most of them, but [...]
Photo of the Day The New General Catalog of star clusters and nebulae really isn't so new. In fact, it was published in 1888 - an effort by J. L. E. Dreyer to consolidate the work of astronomers William, Caroline, and John Herschel along with others into a useful single, complete catalog of astronomical [...]
Photo of the Day Today’s composite image features something old, something new, something borrowed, and something blue! Comet R3 PanSTARRS, streaking across the right of the image, likely originated from the Oort Cloud, meaning it is an old Solar System relic from billions of years ago. It’s bright extended ion tail glows blue as [...]
Photo of the Day These people are not in danger. What is coming down from the left is just the Moon, far in the distance. Luna appears so large here because she is being photographed through a telescopic lens. What is moving is mostly the Earth, whose spin causes the Moon to slowly disappear [...]
Photo of the Day Orion never had a sword like this. As Comet C/2025 R3 (PanSTARRS) heads out of the inner Solar System, it is putting on quite a show for long exposure cameras. Currently seen toward the constellation of Orion the Hunter, the distant Orion Nebula is visible on the upper right. Comet [...]
Photo of the Day Which way is Comet R3 PanSTARRS going? Not towards the star at the top of the image, because that is Rigel, which, being far in the background, is unrelated to the comet. Not through the nebula in the image middle, because that is the Witch Head Nebula and it, too, [...]
Photo of the Day What does it mean for Saturn and Neptune to be in retrograde? Featured is a composite of images taken over 34 nights from May 2025 to February 2026 tracing Saturn (brighter, foreground) and Neptune (dimmer, background). Over that time, the two planets exhibited retrograde motion, meaning they appeared to move [...]
Photo of the Day No, Earth did not recently acquire six more moons! Today’s APOD is a combination of images following the Moon, Venus, and the Pleiades across a southern Sicilian sky as twilight turned to evening on April 19. From 2023 to 2029, the Pleiades' and the Moon “visit" each other once per [...]
