Sunspot at Sunset
8.01.2014

Sunsets may be the most watched celestial event, but lately sunsets have even offered something extra. A sunspot so large it was visible to the naked eye is captured in Swiss skies in this...

A Rainbow Pileus Cloud over Zimbabwe
19.02.2014

Yes, but how many dark clouds have a multicolored lining? Pictured, behind this darker cloud, is a pileus iridescent cloud, a group of water droplets that have a uniformly similar size and so together diffract different colors of sunlight by different amounts.

45 Days in the Sun
20.02.2015

From January 11 to February 25 2013, a pinhole camera sat in a field near Budapest, Hungary, planet Earth to create this intriguing solargraph. And for 45 days, an old Antonov An-2 biplane stood still while the Sun rose and set.

Close Mars
31.08.2018

Still bright in evening skies, Mars was just past opposition and closest to Earth on July 31, a mere 57.6 million kilometers away. Captured only a week later, this remarkable image shows...

Comet Wirtanen Passes by the Earth
16.12.2018

Today Comet Wirtanen passes by the Earth. The kilometer-sized dirty snowball orbits the Sun every 5.4 years, ranging as far out as Jupiter and as close in as the Earth. Today Comet 46P/Wirtanen passes within only 31 lunar distances to the Earth, the closest approach in 70 years.

APOD: 2023 January 3 Б Kembles Cascade of Stars
3.01.2023

This line of stars is real. A little too faint to see with the unaided eye, KembleБs Cascade of stars inspires awe when seen with binoculars. Like the Big Dipper though, KembleБs Cascade is an asterism, not a constellation. The asterism is visible in the northern sky toward the long-necked constellation of the Giraffe (Camelopardalis).

Messier 4
29.11.2024

Messier 4 can be found west of bright red-giant star Antares, alpha star of the constellation Scorpius. M4 itself is only just visible from dark sky locations, even though the globular cluster of 100,000 stars or so is a mere 5,500 light-years away.

Heaven on Earth
6.11.2000

If sometimes it appears that the entire Milky Way Galaxy is raining down on your head, do not despair. It happens twice a day. As the Sun rises in the East, wonders of the night sky become less bright than the sunlight scattered by our own Earth's atmosphere, and so fade from view.

Aurora at Midnight
5.05.1998

What's happening behind those trees? Aurora. This picture was taken at midnight near Fairbanks, Alaska, and captures familiar trees, common clouds, and a glowing sky markedly different than a sunset. Particularly strange is the green auroral ring caused by ionized oxygen high in the Earth's atmosphere.

Globular Cluster M2
11.06.2001

Beneath the south pole of our Milky Way Galaxy lies a ball of over 100,000 stars. M2, the second object on Charles Messier's eighteenth century list of bright diffuse sky objects...