A Quadruple Lunar Halo Over Spain
3.12.2012

Sometimes falling ice crystals make the atmosphere into a giant lens causing arcs and halos to appear around the Sun or Moon. This past Saturday night was just such a time near Madrid, Spain, where a winter sky displayed not only a bright Moon but as many as four rare lunar halos.

APOD: 2025 May 6 Б The Doubly Warped World of Binary Black Holes
6.05.2025

If one black hole looks strange, what about two? Light rays from accretion disks around a pair of orbiting supermassive black holes make their way through the warped space-time produced by extreme gravity in this detailed computer visualization.

Star Trails in Northern Skies
12.09.1998

As the Earth spins on its axis, the sky seems to rotate around us. This motion produces the beautiful concentric trails traced by the stars in this time exposure of the night sky.

GW170817: A Spectacular Multiradiation Merger Event Detected
16.10.2017

Both gravitational and electromagnetic radiations have been detected in rapid succession for an explosive merging event for the first time. Data from the outburst fit well with a spectacular binary neutron-star death-spiral. The explosive episode was seen on August 17 in nearby NGC 4993, an elliptical galaxy only 130 million light years distant.

HR 8799: Discovery of a Multi planet Star System
17.11.2008

How common are planetary systems like our own Solar System? In the twelve years previous to 2008, over 300 candidate planetary systems have been found orbiting nearby stars. None, however, were directly imaged, few showed evidence for multiple planets, and many had a Jupiter-sized planet orbiting inside the orbit of Mercury.

Echoes of Supernova 1987A
23.10.1997

Can you find Supernova 1987a? It's not hard - it occurred in the center of the bulls-eye pattern. Although this stellar detonation was seen more than a decade ago, light from it continues to bounce off nearby interstellar dust and be reflected to us. These two rings are thus echoes of the powerful supernova.

An Airplane in Front of the Moon
29.09.2010

If you look closely at the Moon, you will see a large airplane in front of it. Well, not always. OK, hardly ever. But if you wait for days with your camera attached to a Moon tracker in a place where airplanes are known to pass, you might catch a good photograph of it.

Star Trails in Northern Skies
1.12.1996

As the Earth spins on its axis, the sky seems to rotate around us. This motion produces the beautiful concentric arcs traced out by the stars in this time exposure of the night sky.

Star Trails in Southern Skies
26.09.1995

As the Earth spins on its axis, the sky seems to rotate around us. This motion produces the beautiful concentric arcs traced out by the stars in this time exposure of the night sky. In the foreground of the picture is the dome of the Anglo-Australian Telescope in central New South Wales Australia.

M55 Color Magnitude Diagram
23.02.2001

This color "picture" of globular star cluster M55 may not look like any star cluster you've ever seen. Still, it shows a most fundamental view for students of stellar astronomy. In the picture...