Astronomy Picture Of the Day (APOD)1006 AD: Supernova in the Sky
A new star, likely the brightest supernova in recorded human history, appeared in planet Earth's sky in the year 1006 AD. The expanding debris cloud from the stellar explosion is still visible to modern astronomers, but what did the supernova look like in 1006?
Light Echoes from V838 Mon
Nominated for most mysterious star in the Milky Way, V838 Monocerotis briefly became one of the brightest stars in our galaxy. Its outburst discovered in January 2002, observations have indicated that V838 Mon somehow...
A Lenticular Cloud Over Wyoming
Is that a cloud or a flying saucer? Both, although it is surely not an alien spacecraft. Lenticular clouds can be shaped like a saucer, and can fly in the sense that, like most clouds, they are composed of small water droplets that float on air.
A Slow Explosion
Why would a gamma ray burst fade so slowly? This behavior, recorded last October, is considered a new clue into the cause of gamma-ray bursts, the most powerful explosions known in the universe.
A Digital Sunset Over Europe and Africa
No single spacecraft or astronaut took this picture. It is a digital composite of archived images taken over many orbits by several Earth-orbiting satellites. Similar images can be digitally stitched together for any Earth location by John Walker's Earth and Moon Viewer website.
Alpha Centauri: The Closest Star System
The closest star system to the Sun is the Alpha Centauri system. Of the three stars in the system, the dimmest -- called Proxima Centauri -- is actually the nearest star. The bright stars Alpha Centauri...
M57: The Ring Nebula
Except for the rings of Saturn, the Ring Nebula (M57) is probably the most famous celestial band. This planetary nebula's simple, graceful appearance is thought to be due to perspective -- our view from planet Earth looking straight into what is actually a barrel-shaped cloud of gas shrugged off by a dying central star.
Stars and Planets in the Halo of the Moon
Photographed on March 13th from Caledon, Ontario, Canada, a bright Moon was surrounded by this lovely halo. Planet Jupiter and stars Procyon, Castor, and Pollux also appear within the circle of lunar light. Castor...
Astronomically speaking, at the Equinox on March 21, 01:00 UT (March 20, 8:00 PM ET) the season changes. For this Equinox the Sun rises due east as it crosses the celestial equator heading north. In celebration, consider this spectacular sunrise analemma!
Jupiter's Great Dark Spot
Seventeenth century astronomer Giovanni Domenico Cassini was an astute observer of Jupiter's Great Red Spot. So it seems only fitting that his namesake, the Cassini spacecraft, has enabled detailed observations of another planet-sized blemish -- Jupiter's Great Dark Spot.