Astronomy Picture of the Day

2011-09-04

In the shadow of Saturn, unexpected wonders appear. The robotic Cassini spacecraft now orbiting Saturn drifted in giant planet's shadow for about 12 hours in 2006 and looked back toward the eclipsed Sun. Cassini saw a view unlike any other. ...

2011-09-03

Comet Garradd continues to brighten as it drifts across the northern sky. Last week the comet, visible with binoculars and discernible by its green coma, passed nearly in front of globular cluster M71. M71 was once thought to be an open cluster, ...

2011-09-02

With a 3.5 meter diameter mirror, larger than the Hubble Space Telescope, ESA's Herschel Space Observatory explores the Universe at infrared wavelengths. Herschel is named for German-born British astronomer Frederick William Herschel who ...

2011-09-01 Martin Pugh

While hunting for comets in the skies above 18th century France, astronomer Charles Messier diligently kept a list of the things he encountered that were definitely not comets. This is number 27 on his now famous not-a-comet list. In fact, 21st ...

2011-08-31

What kind of cloud is this? A type of arcus cloud called a roll cloud. These rare long clouds may form near advancing cold fronts. In particular, a downdraft from an advancing storm front can cause moist warm air to rise, cool below its dew ...

2011-08-30

This cosmic snapshot composed with image data from NASA's Wide-field Infrared Survey Explorer (WISE) satellite captures a multitude of faint stars and distant galaxies toward the constellation Lyra at wavelengths longer than visible light. But ...

2011-08-29 Stephen Leshin

Scanning the skies for galaxies, Canadian astronomer Paul Hickson and colleagues identified some 100 compact groups of galaxies, now appropriately called Hickson Compact Groups. The four prominent galaxies seen in this intriguing telescopic ...

2011-08-28

What's causing a huge jet to emanate from the center of galaxy M87? Although the unusual jet was first noticed early in the twentieth century, the exact cause is still debated. The above picture taken by the Hubble Space Telescope in 1998 shows ...

2011-08-27

How does a hurricane form? Although a complete picture is still being researched, insight into this process might be gleaned by watching the above time lapse movie of the formation of Hurricane Irene, a large storm system currently threatening ...

2011-08-26

A nearby star has exploded and telescopes all over the world are turning to monitor it. The supernova, dubbed PTF 11kly, was discovered by computer only two days ago as part of the Palomar Transient Factory (PTF) sky survey utilizing the wide ...