Astronomy Picture of the Day

2014-09-23 Stéphane Vetter

That's no sunset. And that thin red line just above it -- that's not a sun pillar. The red glow on the horizon originates from a volcanic eruption, and the red line is the eruption's reflection from fluttering atmospheric ice crystals. This ...

2014-09-22

rth is at equinox. Over the next 24 hours, day and night have nearly equal duration all over planet Earth. Technically, equinox transpires at 2:29 am Universal Time tomorrow, but this occurs today in North and South America. This September ...

2014-09-21

How would Saturn look if its ring plane pointed right at the Sun? Before August 2009, nobody knew. Every 15 years, as seen from Earth, Saturn's rings point toward the Earth and appear to disappear. The disappearing rings are no longer a mystery ...

2014-09-20 Bill Dickinson

Against dark rifts of interstellar dust, the ebb and flow of starlight along the Milky Way looks like waves breaking on a cosmic shore in this night skyscape. Taken with a digital camera from the dunes of Hatteras Island, North Carolina, planet ...

2014-09-19

For astrobiologists, these may be the four most tantalizing moons in our Solar System. Shown at the same scale, their exploration by interplanetary spacecraft has launched the idea that moons, not just planets, could have environments supporting ...

2014-09-18 Federico Pelliccia

In this crowded starfield covering over 2 degrees within the high flying constellation Cygnus, the eye is drawn to the Cocoon Nebula. A compact star forming region, the cosmic Cocoon punctuates a long trail of obscuring interstellar dust clouds. ...

2014-09-17 Jeremy P. Gray

It has been a good week for auroras. Earlier this month active sunspot region 2158 rotated into view and unleashed a series of flares and plasma ejections into the Solar System during its journey across the Sun's disk. In particular, a pair of ...

2014-09-16 Alex Tudorica

Galaxies, stars, and a serene reflecting pool combine to create this memorable land and skyscape. The featured panorama is a 12-image mosaic taken last month from the Salar de Atacama salt flat in northern Chile. The calm water is Laguna Cejar, a ...

2014-09-15

Spacecraft Rosetta continues to approach, circle, and map Comet Churyumov-Gerasimenko. Crossing the inner Solar System for ten years to reach the vicinity of the comet last month, the robotic spacecraft continues to image the unusual double-lobed ...

2014-09-14 Bill Snyder

The first hint of what will become of our Sun was discovered inadvertently in 1764. At that time, Charles Messier was compiling a list of diffuse objects not to be confused with comets. The 27th object on Messier's list, now known as M27 or the ...