Astronomy Picture of the Day for June 14

Astronomy Picture of the Day

Discover the cosmos! Each day a different image or photograph of our fascinating universe is  featured, along with a brief explanation written by a professional astronomer.

2012 June 14

M13: The Great Globular Cluster in Hercules

Image Credit & Copyright: Martin Pugh  

 

 

Explanation: In 1716, English astronomer Edmond Halley noted, “This is but a little Patch, but it shews itself to the naked Eye, when the Sky is serene and the Moon absent.” Of course, M13 is now modestly recognized as the Great Globular Cluster in Hercules, one of the brightest globular star clusters in the northern sky. Telescopic views reveal the spectacular cluster’s hundreds of thousands of stars. At a distance of 25,000 light-years, the cluster stars crowd into a region 150 light-years in diameter, but approaching the cluster core upwards of 100 stars could be contained in a cube just 3 light-years on a side. For comparison, the closest star to the Sun is over 4 light-years away. Along with the cluster’s dense core, the outer reaches of M13 are highlighted in this sharp color image. The cluster’s evolved red and blue giant stars show up in yellowish and blue tints.

Astronomy Picture of the Day for November 3rd

Astronomy Picture of the Day

Discover the cosmos!Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer.

See Explanation.  Clicking on the picture will download the highest resolution version available.

Tails of Comet Garradd
Image Credit & Copyright: Gregg Ruppel 

 

Explanation: A good target for binoculars and small telescopes, Comet Garradd (C/2009 P1) now shines in planet Earth’s evening skies, a steady performer but just below naked-eye visibility. Telescopic images like this composite from October 15 can find the comet with a lovely green coma, sporting multiple tails, and lingering against a background of faint stars. The field of view spans over 1 degree or about 2 full moons within the southern boundaries of the constellation Hercules. Now around 16 light minutes (2 astronomical units) away, P1 Garradd is an intrinsically large comet, but will never make a very close approach to Earth or the Sun while sweeping through the inner solar system. As a result, the comet will likely stay a sight for telescopic eyes only, moving slowly through the sky and remaining in Hercules during the coming months.