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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.

NGC 4755: A Jewel Box of Stars

Explanation: The great variety of star colors in this open cluster underlies its name: The Jewel Box . One of the bright central stars is a red supergiant , in contrast to the many blue stars that surround it. The cluster , also known as Kappa Crucis contains just over 100 stars, and is about 10 million years old. Open clusters are younger, contain few stars, and contain a much higher fraction of blue stars than do globular clusters . This Jewel Box lies about 6,400 light-years away, so the light that we see today was emitted from the cluster before even the Great Pyramids in Egypt were built. The Jewel Box, pictured above , spans about 20 light-years, and can be seen with binoculars towards the southern constellation of the cross ( Crux ).

Date August 17, 2010
Credit Credit & Copyright: Dieter Willasch ( Astro-Cabinet )
Authors & editors: Robert Nemiroff (MTU) & Jerry Bonnell (UMCP)
A service of: ASD at NASA / GSFC,
NASA Science Activation & Michigan Tech. U.