Friday, January 21, 2011

APOD 3.1



This star cluster is in the southern sky, and it spans about 120 light years.  It is approximately 13,000 light years away from Earth.  It is the largest cluster visible from Earth and the second brightest, but due to its low declination, it was cataloged as a star until 1751.  47 Tucanae is moving toward Earth at about 19 km/s.   The cluster is located in the Halo of the Milky Way Galaxy, which means that most of its time is spent outside of the disk of the galaxy in a more elliptical orbit.  Since it is so bright, it can be seen with the naked eye, near the  Small Magellanic Cloud.  It also houses x-ray binary star systems, as I previously referred to in another entry.

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