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Moon Over Andromeda
| Title |
Moon Over Andromeda |
| Explanation |
The Great Spiral Galaxy in Andromeda [ http://antwrp.gsfc.nasa.gov/apod/ap051222.html ] (aka M31), a mere 2.5 million light-years distant [ http://arxiv.org/abs/astro-ph/0511045 ], is the closest large spiral to our own Milky Way. Andromeda is visible to the unaided eye as a small, faint, fuzzy patch, but because its surface brightness is so low, casual skygazers [ http://www.physics.ucla.edu/~huffman/m31.html ] can't appreciate the galaxy's impressive extent in planet Earth's sky. This entertaining composite image compares the angular size [ http://chandra.harvard.edu/photo/scale.html ] of the nearby galaxy to a brighter, more familiar celestial sight. In it, a deep exposure of Andromeda [ http://www.caelumobservatory.com/gallery/m31abtp.shtml ], tracing beautiful blue star clusters in spiral arms far beyond the bright yellow core, is combined with a typical view of a nearly full Moon. Shown at the same angular scale, the Moon covers about 1/2 degree on the sky, while the galaxy is clearly [ http://www.regulusastro.com/regulus/papers/ m31/ ] several times that size. The deep Andromeda exposure also includes two bright satellite galaxies, M32 [ http://antwrp.gsfc.nasa.gov/apod/ap991103.html ] and M110 [ http://antwrp.gsfc.nasa.gov/apod/ap060908.html ] (bottom). |
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Bright Star Regulus near the
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| Title |
Bright Star Regulus near the Leo 1 Dwarf Galaxy |
| Explanation |
The star on the upper left is so bright it is sometimes hard to notice the galaxy on the lower right. Both the star, Regulus [ http://en.wikipedia.org/wiki/Regulus ], and the galaxy, Leo I [ http://en.wikipedia.org/wiki/Leo_I_(dwarf_galaxy) ], can be found within one degree of each other toward the constellation of Leo. Regulus [ http://www.astro.uiuc.edu/~kaler/sow/regulus.html ] is part of a multiple star system [ http://homepage.univie.ac.at/peter.wienerroither/pwafods/10084+1158.htm ], with a close companion double star [ http://antwrp.gsfc.nasa.gov/apod/ap970219.html ] visible to the upper right of the young main sequence [ http://observe.arc.nasa.gov/nasa/space/stellardeath/stellardeath_1ai.html ] star. Leo I is a dwarf spheroidal galaxy [ http://www.astro.uu.se/~ns/review.html ] in the Local Group [ http://www.seds.org/messier/more/local.html ] of galaxies dominated by our Milky Way Galaxy [ http://antwrp.gsfc.nasa.gov/apod/ap980523.html ] and M31 [ http://antwrp.gsfc.nasa.gov/apod/ap051222.html ]. Leo I is thought to be the most distant of the several known small satellite galaxies [ http://www.astro.uu.se/~ns/mwsat.html ] orbiting our Milky Way Galaxy [ http://antwrp.gsfc.nasa.gov/apod/ap971229.html ]. Regulus is located about 75 light years [ http://starchild.gsfc.nasa.gov/docs/StarChild/questions/question19.html ] away, in contrast to Leo 1 which is located about 800,000 light years away. |
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