The Great Spiral Galaxy in Andromeda [
http://antwrp.gsfc.…] (aka M31), a mere 2.5 million light-years distant [
http://arxiv.org/ab…], 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.…] can't appreciate the galaxy's impressive extent in planet Earth's sky. This entertaining composite image compares the angular size [
http://chandra.harv…] of the nearby galaxy to a brighter, more familiar celestial sight. In it, a deep exposure of Andromeda [
http://www.caelumob…], 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.regulusa…m31/ ] several times that size. The deep Andromeda exposure also includes two bright satellite galaxies, M32 [
http://antwrp.gsfc.…] and M110 [
http://antwrp.gsfc.…] (bottom).
Explanation
The Great Spiral Galaxy in Andromeda [
http://antwrp.gsfc.…] (aka M31), a mere 2.5 million light-years distant [
http://arxiv.org/ab…], 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.…] can't appreciate the galaxy's impressive extent in planet Earth's sky. This entertaining composite image compares the angular size [
http://chandra.harv…] of the nearby galaxy to a brighter, more familiar celestial sight. In it, a deep exposure of Andromeda [
http://www.caelumob…], 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.regulusa…m31/ ] several times that size. The deep Andromeda exposure also includes two bright satellite galaxies, M32 [
http://antwrp.gsfc.…] and M110 [
http://antwrp.gsfc.…] (bottom).
Explanation
