Andromeda Galaxy

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Andromeda is a spiral galaxy approximately 2.5 million light-years away from Earth. The largest of our nearest galactic neighbors, its disk is about 260,000 light-years in diameter. The disc of the Milky Way galaxy, our own, is considerably smaller, approximately 100,000 light years across.[1]

Andromeda Galaxy: Composite of Galaxy Evolution Explorer ultraviolet detectors and Spitzer's super-sensitive infrared imaging photometer disclose embryonic stars. Young, hot, high-mass stars (blue); older stars (green); Bright yellow spot at the galaxy's center - a particularly dense population of old stars; Cooler, dusty regions where stars are forming (red swaths); Populations of hot, high-mass stars and cooler, dust-enshrouded stars co-exist (pinkish purple areas).

Stars

Andromeda contains approximately 1,000,000,000,000 stars (one trillion). The Milky Way by comparison contains about 200,000,000 (two hundred billion). Conversely, new measurements employing infrared technolgy indicate that Andromeda's energy output is about that of 4,000,000,000 (four billion) suns. The most recent measurements concur with earlier estimates of the mass of the galaxy however.[2]

References