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.

2001 December 22
See Explanation.  Clicking on the picture will download
 the highest resolution version available.

Hot Stars in the Southern Milky Way
Credit: WFI, European Southern Observatory

Explanation: Hot blue stars, red glowing hydrogen gas, and dark, obscuring dust clouds are strewn through this dramatic region of the Milky Way in the southern constellation of Ara (the Altar). About 4,000 light-years from Earth, the stars at the left are young, massive, and energetic. Their intense ultraviolet radiation is eating away at the nearby star forming cloud complex - ionizing the hydrogen gas and producing the characteristic red "hydrogen-alpha" glow. At right, visible within the dark dust nebula, is small cluster of newborn stars. This beautiful color picture is a composite of images made through blue, green, and hydrogen-alpha filters.

Tomorrow's picture: Saturn Aurora

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Authors & editors: Robert Nemiroff (MTU) & Jerry Bonnell (USRA)
NASA Technical Rep.: Jay Norris. Specific rights apply.
A service of: LHEA at NASA/ GSFC
& Michigan Tech. U.