February 24, 2009
Long before your first heartbeat, stars were busy forging the elements you would one day call your own.
Barnard's Loop around the Horsehead Nebula
Birthday · February 24, 2009
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APOD published February 24, 2009. Credit: Drew Sullivan (Ancient Starlight). A publication-date match, not a photo taken on your date. Independent of NASA.
Why is the Horsehead Nebula surrounded by a bubble? Although hard to make out, the famous Horsehead Nebula is the slight dark indentation in the bright streak just to the left of the image center. Glowing like an emission nebula, the origin of the bubble, known as Barnard's Loop, is currently unknown. Progenitor hypotheses include the winds from bright Orion stars and the supernovas of stars long gone. Barnard's Loop is too faint to be identified with the unaided eye. The nebula was discovered only in 1895 by E. E. Barnard on long duration film exposures. The above image was taken in a single specific color emitted by hydrogen to bring out detail. To the left of the Horsehead Nebula, visible as a small dark indentation, is the photogenic Flame Nebula.
Image credit: Drew Sullivan (Ancient Starlight)