December 31, 2013
On the day you were born, another consciousness opened inside the cosmos and began taking notes.
The Horsehead Nebula
Birthday · December 31, 2013
A little universe, just for you
Your date.
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APOD published December 31, 2013. Credit: John Chumack. A publication-date match, not a photo taken on your date. Independent of NASA.
The Horsehead Nebula is one of the most famous nebulae on the sky. It is visible as the dark indentation to the red emission nebula in the center of the above photograph. The horse-head feature is dark because it is really an opaque dust cloud that lies in front of the bright red emission nebula. Like clouds in Earth's atmosphere, this cosmic cloud has assumed a recognizable shape by chance. After many thousands of years, the internal motions of the cloud will alter its appearance. The emission nebula's red color is caused by electrons recombining with protons to form hydrogen atoms. Also visible at the bottom left of the picture is a greenish reflection nebulae that preferentially reflects the blue light from nearby stars. Free lecture: APOD editor to speak in NYC on Jan. 3
Image credit: John Chumack