July 28, 2014
The cosmos has been expanding since the beginning of time, making room for galaxies, for stars, for planets — and ultimately, for you.
The Horsehead Nebula from Blue to Infrared
Birthday · July 28, 2014
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APOD published July 28, 2014. Credit: Optical: Aldo Mottino & Carlos Colazo, OAC, C�rdoba; Infrared: Hubble Legacy Archive. A publication-date match, not a photo taken on your date. Independent of NASA.
One of the most identifiable nebulae in the sky, the Horsehead Nebula in Orion, is part of a large, dark, molecular cloud. Also known as Barnard 33, the unusual shape was first discovered on a photographic plate in the late 1800s. The red glow originates from hydrogen gas predominantly behind the nebula, ionized by the nearby bright star Sigma Orionis. The darkness of the Horsehead is caused mostly by thick dust, although the lower part of the Horsehead's neck casts a shadow to the left. Streams of gas leaving the nebula are funneled by a strong magnetic field. Bright spots in the Horsehead Nebula's base are young stars just in the process of forming. Light takes about 1,500 years to reach us from the Horsehead Nebula. The above image is a digital combination of images taken in blue, green, red, and hydrogen-alpha light from the Argentina, and an image taken in infrared light by the orbiting Hubble Space Telescope. Follow APOD on: Facebook, Google Plus, or Twitter
Image credit: Optical: Aldo Mottino & Carlos Colazo, OAC, C�rdoba; Infrared: Hubble Legacy Archive