The constellation of Orion is one of the most recognizable patterns in our night sky.
Within its boundaries lies the Orion Molecular Cloud Complex, located some 1,500 light years away.
Inside this complex, on the farthest eastern edge of Orion's belt, is one of the most photographed
nebulae in astronomy: The Horsehead Nebula.
This nebula was first recorded in 1888 by Scottish astronomer Williamina Fleming at
the Harvard College Observatory and ever since, we have been captivated by it.
The red or pinkish glow originates from hydrogen gas predominantly behind the nebula, ionized
by the nearby bright star Sigma Orionis, which is really a young, five-star system just out of view.
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 beginning to form.
Since 1888, this has been our main view of the Horsehead Nebula and it has become an icon.
But in April, 2013, astronomers using the Hubble Space Telescope released another view.
One that only Hubble's infrared cameras in space could provide.
Here is the Horsehead Nebula in the infrared.
In the Hubble image, the backlit wisps along the Horsehead's upper ridge illuminated by
Sigma Orionis can be seen.
Two fledgling stars peek out from their now-exposed nurseries.
This nebula gets it shape from powerful forces within this stellar cradle.
Harsh ultraviolet radiation from one of these bright stars is slowly evaporating the nebula.
Gas clouds surrounding the Horsehead already have dissipated, but the tip of the jutting
pillar contains a slightly higher density of hydrogen and helium, laced with dust.
This casts a shadow that protects material behind it from being stripped away by intense stellar
radiation evaporating the hydrogen cloud, and a pillar structure forms.
The Hubble Space Telescope has been providing us with ground-breaking science for two decades.
And every once in a while, it takes time out to give us a portrait
of familiar friends in a completely new light.
