The picturesque Horsehead nebula is one of the most photographed objects in the sky and to celebrate the 11th birthday of the Hubble Space Telescope, the orbiting observatory took a close-up look at this heavenly icon.

The Horsehead is a cold, dark cloud of gas and dust, silhouetted against the bright gas cloud designated IC 434.

The bright area at the top left edge is a young star still embedded in the gas and dust. Intense radiation from this hot star is eroding the stellar nursery. The top of the nebula is also being sculpted by radiation from a massive star located out of Hubble's field of view.

The Horsehead's unusual shape was first discovered on a photographic plate in the late 1800s. Located in the constellation Orion, the Horsehead is a cousin of the famous pillars of dust and gas known as the Eagle nebula. Both nebulae are cocoons of young stars.

The nebula lies just south of the bright star Zeta Orionis, which is easily visible to the unaided eye as the left-hand star in the line of three that form Orion's Belt.

Amateur astronomers often use the Horsehead as a test of their observing skills; it is known as one of the more difficult objects to see visually in an amateur-sized telescope.

This popular celestial target was the clear winner among more than 5,000 internet voters, who were asked last year to select an astronomical target for the Hubble telescope to observe. The voters included students, teachers, and professional and amateur astronomers.