Sculpted by stellar winds and radiation, a magnificent interstellar dust cloud by chance has assumed the shape of a horse. Fittingly named the Horsehead Nebula, light from it takes about 1,500 light-years to reach us.

It is embedded in the vast Orion cloud complex within the Orion constellation. Although the constellation is easily visible in the evening sky towards the south, it is very difficult to see the Horsehead Nebula through the telescope, as a large telescope and dark skies are required.

About five light-years “tall”, the dark cloud is visible only because its obscuring dust is silhouetted against the glowing red emission nebula IC 434 in the background.

The gigantic gas clouds making up the Horsehead Nebula have been captured excellently by Leonard Ellul-Mercer in this colour image shot by the skilful use of astronomical cameras through his telescope.

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, ionised by the nearby bright star Sigma Orionis. Streams of gas leaving the nebula are funnelled by a strong magnetic field.

Bright spots in the Horsehead Nebula’s base are young stars just in the process of forming. Like clouds in Earth’s atmosphere, this cosmic cloud has assumed a recognisable shape by chance. After many thousands of years, the internal motions of the cloud will alter its appearance as like everything else in the universe, everything is in a continuous state of motion.

Astronomical events this month

February 8: Mercury closer to the planet Mars (evening sky).
February 10: New moon at 8.20am.
February 11: The moon close to the planets Mercury and Mars (evening sky).
February 17: First quarter moon at 9.31pm.
February 25: Full moon at 9.26pm.

For up-to-date information visit our new website www.maltastro.org

Alexei Pace is president of the Astronomical Society of Malta.