The Great Orion Molecular Nebula -Messier 42

A composite of two images taken with my 127mm Meade apo-refracting telescope and Canon 400D and 600D DSLR cameras

After I finished imaging Comet Lovejoy, I decided to take a few frames of the wonderful Orion Nebula.

Messier 42 (aka. NGC1976) is an enormous cloud of diffuse gas and dust lying some 1350 light years distant from Earth. Imaging M42 is difficult because a time exposure long enough to capture the wispy filaments of nebulosity results in burn out of the brighter core and the cluster of bright young stars at its centre, known as the Trapezium.

The Trapezium star cluster - my image using ESO data

The Nebula is part of a much larger nebula that is known as the Orion Molecular Cloud Complex. The Orion Molecular Cloud Complex extends throughout the constellation of Orion and includes Barnard's Loop, the Horsehead Nebula, M43, M78, and the Flame Nebula. Stars are forming throughout the Orion Nebula, and due to this heat-intensive process the region is particularly prominent in the infrared.


 The nebula forms a roughly spherical cloud that peaks in density near the core. The cloud has a temperature ranging up to 10,000 K, but this temperature falls dramatically near the edge of the nebula. If you were flying through this gas and dust cloud in your spacesuit  you would not be incinerated. Temperature is a measure of the kinetic energy of the particles of dust and gas molecules in the cloud. It is not a measure of heat.  Because the gas is so diffuse and although the energy of its constituent particles is high, localised levels of heat within the nebula are very low. It would be good however, to keep well away from the young blue stars of the Trapezium star cluster as they are beaming out copious amounts of ionising ultra violet radiation.

Unlike the density distribution, the cloud displays a range of velocities and turbulence, particularly around the core region. Relative movements are up to 10 km/s (22,000 mi/h), with local variations of up to 50 km/s and possibly more.

The current astronomical model for the nebula consists of an ionized region roughly centered on Theta¹ Orionis C, the star responsible for most of the ultraviolet ionizing radiation. (It emits 3-4 times as much photoionizing light as the next brightest star, Theta² Orionis A.) This is surrounded by an irregular, concave bay of more neutral, high-density cloud, with clumps of neutral gas lying outside the bay area. This in turn lies on the perimeter of the Orion Molecular Cloud.

Observers have given names to various features in the Orion Nebula. The dark lane that extends from the north toward the bright region is called the "Fish's Mouth". The illuminated regions to both sides are called the "Wings". Other features include "The Sword", "The Thrust", and "The Sail".

The Orion Nebula is an active nursery for the birth and early development of stars. Professional astronomers have found stars and planetary systems emerging from gravitationally collapsed and denser parts of the cloud.

 M42 is a fantastic and fascinating locality within our amazing home Milkyway Galaxy and you can see it, on any moon free clear night, just below Orion's three belt stars, with your naked eye!

Credits: Wikipedia and ESO - The European Southern Observatory