Messier 42 - The Orion Nebula
Located in the sword of the constellation Orion, just below the belt, M42 is one of the most beautiful objects in the night sky.
Easily seen through even a modest set of binoculars, M42 resembles a large ball of gas, cut open on one side. In its interior lies four extremely bright stars, which are producing the ionising radiation responsible for the brilliant colour of the nebula (which can only been seen post-processed). These four stars are known as the asterism (recognisable pattern) called the Trapezium Cluster.
Due to it’s naked-eye visibility, any determination of a first discovery can be thrown out. Yet we may note that, interestingly, the Mayans could well have mentioned the nebula in their creation myth. The first true scientific insight to the nebula was made in 1610 by Nicolas-Claude Fabri de Peiresc, when he described the diffuse nebulosity of M42. In following years, the nebula was referenced by Johann Baptist Cysat, Galileo Galilei, and Christiaan Huygens. It was the subject for the first instance of astrophotography regarding a nebula, taken by Henry Draper in 1880. Later, spectroscopic data revealed the diffuse nature of the gas, and its kinematic properties.
The nebula itself has been an object of intense research throughout the years. M42 exhibits all three kinds of nebula: emission, reflection, and dark. By this, I mean that different regions of the nebula interact with the starlight in different ways. Emission nebulae are the result of ionising radiation tearing the electrons from their host nucleus and then re-combining to produce a the characteristic red colour which Hydrogen is known for. Reflection nebulae are the result of scattering by blue light off of the dust and gas. And dark nebulae are patches of dust and gas so thick that no light penetrates them, and can only be seen in contrast. They are usually the opposing side of a reflection nebula. These nebulae point to M42 as the site for ongoing star formation, known as a stellar nursery. By using special techniques, telescopes are able to see into the dust and gas to peer into the lives of young stars.
If you’ve made it this far, then you’ve earned your view of M42. But unfortunately, you are going to have to wait a few months before Orion becomes readily visible - nearer to springtime!
Top: Constellation Orion - Skatebiker on Wikipedia
Top Middle: Colour Orion - NASA/ESA
Bottom Middle: Drapper’s Orion - Henry Draper
Bottom: Young Stars - Rice University/NASA