Thursday 24 November 2011

The Lagoon and The Trifid Nebulae

Four 5 minute exposures of a favourite region of sky of astronomers was enough to produce this wonderfully colourful and stunning scene. The Lagoon nebula (Messier 8) is below centre, and you can see red hydrogen gas extending out to the left of it. Around that is a dark, twisty channel, with some strange tight turns. That is in turn blocking out the light from the myriad stars of the central milky way in the background. A short hop celestially north lies the trifid nebula (M20), which shows its beautiful colour contrast, and the star cluster M21 appears above that. The darkness to the right is merely apparent due to the blocking of star light by tiny aggregations of molecules, spread thinly, but over such a large volume they collectively cut out virtually all what we see. Other wavelengths of radiation, such as infra red, can shine through these clouds. The 'visible' wavelengths between 0.4 and 0.7 μm were captured with a Canon 1000D with the nearIR-red filter removed, through a Sigma telephoto zoom lens at focal length ~ 300mm, on a well aligned Astrotrak.

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