The Lagoon and The Trifid, August 26, 2008. The magenta cloud in the centre of this photograph is the Lagoon Nebula, also known by its Messier number, M8. This immense cloud of hydrogen gas is visible to the naked eye as a hazy patch of light near the centre of the Milky Way, in the constellation Sagittarius. In binoculars or a telescope it is a magnificent and memorable object to study. A cluster of young stars inside M8 heat the nebula with their radiation causing it to glow. The Lagoon Nebula is located about 5,200 light years away.
To the upper right of M8 is the Trifid Nebula, also known as M20. It is about the same distance from Earth as M8, and also glows magenta as an emission nebula. It also has a conspicuous blue reflection nebula component. Opaque dark nebulae made up of cold dust clouds float in front of M8 and M20 giving them a mottled look.
There is a third Messier object in the photograph, M21. It is an open cluster stars above M20. This open cluster of about 60 stars is thought to be made up of very young stars, possibly only about five million years old.
The dense concentration of stars to the lower left are in line with the centre of our galaxy, which is located roughly 26,000 light years away.
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