A guide to what's up in the sky for Southern Australia

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The Swan Nebula (29th Jul 2024)

M17 – The Swan Nebula in Sagittarius

M17 is a region of ionised interstellar atomic hydrogen. It was discovered by Philippe Loys de Chéseaux in 1745. Charles Messier catalogued it in 1764. It is located amongst some of the richest starfields of the Milky Way in northern Sagittarius.

M17 is between 5,000 and 6,000 light-years from Earth, and it spans some 15 light-years in diameter. The cloud of interstellar matter of which this nebula is a part is roughly 40 light-years in diameter and has a mass of 30,000 solar masses. It is considered one of the brightest and most massive star-forming regions of our galaxy. Its local geometry is similar to the Orion Nebula except that it is viewed edge-on rather than face-on.