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The Engraved Hourglass Nebula (also known as MyCn 18) is a young planetary nebula in the southern constellation Musca about 8,000 light-years from Earth. It was discovered by Annie Jump Cannon and Margaret W. Mayall during their work on an extended Henry Draper Catalogue (the catalogue was built between 1918 and 1924).
The nebula lies in the Perseus Arm of the Milky Way galaxy, at a distance of about 2.0 kiloparsecs (6,500 ly) from Earth. It has a diameter of 3.4 parsecs (11 ly), corresponding to an apparent diameter of some 7 arcminutes, and is expanding at a rate of about 1,500 kilometres per second (930 mi/s), or 0.5% c.he Crab Nebula currently is expanding outward at about 1,500 km/s (930 mi/s). Images taken several years apart reveal the slow expansion of the nebula, and by comparing this angular expansion with its spectroscopically determined expansion velocity, the nebula's distance can be estimated.