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The Engraved Hourglass Nebula 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 . At the time, it was designated simply as a small faint planetary nebula. Much improved telescopes and imaging techniques allowed the hourglass shape of the nebula to be discovered by Raghvendra Sahai and John Trauger of the Jet Propulsion Laboratory on January 18, 1996. It is conjectured that MyCn 18's hourglass shape is produced by the expansion of a fast stellar wind within a slowly expanding cloud which is denser near its equator than its poles. The vivid colours given off by the nebula are the result of different 'shells' of elements being expelled from the dying star, in this case helium, nitrogen, oxygen and carbon.

Hourglass Nebula
Nebula
MyCn18-crop.png
Hubble Space Telescope image of the Hourglass Nebula
Observation data: J2000 epoch
Right ascension 13 39 35.116
Declination −67° 22′ 51.45″
Distance 8 kly (2.5 kpcly
Apparent magnitude 13.0
Constellation Musca
Physical characteristics
Radius - ly
Absolute magnitude -
Notable features -
Designations

ESO 97-1,
Engraved Hourglass Nebula,
Etched Hourglass Nebula,

PN MyCn 18
See also: Lists of nebulae

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). At the time, it was designated simply as a small faint planetary nebula. Much improved telescopes and imaging techniques allowed the hourglass shape of the nebula to be discovered by Raghvendra Sahai and John Trauger of the Jet Propulsion Laboratory on January 18, 1996. It is conjectured that MyCn 18's hourglass shape is produced by the expansion of a fast stellar wind within a slowly expanding cloud which is denser near its equator than its poles. The vivid colours given off by the nebula are the result of different 'shells' of elements being expelled from the dying star, in this case helium, nitrogen, oxygen and carbon.

The Hourglass Nebula was photographed by the Wide Field and Planetary Camera 2 of the Hubble Space Telescope.

A less-famous "Hourglass Nebula" is located inside the Lagoon Nebula.