A 9th-magnitude planetary nebula about 2000 l.y. away in Lyra, also known as M57 or NGC 6720. The hot 15th-magnitude central star is surrounded by a shell of luminous gas and dust some three-quarters of a light year in diameter. In small telescopes the shell looks like an elliptical smoke ring 70″ × 150″ across. The ring is expanding at 19 km/s. Observations by the Hubble Space Telescope have demonstrated that the ‘ring’ is in fact a cylinder of gas aligned end on to us.
http://hubblesite.org/image/748/news_release/1999-01
- molecular vibrations
- molecular volume
- molecular weight
- molecule
- mole drain
- mole fraction
- molfile format
- Molina, Luis de (1535–1600)
- Molina, Mario José
- Molinism
- Molisch’s test
- mollic horizon
- Mollier chart
- mollisols
- Mollusca
- molluscs
- Molly Maguires
- Molonglo Radio Observatory
- Molotov, Vyacheslav (1890–1986)
- molten salt
- molybdenite
- molybdenum
- Molyneux’s problem
- MOM
- moment