M27: Not A Comet . ... Well, 20th century astronomers would classify it as a Planetary Nebula ... but it's not a planet either, even though it may appear round and planet-like in a small telescope. Messier 27 (M27) is now known to be an excellent example of a gaseous emission nebula created as a sun-like star runs out of nuclear fuel in its core. ... NASA Web Site Statements, Warnings, and Disclaimers . NASA Official: Jay Norris. ... A service of: LHEA at NASA / GSFC . ...