Planetary Nebulae Symposium - Introductory Remarks

Extract

It seems proper to start our Symposium from the very beginning. The oldest known discovery of a planetary nebula dates back to Messier who in 1764 catalogued the Dumbbell nebula, NGC 6853, as Messier 27. Only 100 years later Huggins discovered the emission line spectra of planetary nebulae and he pointed out that his discovery proves that these objects are not clusters of stars but are “enormous masses of luminous gas or vapor”. In 1887, a curious suggestion was made by Lockyer who thought that the nebulae were clusters of burning meteorites when he incorrectly identified three nebular emission lines with magnesium.