further analysis of asterisms is still important for the identification of sparsely populated open clusters. A full study of very many such clusters would demonstrate how, how often, and to what degree open clusters are ripped apart by the gravitational forces in the Milky Way and reveal more of the sources of these forces. Location See also List of Messier objects Messier 40 - a double star included in the Messier catalogue that was also mistakenly identified as having nebulosity Notes and references External links SEDS: Messier Object 73 Messier 73, LRGB CCD image based on two-hours total exposure Messier 073 Messier 073 073 Messier 073 Orion–Cygnus Arm Astronomical objects discovered in 1780