Mar 20, 2024
M73 // Gary Imm
Another oddity in the Messier catalog, M73 is the four stars at the center of the image. Messier discovered this "object" in 1780 and thought it was a sparse open cluster. This idea was held until 2002 when better data for these four stars was collected and it was determined that these stars are unrelated to each other. Their arrangement on the sky is termed an asterism.
Data from the Gaia spacecraft show that the stars are 1,030, 1,250, 2,170, and 2,290 light years from Earth and thus completely unrelated.