M20 – The Trifid Nebula
Sketch by Kiminori Ikebe
Mr. Ikebe observed and sketched this view of M20 using a 50 cm Dobsonian at 220X.
M20, The Trifid Nebula, is a famous and beautiful target for astrophotographers and visual observers alike. The red emission nebula contains a young star cluster at its center, and is surrounded by a blue reflection nebula that is most noticeable at the northern end. It’s distance is not well agreed upon, and is listed anywhere from 2,200 light years (Mallas/Kreimer) to 9000 light years (Jeff Hester). Its magnitude estimate is also wide, and is listed from 9.0 (Kenneth Glyn Jones) to 6.8 (Machholz). Part of the magnitude difficulty comes from the very bright triple-star system at the heart of the nebula.
The dark nebula that crosses the Trifid was cataloged by Barnard and listed as B 85. The object was originally cataloged by Charles Messier in 1764, when he described it as a cluster of stars.