Sagittarius Star Cloud
About 2 ° × 1 °
About 10000-15000 Lj
June 20, 1764
M24 • IC 4715
Messier 24 is a visible part of the Sagittarius spiral arm of the Milky Way. After the appearance of the star cloud coined Angelo Secchi (Vatican Observatory ) in 1850 the name Delle Caustiche. Today it is usually called the Sagittarius cloud or small Sagittarius Cloud - the delineation of the large Sagittarius Cloud, a visible part of the central region of the galaxy a little further south.
While the central and all the distant parts of the galaxy obscured by interstellar dust and thus are not visible to the human eye, allowing here a window in the dust distribution to look at a section near the galactic center. Normally, swallowed the dust 20-30 brightness levels of light. In this sense, the object Messier 24 can be regarded as a region of the sky with little absorption or interstellar dust.
The area is located in the constellation Sagittarius and has an apparent extension of about 2 ° × 1 °. The star cloud is about 10 000 light- years away. It contains several open clusters, in particular NGC 6603 stands out. Further, among others, the two dark clouds Barnard 92 and Barnard 93 are distinctly in the light of Sagittarius cloud.
The object was observed by Charles Messier in 1764 and incorporated under the number 24 in his catalog. Sometimes Messier 24 is also identified with NGC 6603; due to its description of the object ( in particular its dimensions ), it is no doubt that Messier has observed and described the star cloud and not only these star clusters.
Edward Barnard was around 1915 photographically prove two dark nebulae, which form the northern edge of the " sight tube ": Barnard 92 (also called black hole ) and Barnard 93 They are considerably larger than the usually take about 25 light years large " flakes " of interstellar dust.