NGC 6910 - an open star cluster with the shape of a giraffe
NGC 6910 is a wonderful open star cluster in the constellation Swan, which was discovered by F.W. Herschel in 1786.
It is located 3,700 light-years from Earth and therefore lies behind the so-called "Great Rift". This is the name given to the large dark
cloud that divides the Milky Way in the constellation of Swan and contains up to one million solar masses of plasma and dust.
NGC 6910 is a very small and relatively star-poor open cluster. The core radius is only 3 light-years - this is the size of the region from
which 50% of the emitted light originates. In the central part of the cluster there are a little more than 100 stars. The brightest star is a
blue super giant of spectral class B2 with an absolute brightness of -3.3mag - so it shines nearly 2,000x as bright as our Sun. Its surface
temperature is more than 25,000 Kelvin.
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Finding the cluster is quite easy, because it lies only half a degree northeast of Gamma Cygni, the middle star of the constellation Swan.
I found the sight most beautiful at magnifications of 200x to 270x, because not only the brighter cluster stars, but also many more faint
stars are visible. In total I could count about 40-50 stars, which are all different in brightness.
Especially great is the shape of the cluster, which reminds me very much of a giraffe. In the English-speaking world, NGC 6910 is called
the "Rocking Horse Cluster". This is also a fitting name, but I still think that the proportions are a bit more like a giraffe. But everyone
can make up his own mind - best on a warm summer evening when looking through one's own telescope.
