Messier 45
Object Information:

Messier 45 - The Pleiades Star Cluster

Also known as the Pleiades star cluster and "the Seven Sisters";
Type - Bright open cluster associated with a reflection nebulae;
Constellation - Taurus;
Distance - 410 light years;
Size - The dipper shaped asterism comprised of the cluster's brightest members is about 7 light years across. The entire open cluster spans as much as 20 light years.

This bright open cluster is perhaps one of the best known objects in the skies. Under ideal visual observing conditions nine stars can be seen in the dipper shaped asterism at the center of the cluster. However, there are nearly 300 (mostly faint) confirmed Pleiades members. The blue color is star light reflecting from a dust cloud that the cluster just happens to be moving through. Burnham's Celestial Handbook reports that the Pleiades group is one of the nearest open or "galactic" star clusters. The nine brightest members are concentrated in a region approximately 7 light years in diameter. All of the brightest members are "B" type stars. Eta Tauri, also known as Alcyone, is the brightest member of the cluster and is nearly 1000 times more luminous than the Sun. It is also estimated to be 10 times more massive than the Sun. This star cluster has had a prominent role in the mythology of many cultures. An interesting treatment of this history and mythology can be found in Burnham's Celestial Handbook.

Image date:

September 17, 2009

Exposure Information:

RGB image - 48 minutes per color channel

Imaged at:

Mt. Laguna, Cleveland National Forest, San Diego County, California


Optics - Takahasi Eplison 160 astrograph at f/3.3
Mount - Astro-Physics AP 1200 GTO
Camera - SBIG STL-11000M