ASTRO:
     type=open star cluster
     const=Taurus
     magnitude=1.20
     dist ~ 444 ly
​     size ~ 16 ly
IMAGE:
     location=EB Backyard
     BrtlCls=4
     exposure=DSLR OSC: 51x120s (1.7h),  ISO1600
EQUIPMENT:
​     optics=ES102CF APO / Stellarvue 0.8x rdcr, FL(eff.)=571mm, f(eff.)/5.6
     camera=Nikon D90 (stk)
     filter=(none)
     mount=Celestron AVX EQ
     guiding=Orion 60x240mm, ZWO ASi224MC
SOFTWARE:
     acquisition=APT, PHD2, Stellarium
     processing=PixInsight, Photoshop, LrC

The Pleiades, also known as "The Seven Sisters", stands as one of the most well-known, and common objects found in the skies of the northern hemisphere.  It is also known by many other names assigned to it by past and present cultures from around the world.  Listed in Charles Messier's catalog of non-comet-like objects as M45, it's stars make-up a small asterism and open star cluster containing middle-aged, hot, blue, type B stars in the north-west area of the constellation Taurus (the "Bull").  At a distance of about 444 light years, it is among the closest star clusters to Earth; and, it IS the nearest Messier object to Earth.  Due to its extreme brightness, it is the most obvious star cluster to the naked eye in the northern night sky.

The cluster is dominated by hot, blue, luminous stars that have formed within the last 100 million years or so (...being a short period of time by astronomical standards).  Reflection nebulae clouds around the brightest stars were once thought to be left over material from their formation, but are now considered likely to be an unrelated dust cloud in the interstellar medium through which the cluster is currently passing.  The stars are estimated to be moving at a speed of 18 km/s with respect to the clouds.

Computer simulations have shown the Pleiades were probably formed from a compact configuration that resembled the Orion Nebula.  The stars in the cluster are moving through space together as a group, all in the same direction; but, they are not gravitationally bound together (like those of a globular cluster).  Astronomers estimate the cluster will survive for about another 250 million years, after which it will disperse due to gravitational pulling the individual stars in different directions as they pass near-by other objects in the Milky Way galaxy.

One of the claimed sources of the name "Seven Sisters" comes from the fact that most naked-eye observers are able to count appx 7 of the brightest stars in the formation.  (Some may count more, some less - depending on how "good" their eye-sight is.)  Astronomers have actually accounted for 96 stars in the cluster.

Our global culture today is replete with examples of corporations and other commercial interests seeking to identify themselves through logo's, emblems and symbols derived from objects found in our nighttime sky; and, the Pleiades resides near the top of the list.   As one of the best examples of this, six (6) of this object's stars, in their tightest formation near the top of this image, are used today by Subaru Corporation as its logo both corporately and on their cars.   Other widely known and easily recognizable corporate emblems with their origins tied to skyward starscapes and constellations  include Pegasus, the "Flying Horse" (formerly, Mobil Oil Company), and Sirius the "Dog" (Sirius XM Radio), among many others.

201115 - M45 "Pleiades" open star cluster ("The 7 Sisters")