M 45 is located in the constellation Taurus, in the Orion Arm of our home Galaxy.  It is 440 Light Years away from earth towards the outer edge of the Milky Way. It is an open star cluster with 7 huge intensely bright blue stars along with hundreds of others.  These hot blue stars are so bright they light up the dust cloud currently passing through, illuminating this dust in a reflection of blue light.  To further illustrate how bright these stars are you can see them with the naked eye even though they are 2,586 TRILLION miles from earth (440 x 5.878 trillion).  With binoculars they are even more brilliant, although you cannot see the dust without long exposure photography.

The cluster is dominated by hot blue and luminous stars that have formed within the last 100 million years. Reflection nebulae 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 stars are currently passing.

The Pleiades are a prominent sight in winter in the Northern Hemisphere, and are easily visible out to mid-Southern latitudes. They have been known since antiquity to cultures all around the world.  The star cluster was born when dinosaurs still roamed the Earth, about one hundred million years ago. It is significantly younger than our 5-billion-year-old solar system. 

The earliest-known depiction of the Pleiades is likely a Northern German Bronze Age artifact known as the Nebra sky disk, dated to approximately 1600 BC. 

The Babylonian star catalogues name the Pleiades MULMUL, meaning "stars" (literally "star star"), and they head the list of stars along the ecliptic, reflecting the fact that they were close to the point of vernal equinox around the 23rd century BC. 

The Ancient Egyptians may have used the names "Followers" and "Ennead" in the prognosis texts of the Calendar of Lucky and Unlucky Days of papyrus Cairo. 

Some Greek astronomers considered them to be a distinct constellation, and they are mentioned by Hesiod's Works and Days, Homer's Iliad and Odyssey, and the Geoponica. 

The Pleiades was the most well-known star among pre-Islamic Arabs and so often simply referred to as "the Star" (al Najm). Some scholars of Islam suggested that the Pleiades (ath-thurayya) are the "star" mentioned in Surah An-Najm ("The Star") in the Quran.

In Japan, the cluster is mentioned under the name Mutsuraboshi ("six stars") in the 8th-century Kojiki.  The cluster is now known in Japan as Subaru.  It was chosen as the name of the Subaru Telescope which is the 8.2-meter (320 in) flagship telescope of the National Astronomical Observatory of Japan.  It is located at the Mauna Kea Observatory on the island of Hawaii. It had the largest monolithic primary mirror in the world from its commissioning in 1998 until 2005.  It was chosen as the brand name of Subaru automobiles to reflect the origins of the firm as the joining of five companies, and is depicted in the firm's six-star logo.

The Sisters - Asterope/Sterope II; Taygeta; Maia (Nebula NGC 1432); Celaeno; Alcyone; Electra; Merope (Nebula NGC 1435)

With larger amateur telescopes, the nebulosity around some of the stars can be easily seen; especially when long-exposure photographs are taken. Under ideal observing conditions, some hint of nebulosity around the cluster may even be seen with small telescopes or average binoculars. It is a reflection nebula, caused by dust reflecting the blue light of the hot, young stars.

It was formerly thought that the dust was left over from the formation of the cluster, but at the age of about 100 million years generally accepted for the cluster, almost all the dust originally present would have been dispersed by radiation pressure. Instead, it seems that the cluster is simply passing through a particularly dusty region of the interstellar medium.

Studies show that the dust responsible for the nebulosity is not uniformly distributed, but is concentrated mainly in two layers along the line of sight to the cluster. These layers may have been formed by deceleration due to radiation pressure as the dust has moved towards the stars.