Pleiades << PLEE uh deez >> are a bright star cluster visible in the night sky. Star clusters are gravitationally bound groups of stars that move through the galaxy together. Also known as “The Seven Sisters,” the cluster actually consists of over 1,000 stars. Most people count 6 hot, bright stars, but if the sky is dark enough, some people with sharp eyesight can spot 7 to 14 stars. A small telescope reveals hundreds more.
In the mid-1700’s, the French astronomer Charles Messier created a catalog of “fuzzy blurs that are not comets” to aid the astronomers of the time who were seeking to identify new comets. The Pleiades are formally known as Messier Object 45 or simply M45 in this catalog. The star cluster is located about 430 light-years from Earth. One light-year equals the distance light travels in a vacuum in a year, about 5.88 trillion miles (9.46 trillion kilometers). Astronomers believe that the hot stars of the Pleiades first formed as a group about 115 million years ago. The stars are slowly drifting apart due to gravitational tugs from other stars. It will take about 250 million years for the stars to disperse to where they will no longer form a star cluster.
The Pleiades can be seen in the region of the sky defined as the constellation Taurus. The seven brightest stars represent the seven daughters of Atlas and Pleione of Greek mythology. The stars are named Alcyone, Asterope, Celaeno, Electra, Maia, Merope, and Taygeta. The reddish star Aldebaran, the brightest star in the constellation Taurus, appears to follow the Pleiades through the night sky. Aldebaran translates from Arabic as “The Follower.” The mythology of the Aboriginal peoples of Australia has the seven sisters pursued by a powerful warrior, seen among stars that rise behind them. The Japanese call the star cluster “Subaru,” which means “united.” The seven stars inspired the logo for Subaru, the automobile manufacturing division of the Japanese transportation company Fuji Heavy Industries.
The Pleiades were used to mark important events on the calendars of many cultures. Among the Zuni people of the American Southwest, the name for this star cluster means “seed stars.” The disappearance of the star cluster from the night sky signals the beginning of the planting season. The Druids—the learned, priestly class among the ancient Celts—celebrated the festival of Samhain around the time the Pleiades reach their highest point in the night sky. Among the Druids, Samhain was a magical time of transition. Halloween developed from this festival.
