The Pleiades (M45) 

The Pleiades: The Seven Sisters of the Night Sky

Known as the Seven Sisters and officially designated as Messier 45 (M45), the Pleiades is perhaps the most recognizable star cluster in the entire heavens. Located in the constellation Taurus, this sparkling group of blue stars has been guided by sailors, farmers, and astronomers for thousands of years.

Unlike the Rosette or the Orion Nebula, the Pleiades is an Open Star Cluster, representing a family of stars born together from the same cloud of gas.

A Cosmic Eye Test

For centuries, the Pleiades has served as a natural vision test. While most people can see six stars with the naked eye under average conditions, those with excellent eyesight or very dark skies can spot seven, eight, or even up to twelve.

• The Paradox: Despite being called the "Seven Sisters," there are actually over 1,000 stars in the cluster, most of which are too faint to see without a telescope.

• The "Lost Sister": Many cultures have legends about a "lost" seventh sister, which astronomers believe may be due to the star Pleione—a shell star that varies in brightness and may have been more visible in antiquity.

The "Blue Veil" Reflection Nebula

In long-exposure photographs, the Pleiades appear to be swimming in a ghostly blue mist.

• Reflection Nebula: This is not gas left over from their birth. Instead, the cluster is currently passing through a particularly dusty region of the Milky Way.

• The Blue Glow: The hot, blue stars reflect their light off the dust particles. Because blue light scatters more easily than red light (the same reason our sky is blue), the nebula glows with a striking sapphire hue.

The Subaru Connection

If you’ve ever looked at the logo of a Subaru vehicle, you’ve seen the Pleiades!

• "Subaru" is the Japanese name for the Pleiades, meaning "united" or "gathered together."

• The logo features six stars because that is the number typically visible to the naked eye. The company chose this name to represent the merger of five companies into one larger entity (Fuji Heavy Industries).

Young, Hot, and Short-Lived

The stars of the Pleiades are cosmic toddlers, estimated to be only about 100 million years old.

• The Future: They won't stay together forever. Because open clusters are loosely bound by gravity, the Pleiades will eventually drift apart. In about 250 million years, the sisters will have wandered so far from each other that they will simply be individual stars scattered throughout the galaxy.