November is the Only Month You Can View the Pleiades with Your Naked Eye

The spooky Seven Sisters stars reappeared in the night sky on Halloween and will shine brightest on November 21.

EarthSky contributer Greg Hogan captured this image of the Pleiades in November 2015.

The glorious reappearance of the Pleiades happens every year around Halloween. The stars known as the Seven Sisters light up the night sky for the entire month of November, the only month they can be seen clearly with the naked eye.

The Pleiades star cluster culminates – reaches its highest point in the sky –  on or around November 21 each year, at midnight.

Although the midnight culmination date for the Pleiades advances over the long course of time, the date of Halloween has remained fixed by tradition.

In ancient times, the Pleiades had a dark, sinister reputation.

“Medieval rituals as the pagan Black Sabbath and All Hallow’s Eve were set to occur when the Pleiades reached their highest point at midnight,” says The Old Farmer’s Almanac.  “Some have speculated that the rituals could have originated as a sort of commemoration of some ancient catastrophe that resulted in great loss of life.”

For example, some believe the star system is related to the myth of the lost city of Atlantis, a legend that may have evolved from the awesome eruption of the Santorini Volcano in 1450 BC that devastated the Minoan civilization on nearby Crete.

The Pleiades have been significant to many civilizations throughout history.

The ancient Egyptians believed they were one of the forms of the goddess Isis. The Persians celebrated their culmination at midnight. The Mayans and Aztecs aligned their city streets and pyramids with the setting of the Pleiades, an event with an ominous undertone. The ancient Japanese named the star cluster Subaru, which the car company is named after and it’s logo designed for.

Despite the Seven Sisters name, only six bright stars can be easily spotted. Many disparate civilizations – including the Greeks, Australian aborigines, and Japanese – possess legends of the “lost Pleiad.”

Two thousand years ago, a Greek poet wrote: “…their number seven, though the myths often say…that one has passed away.”

One theory is that because the stars are young, hot and giant, they “gobble up their nuclear fuel in an adolescent frenzy that frequently produces instability,” the Almanac says. “All massive stars die young.”

The remaining 6 sisters will be long gone when most of the galaxy’s stars are still enjoying middle age.