The Seven Sisters at Halloween

When Have You Last Gazed at the Pleiades?

January 29, 2019
Pleiades Star Cluster
Antonio Fernandez-Sanchez/NASA

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It’s an annual autumn ritual: The reappearance of the glorious Seven Sisters. During Halloween week, they always rises in the east before 7 PM and are nicely up after 8 PM. Learn more about the Pleiades—and their connection to All Hallows’ Eve.

The Pleiades is a tightly packed cluster of stars. There’s nothing else like it. No obstetrician attended the birth of the Pleiades, 60 million years ago. As these fiercely hot suns awakened from the dazzling and dangerous gaseous nursery, the newborn stars materialized like a distant sunrise in the skies of Earth 400 light years away.

History of the Pleiades

They seem harmless. But that wasn’t always the case. In ancient times, the Pleiades had a strange, sinister reputation. Such medieval rituals as the pagan Black Sabbath and All Hallow’s Eve (which evolved into our own Halloween) were set to occur when the Pleiades reached their highest point at midnight. 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. Some believe they may be linked to the Atlantis myth, itself perhaps a legend evolved from the awesome eruption of the Santorini Volcano in 1450 BC that devastated the Minoan civilization on nearby Crete.        

The Pleiades had an odd importance to civilizations throughout time and around the world. In Egypt, they were revered as one of the forms of the goddess Isis. In ancient Persia, the date in which they reached their highest midnight ascendancy was marked with ceremony. In Mayan and Aztec culture, this same yearly occasion had a forbidding undertone, and was given tremendous importance—with at least one city’s streets and pyramid aligned with the setting of the Pleiades.

Stars of Subaru

In Japan, the star cluster’s ancient name is Subaru. Until very recently, the six companies that merged to produce automobiles in 1953 placed a crude star map of the Pleiades on each of their cars. Over the years, its single brighter star has been portrayed as ever-more luminous and increasingly separated from the others, perhaps revealing some sort of corporate infighting.

But why seven sisters? That’s the real mystery. After all, normal eyesight readily sees only six, the same number found on the Subaru insignia.

If you can see a seventh, then you should be able to see an eighth as well. How many you can perceive tells as much about the purity of your sky as the state of your vision. With good eyes in a rural setting, nine are a cinch, and even eleven aren’t impossible.

subaru-symbol_full_width.jpg

The Lost Seventh Sister

Why have civilizations as disparate as the ancient Greeks, Australian aborigines, and Japanese all possessed legends of the “lost Pleiad” which have persisted through the centuries? Even two thousand years ago, a Greek poet wrote:

           “…their number seven, though the myths often say…that one has passed away.”         

One clue is that, as binoculars reveal, they’re blue—a color that indicates stellar youth. Young, hot, giant stars are often unstable, gobbling up their nuclear fuel in an adolescent frenzy that frequently produces instability.

They’re in their infancy even today: our own sun has been around 250 times longer. The dinosaurs gazed unconcernedly into a sky empty of the Sisters, which sprang into view just before we ourselves did. So maybe one of these newborns lost a bit of its light. In any case,  since all massive stars die young, the Pleiades will be long gone when most of the galaxy’s stars are still enjoying middle age. Toddling gracefully across November’s chilly skies —and very much linked with Halloween—the newborn sisters are only for now.

What’s the Moon phase this Halloween? Check out our Moon Phase Calendar to find out!

About This Blog

Welcome to “This Week’s Amazing Sky,” the Almanac’s hub for everything stargazing and astronomy. Bob Berman, longtime and famous astronomer for The Old Farmer’s Almanac, will help bring alive the wonders of our universe. From the beautiful stars and planets to magical auroras and eclipses, he covers everything under the Sun (and Moon)! Bob, the world’s mostly widely read astronomer, also has a new weekly podcast, Astounding Universe