Spring is a great time to get outside and observe the natural world in all its glory.
Flowers are blooming, insects are humming and animals are waking from long winter naps. With the miracle of life occurring all around us, it is easy to overlook the subtler natural phenomena taking place this season.
During April, one of the best-known celestial objects is visible in the evening sky. The Pleiades, an easily discernable cluster of stars, can be seen setting in the west just after sunset. The Pleiades is located near the ecliptic, and consequently, the seasons can be marked by its heliacal rising and setting.
In short, a heliacal rising occurs when a celestial body becomes visible over the eastern horizon at dawn after a period of time when it could not be seen, either because it was below the horizon, or just above the horizon but masked by the light of the sun. Therefore, the Pleiades was used in ancient times to signify important dates on the calendar and the changing of seasons.
In the Northern Hemisphere, the heliacal setting of the Pleiades in April signaled the beginning of the growing season. Because the star cluster is not visible again until June, when it appears just before dawn, it also was used by many cultures as a midsummer marker. Finally, in November the Pleiades rises after sunset, thus marking the end of the growing season. The Pleiadean calendar is the oldest known star-based calendar, used across the globe for thousands of years to mark the changing seasons.
The Pleiades was not only one of the most useful heavenly bodies to ancient societies, it was also one of the most romanticized. The ancient Greeks, who gave us the name "Pleiades," believed that the stars represented the seven daughters of Atlas, or seven sisters (six of the stars are visible to the naked eye, while the seventh is much harder to see). The sisters were put in the sky by Zeus to protect them from an overzealous suitor, Orion, as well as to keep their father company while he held up the sky.
There are many other stories about the Pleiades told around the world, and here are a few of my favorites: In Norse mythology, the stars represented hens belonging to the goddess Freya. The Kiowa tribe, like the Greeks, believed the stars were seven maidens placed in the sky by the Great Spirit to save them from giant bears. Finally, ancient Celts associated the appearance of the Pleiades in November with All Hallows Day, and saw the stars as tears, representing mourning and the dead.
Like last month, I will conclude my article with the immortal words of Tennyson. I believe he captured the beauty of the Pleiades perfectly when he wrote, "Many a night I saw the Pleiads, rising thro' the mellow shade/Glitter like a swarm of fireflies tangled in a silver braid."
gretchen@DurangoNatureStudies.org or 382-9244. Gretchen Lamar is program manager for Durango Nature Studies.