The Tilted Earth at Its ‘Equal Night of Spring’
By NATALIE ANGIER
Published: March 20, 2007
“For many cultures throughout history, people got ready to start tilling the fields. Ancient peoples may not have understood orbital mechanics, but they were tireless observers of the Sun, stars and planets and noted with enviable precision how the position of the sunrise shifted on the horizon throughout the year. By tracking solar motions, they kept track of time and could estimate with some security when the last frost had passed and it was safe to plant crops.
“It seems wonderfully appropriate that you would anchor the timing of your planting season directly to the source of it,” said Dr. Paul Doherty, a physicist and senior staff scientist at the Exploratorium museum in San Francisco.
Archaeological evidence abounds that astronomy is among the oldest of professions, and that people attended with particular zeal to the equinoxes and the solstices. The Great Sphinx of Egypt, for example, built some 4,500 years ago, is positioned to face toward the rising sun on the vernal equinox.
In the 1,500-year-old Mayan city of Chichén Itzá, in Mexico’s Yucatán peninsula, the magnificent Kukulcán Pyramid practically slithers to life each spring equinox evening, as the waning sun casts a shadow along its steps of seven perfectly symmetrical isosceles triangles, a pattern suggesting the diamondback skin of a snake.
“The snake’s head points north, to the sacred part of the site, and the snake’s body represents a kind of umbilicus between sky and earth,” said Dr. Isabel Hawkins, an astronomer at the University of California, Berkeley, who has traveled to the site to witness the alignment, as do about 60,000 people from around the world every March.
“It’s a truly international celebration of the equinox,” she said. “It gives you goose bumps to be part of it, and to share with a bunch of strangers an intimate, primal sense of your connection to the bigger universe.””