March 20, 2005
Exploring the Sun Through Ancient Civilizations
NASA -- What do Stonehenge, Mayan pyramids, and a spacecraft a million miles away have in common? They're linked by a human need to explore and understand the Sun, moon, planets, and stars.
This year's Sun-Earth Day on March 20 focuses on "Ancient Observatories: Timeless Knowledge" and falls on the vernal equinox when day and night are the same length. Appropriately, NASA and the Exploratorium in San Francisco are focusing on ancient peoples and their fascination with the Sun, which played a major role in most Native American religious practices and social events.
NASA continues to pay close attention to the Sun today through ground and satellite-based observatories, still seeking to understand this star as a dominant influence on our lives. The Sun seems to have a major role not only in religious practices of indigenous people, but also art, culture, and more.
For example, the Mayans built the Pyramid of Kulkulkan in El Castillo, Mexico between 1000 and 1200 A.D. with the Sun's movement in mind. Located in the ruins of Chichen Itza, this 75 foot-tall, squared based pyramid is unique among all known pyramids worldwide for its central role in a dramatic shadow and light display during the spring and fall equinoxes.
The axes that run through the northwest and southwest corners of the pyramid are oriented toward the rising point of the Sun at the summer solstice and its setting point at the winter solstice. Kukulcan is the Mayan name for the Feathered Serpent God (also known as Quetzalcoatl to the Aztecs).
In Chaco Canyon, located in the Chaco Culture National Historic Park, N.M., several structures indicate the ancient culture's understanding of the Sun's movements. Pueblo Bonito's special corner windows let sunlight through, but only as time marches onwards to the winter or summer solstice.
At Casa Rinconada, a window on the south wall lets a beam of light shine into a niche on the back wall at the time of the summer solstice. Fajada Bute projects a dazzling "Sun Dagger," where during equinoxes and solstices, one or sometimes two, thin slivers of light frame a spiral petroglyph.
Across the globe to ancient Egyptians, the Sun God Ra was the most universally worshipped king of the gods and all-father of creation. He commanded a chariot that rode across the sky during the day. The magnificent temple at Karnak celebrates Ra through its enormous pillars, designed in harmony with the Sun and stars over a span of nearly 2000 years.
We may never know for certain just how these solar-inspired structures were used. There also remains some controversy about their exact details and the actual intent of their creators. But we can at least admire their creators for what must have been a sophisticated understanding of the Sun's movements. We can also admire them for their cleverness in applying this knowledge to enhance their own survival in a largely unforgiving environment.
The purpose of Sun-Earth Day is to get people to understand that the Sun is a magnetic star that impacts the Earth and other planets in our solar system, and that humans of all cultures and times have and will use technology to understand the Sun and the Universe beyond.
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