Roden Crater belongs to a tradition of monumental structures that have been built by artists, rulers and priests, ancient and modern. Above-ground observatories for specific celestial events include Maes Howe in Scotland (which predates the pyramids), Newgrange in Ireland, and Abu Simbal in Egypt. Remnants of ancient sites that resemble ‘handmade volconoes,’ large mounds with a depression at the summit, are also scattered around the world. These include Herodium near Jerusalem and Old Sarum in England. In the sixteenth century, the great astronomer Tycho Brahe pioneered ‘naked eye observatories,’ of which the eighteenth-century Jantar Mantar in Jaipur is perhaps the best example. Turrell studied and adapted essential features of the naked-eye observatory in his designs for Roden Crater, where the natural formation recalled these man-made precedents.
Throughout the planning and construction of Roden Crater, Turrell consulted with noted astronomers including E.C. Krupp, Director of the Griffith Observatory in Los Angeles, and the late Richard Walker, an astronomer with the U.S. Naval Observatory in Flagstaff, in order to calculate the excavation and alignment of the Crater’s tunnels and apertures. When completed the structures within the Crater will form a vast naked eye observatory for celestial objects and events ranging from obscure and infrequent to the more familiar summer and winter solstice.
The East Portal, the Alpha (East) Tunnel and the Sun | Moon Chamber act in concert as a monumental Camera Obscura, or pinhole camera. Transmitting light from the East Portal aperture, the Alpha (East) Tunnel focuses images on the west side of the monumental image stone in the Sun | Moon Chamber annually for the southernmost sunset and every 18.61 years to mark the Major Lunar Standstill.
Annually, ten days before and ten days after the Winter Solstice (Dec 11th and Dec 31st with additional imaging on three days before and after those dates), the annual southernmost sunset, offset by the dates above, is imaged on the west side of the image stone. The image is enlarged and brightened by a custom ground glass lens set at the mid-point of the tunnel.
The Alpha Tunnel also serves as a naked eye telescope to view the setting moon. Every 18.61 years (the most recent was 2006) the moon reaches its northernmost and southernmost maximums known as a Major Lunar Standstill. Viewed through the tunnel, the southernmost moonset will form a reverse image on the west side of the image stone. The next Major Lunar Standstill is calculated to be at apogee in 2025.
This image was taken from the Sun | Moon Chamber using the Alpha (East) Tunnel as a naked eye telescope to view the setting moon looking west (towards East Portal). Future construction will provide for light from the east to focus the winter solstice rising sun on the east side of the Sun | Moon Chamber image stone.
The South Space is aligned to the North Star that concentrates the viewer’s attention on the night sky. The central feature is a structure that forms an astronomical instrument similar to the Jai Prakash Yantra in the celestial observatory at Jaipur, India. With this instrument, one can track celestial bodies and events (such as lunar and solar eclipses) as they occur within the timeframe of the 18 year, 11 day Saros Cycle. A single seat provides a view focused on the North Star. The South Space is, in effect, both a space with its own particular characteristics and a calendar for the celestial movements and events that are at the heart of the varied spaces of the Roden Crater project.