Device in NM turns back clock on astronomy
SANTA FE, N.M. — A newly forged steel instrument that can pinpoint the path of stars and planets using the naked eye is a throwback to the years just before the advent of telescopes, returning stargazers in the hills of northern New Mexico to the essentials of astronomy in the past.
Installed at St. John’s College by graduates, the device is a remake of long-lost originals devised by Danish astronomer Tycho Brahe in the late 16th century to chart the location of stars and the orbits of planets.
The so-called armillary sphere consists of four interlocking rings — forged of precision steel and aligned with the north star and equator — combined with a sliding viewfinder moved by hand to measure angles between any celestial object, the horizon and the equator.
Lengthy, painstaking measurements from such an instrument in the late 1500s allowed Johannes Kepler to show that Mars revolved in an elliptical orbit around the sun, disproving the theory of the circular movement of heavenly bodies and setting off a search for new explanations of planetary motion and forces.
“You can often learn things about how science was done in another age by recreating the artifacts and recreating the instruments,” said William Donahue, a retired faculty member and laboratories director at St.
John’s College, whose campus overlooks Santa Fe. “This is a lot of fun because you get to do things that nobody has done for 300 years.”
None of Brahe’s original instruments have survived. Graduates of St. John’s commissioned a functioning replica using Brahe’s original drawings and illustrations. They hired British craftsman David Harber to assemble an instrument from surgical stainless steel. The venture cost upward of $100,000, Donahue said.