The Sommers-Bausch Observatory at the University of Colorado at Boulder is hosting an open house 聴 weather permitting 聴 to view a very rare planetary phenomenon on Monday, Nov. 15, from 1:30 p.m. to 3:30 p.m.
Using a heliostat 聴 a specialized solar telescope that transfers the sun聮s light via a series of mirrors and lenses and projects it on a flat surface for safe viewing 聴 people will see Mercury聮s silhouette gliding along the upper edge of the sun as it passes between Earth and the sun.
Such a "transit" by Mercury happens only when the innermost planet passes directly between the Earth and sun, an event that occurs only 13 times a century and hasn聮t been visible here for 26 years, according to Keith Gleason, manager and laboratory coordinator at the Boulder observatory.
"The last two times the phenomenon occurred, the sun had already set, making it impossible to view here in North America," Gleason said.
Mercury will appear as a miniature black dot, about one-one hundred eightieth the diameter of the sun, skimming along the edge of the sun.
"This particular transit is a "grazing" one, with Mercury聮s disk just barely crossing the edge of the sun. No one has ever seen a similar event before, since the last time a grazing transit of Mercury occurred was before the invention of the telescope," Gleason said.
Sommers-Bausch Observatory is located just east of Fiske Planetarium on Regent Drive on the CU-Boulder campus. For more information call (303) 492-6732, or visit the homepage at .