The Sommers-Bausch Observatory at the University of Colorado at Boulder is hosting an open house, weather permitting, to view a rare "Mercury transit" of the sun on Wednesday, Nov. 8, from 11:30 a.m. to 4:30 p.m.
Using the observatory's heliostat -- a specialized solar telescope that transfers the sun's light via a series of mirrors and lenses and projects it on a flat surface for safe viewing -- people will see Mercury's silhouette on the sun's surface 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. The last Mercury transit visible in Colorado occurred on Nov. 15, 1999, and the next one won't happen until May 9, 2016.
"The most interesting part to me will be when the shadow of Mercury first appears on the sun, which will happen shortly after noon," Gleason said. "The sun setting also will be something to see" because the transit will still be occurring. The sunset will occur in Boulder at approximately 4:30 p.m.
Visitors who want to watch Mercury's first contact with the sun should arrive at the observatory well before noon, Gleason said.
People also can watch the Mercury transit at Fiske Planetarium, where live video from the observatory will be displayed throughout the afternoon. Suzanne Traub-Metlay, education programs manager of the planetarium, will give presentations from 1 p.m. to 2 p.m. and 3 p.m. to 4 p.m. in the planetarium theater about the Mercury transit and NASA's MESSENGER spacecraft mission to Mercury.
If Nov. 8 is a cloudy day, the planetarium will show a live feed of the transit from NASA TV.
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 Web site at lyra.colorado.edu/sbo/public/special.html.