Stargazers will have a rare opportunity on Monday to witness Mercury fly directly across the face of the sun, a sight that unfolds once every 10 years or so, as Earth and its smaller neighboring planet come into perfect alignment.<br />The best vantage points to observe the celestial event, known to astronomers as a transit, are eastern North America, South America, Western Europe and Africa, assuming clouds are not obscuring the sun.<br />NASA Television, available on the Internet, will broadcast live video and images from the orbiting Solar Dynamics Observatory and other telescopes.
