The planet Venus will begin its pass between the Earth and Sun on the Tuesday, June 5th at about 3:09 pm PDT, 4:09 pm MDT, 5:09 CDT, 6:09 pm EDT, or 22:09 UT. If you miss this one you'll have to wait quite a while. The next Venus transit will occur on Dec. 10, 2117 at 23:58 UT
Be sure to get "The Planetary Transit Special Award (Venus Transit)" from the Astronomical League and NASA! See http://astroleague.org/PlanetaryTransit_Venus2012
There will be a live webcast of the Venus transit from the summit of Mauna Kea courtesy the W.M. Keck Observatory.