Unless you plan to live to December 2117, Tuesday, June 5, 2012, will be your once in a life time opportunity to view the Transit of Venus across the Sun.
In the United States, the transit begins at approximately 6:04 p.m. EDT, 5:04 CDT, 4:05 MDT, and 3:06 PDT. The entire event will last about 6 hours and 40 minutes.
The transit of Venus means that the planet Venus will cross across the visible surface of the Sun. The first 18 minutes of the event when Venus first begins to appear on the outer edge of the Sun are considered the most spectacular viewing.
The Transit of Venus occurs when the Sun, Venus, and Earth are lined up together. The difference in the periods of the orbits of Earth and Venus about the Sun makes the event so rare.
Caution must be used when viewing this event. Do not look directly at the Sun. Looking at the sun with no protection for your eyes can cause severe permanent eye damage including blindness.
Safe viewing can be achieved using a telescope binoculars or glasses with filters specifically manufactured for solar observing. Alternately you can use the pinhole in a box method to project the image on to a white sheet of paper. Safe viewing instructions should be read here before you look at the event.
Use NASA’s map here to get an idea of where to look and the timing of the event’s progression. NASA’s web cast of the Transit of Venus can be viewed at this web site.