When Venus passes directly between earth and the sun, we see the distant planet as a small dot gliding slowly across the face of the sun. Historically, this rare alignment is how we measured the size of our solar system.
When is it?
The next transit of Venus occurs June 5 or 6, 2012, depending on your location. Observers in North America see it the evening of June 5. This will be the last transit of Venus to occur in your lifetime.
Where to Be
Whether and when you can see the 2012 transit of Venus depends on your location. Key highlights include the four "contacts" near the beginning and end of the transit when Venus appears to touch the edge of the sun. Most of North America sees the beginning of the transit in the afternoon and evening (find a clear western horizon!) on June 5, whereas much of Eurasia sees the end of the transit in the morning (find a clear eastern horizon!) on June 6.
I'm Prasanna Deshapriya, currently following my Master degree in Space Applications at USTH in Vietnam. I've graduated from University of Colombo with my Bachelor degree in Physical Science. I'm also an amateur astronomer, gazing at the skies to better discover the universe. Furthermore I voluntarily work as the NPoC of SGAC for Sri Lanka and engage myself in popularization of astronomy & space science during my free time.