We will get to witness something fairly rare, a Venus transit of the sun. It comes around in pairs separated by over a century. It will be visible June 5th in the Western Hemisphere and June 6th in the Eastern Hemisphere. The places of the world that will get to see the entire event include the West Pacific, East Asia, and East Australia. North and Central America will see the start of the transit but the sun will set before we get to see it all. Other parts of the world will just see the ending of the transit.
Venus is often termed “Earth’s twin”. It has similar size, gravity, and bulk composition. However it’s atmosphere is a very dense carbon dioxide and other gaseous layer that traps a lot of heat. It’s extremely hot on the surface, in fact hot enough to melt lead! It is the 3rd brightest object in the Earth’s sky, behind the sun and the moon. There have been 45 space missions targeted as Venus over the years by the U.S. and Russia.
Find out all kinds of cool stuff about Venus, its transit, and much more from the following NASA link. http://www.nasa.gov/topics/solarsystem/features/venus20120531.html