This weekend Mercury, Venus and Saturn are going to crowd together in a patch of sky no bigger than your thumb. Astronomers call it a “conjunction” and it’s going to be spectacular.

The show begins on Saturday evening, June 25th. Step outside and look west toward the glow of the setting sun. Venus appears first, a bright point of light not far above the horizon. As the sky darkens, Saturn and Mercury pop into view. The three planets form a eye-catching triangle about 1.5° long, easily hidden by your thumb.

http://science.nasa.gov/headlines/y2005/22jun_spectacular.htm?list179029

Interesting info about Saturn on this page as well.