A planetary alignment of Jupiter, Venus and Mercury during the evening of May 24 is an event that will not be seen for another 13 years. All three planets are already coming together, and will continue to inch tighter until the evening of May 24. That evening, the three planets will be seen closer together in the sky than any such alignment occurring for over a decade.

Skywatchers can view this rare planetary trio low in the south-southwest sky early in the evening, just after sunset. On the evening of May 24, the Sun will set a little before 8:15 p.m., just 20 minutes after the Moon begins to rise.

"Here's a beautiful chance to see three planets all together," Alan MacRobert, a senior editor at Sky & Telescope magazine, said. "Add the Earth under your feet, and you're seeing half of the solar system's planets at once. They'll be a lovely part of the spring twilight."

The three planets will all be within 2 1/2 degrees of one another on the evening of May 26. This will allow amateur astronomers the rare chance to glimpse three planets at once using a pair of binoculars. Jupiter will be snuggled right up next to Venus the following evening. On May 28, Venus will be as close to Jupiter as it will get during this alignment. As it appears to move away from Jupiter, Venus will shine six times brighter than the giant world.

"The view should be best about 30 to 45 minutes after sunset," MacRobert added. "And think photo opportunity. Set up a camera on a tripod, zoom to the max, and try different time exposures."

The three planets will remain close to one another for a month or so, with the alignment falling apart after May 24. Jupiter will be the first of the trio to disappear under the horizon, at the beginning of June. Mercury will be visible just above Venus, until June 7. The smallest, quickest planet is also usually the toughest to find in the night sky, but Mercury will be bright enough during the alignment to be seen under all but the most light-polluted skies.