Over the last couple weeks, you may have heard about a rare astronomical event taking place in the evening sky. And it's not too late to get in on the observing.

For a couple more days, the planets Mercury, Venus, Mars and Saturn will cluster in the western sky just after sunset, all within a circle about the width of your first held at arm's length. Jupiter will shine brightly above them. This five-planet show is visible with the naked eye for about an hour, though you'll need a clear view of the western horizon and binoculars will help to see faint Mercury, which will be just below the much brighter Venus. This planetary gathering won't be easily visible again from Earth for 58 years.

Two of the planets will nearly align this Friday. As night falls, Venus and reddish Mars will appear just one-third of a degree apart - that's about half the width of your pinky finger held at arms length. It'll be a rare chance to peer through a telescope and see two planets at once.