'Planet Collectors,' This Is Your Week

Keep an eye to the sky this week for a chance to see a planetary hangout. Five planets—Mercury, Jupiter, Venus, Uranus, and Mars—will line up near the moon, per the AP. More details:

• Where and when can you see them? The best day to catch the whole group is Tuesday. You'll want to look to the western horizon right after sunset, says NASA astronomer Bill Cooke. The planets will stretch from the horizon line to around halfway up the night sky. But don't be late: Mercury and Jupiter will quickly dip below the horizon around half an hour after sunset. The five-planet spread can be seen from anywhere on Earth, as long as you have clear skies and a view of the west. "That's the beauty of these planetary alignments. It doesn't take much," Cooke says.

• Binoculars necessary? Maybe. Jupiter, Venus, and Mars will all be pretty easy to see since they shine brightly, Cooke says. Venus will be one of the brightest things in the sky, and Mars will be hanging out near the moon with a reddish glow. Mercury and Uranus could be trickier to spot, since they'll be dimmer. You'll probably need to grab a pair of binoculars. If you're a "planet collector," it’s a rare chance to spot Uranus, which usually isn't visible, Cooke says. Look out for its green glow just above Venus.
• Does this happen often? Different numbers and groups of planets line up in the sky from time to time. There was a five-planet lineup last summer, and there's another one in June, with a slightly different makeup. This kind of alignment happens when the planets' orbits line them up on one side of the sun from Earth's perspective, Cooke says.

(More planets stories.)