The smallest and largest planets dance in the west tonight

If you have good eyes and a flat horizon, then you can spot Jupiter and Mercury this week as they pass each other in the night twilight.

As the planets orbit the Sun, we see their position in the sky change. Right now, Jupiter is (apparently) getting closer to the Sun every day, setting in the west a bit earlier every night. Mercury, on the other hand, is apparently moving away from the Sun, getting higher off the horizon with each passing day. On the evenings of March 14 and 15th the two planets will pass each other, with a closest approach of roughly 2° — about 4 times the width of the full Moon. That’s actually pretty close, and they’ll make a pretty pair in the west just after sunset.

And I do mean just. When the Sun sets, the two planets will be only about 10° off the horizon, where the sky will still be bright from twilight. Even though Jupiter will be shining at a magnitude of -2 (making it the fourth brightest natural object in the sky after the Sun, Moon, and Venus), and Mercury at -1, they might ...

Full story at http://blogs.discovermagazine.com/badastronomy/2011/03/14/the-smallest-and-largest-planets-dance-in-the-west-tonight/