By Megan Garber for The Atlantic, From Mashable

It’s prom season — for the planets.

Every couple of years, give or take, planets get together in the night sky in such a way that they seem to be aligned with each other. They seem to be, really — from Earth’s perspective — shyly approaching each other, asking each other to dance. This planetary mixing-and-mingling is scientifically known as “planetary conjunction” … but it’s colloquially known, probably because of the corsages and the limos and the awkward dancing, the “Dance of the Planets.”

We’re about to have an especially rare and wonderful version of that dance. The night skies this week, provided they’re clear, will reveal, yep, a triple conjunction — a planetary crossover featuring the three brightest planets as seen from Earth: Mercury, Venus and Jupiter. Between May 24 and May 29, the celestial trio will fit within a circle whose diameter is less than 5 degrees wide on the sky’s dome. They’ll dance around each other (as, ostensibly, “Feel This Moment” plays in the background).

Here’s more on the planets’ big night out:

The planets will be at their closest, with Jupiter and Venus just 1 degree apart, on 28 and 29 May. All three planets will form a straight line on 31 May as they gradually move apart from each other.

For U.S. observers, the best time to look is also toward the western sky at twilight, with the three planets appearing close to the horizon. From 23 May, the three planets will be close enough together to be viewed through a pair of binoculars, forming a triangle on 24 May before drawing close and orbiting apart.

So, everyone, take your awkward photos of the planets’ prom night now. This week’s dance will be, Earth Sky notes, “the closest grouping of three planets until January 2021.”

For more on this story go to:

http://mashable.com/2013/05/23/dance-of-the-planets/?utm_medium=feed&utm_source=feedburner&utm_campaign=Feed%3A+Mashable+%28Mashable%29

Related story:

Closest grouping of three planets until the year 202

By Bruce McClure From EarthSky

After sunset on Sunday, May 26, or Monday, May 27 – depending on where you live worldwide – will showcase the closest grouping of three planets until January 2021. Be sure to view the planets Mercury, Venus and Jupiter over the west-northwest horizon (in the same direction as sunset) some 45 to 75 minutes after sundown.

Don’t wait until nightfall, though, because this grouping of planets follows the sun beneath the horizon around one and one-quarter hours after sunset. If you have binoculars, you can start your search 30 minutes (or less) after the sun dips beneath the horizon. All three planets should easily fit within the same binocular field of view.

Setting times for the sun and planets in your sky

Continue to watch the planetary drama for another week or so, and you’ll soon find out why the Greek word planet means wanderer. Mercury and Venus are climbing upward, away from the setting sun, whereas the king planet Jupiter is sinking into sun’s glare. Jupiter, as a matter of fact, is bound to disappear from the evening sky in early June.

Mercury, on the other hand, will reach its greatest eastern elongation – greatest angular distance – from the setting sun on June 12, 2013. Venus will be in hot pursuit of Mercury all the while, so use Venus – the sky’s brightest planet – as your guide to Mercury from now until the June solstice.

But for the next few days, watch the extra-close planetary threesome – Mercury, Venus and Jupiter – to pop out over the west-northwest horizon as dusk ebbs into darkness.

For more on this story go to:

http://earthsky.org/tonight/closest-grouping-of-three-planets-until-the-year-2021