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miércoles, 11 de mayo de 2011

Night Sky News: See the Tightest Planet Gathering Yet This Century

Image courtesy StarDate Magazine

Talk about an early morning eye-opener! Every day this month, about 20 to 45 minutes before sunrise, sky-watchers will get a rare opportunity to watch four worlds—Mercury, Venus, Mars, and Jupiter—in the closest planetary grouping yet seen this century.

This, planetary conjunction—astro-lingo for when planets cluster together in the heavens—has provided some impressive sights already. But the early-bird sky show is really culminating this week as they form their tightest grouping yet!

Jupiter, the gas giant and second brightest of the bunch, will glide past Venus on May 10 and 11, making the larger world easy to spot despite it being less than a quarter as bright as the goddess of love. Most impressive is that the two planets will be separated by only 0.5 degrees, which means you could easily cover the starlike pair with just your thumb on an outstretched arm.

Then, on May 12 all four worlds will be clustered within 6 degrees of each other in the dawn sky. That’s equal to the width of 12 full moon disks side by side—quite a pretty sight.

Faint little Mercury is the third brightest planet in the parade, just to the lower right of the Venus-Jupiter pair. But what makes it a challenging target is that Mercury is five to ten times fainter than Jupiter and much closer to the horizon. The innermost planet will remain a few degrees to the lower right of the brighter Venus throughout this period.

However, ruddy colored Mars is the trickiest to spot because it’s just one-hundredth as bright as Venus. The red planet starts very low in the sky, but eventually catches up with the Venus-Mercury pairing this week.

Your best bet to pick out Mercury and Mars through the bright twilight is by using binoculars when you scan just below Venus.

While this planetary alignment can be glimpsed from around the world, best views will be centered around the tropics, where the planets will shine brighter and higher in the predawn sky.

For observers in mid-latitude regions such as southern Canada, most of the continental U.S., and Europe, the planets will hug the eastern horizon very closely, making it more of a challenge to see the entire set.

No matter where you are, the most important advice is to get a clear, unobstructed view of the low eastern horizon 30 to 45 minutes before your local sunrise.

This dazzling planetary meeting will begin to slowly disband in the second half of May, but as a grand finale to the sky show, our own crescent moon will add to the mood from May 29 to 31, making for a picturesque pose with Jupiter and then Venus.

Sky-watchers haven’t seen a cosmic morning lineup like this since 1996! And if you miss this one, you will have a long wait, because the next big planetary conjunction—which will involve all five of the naked-eye planets, plus the moon—won’t occur until September 8, 2040.While all the hoopla surrounds the four bright planets, there are two other members of the club getting in on the action.

Both Uranus and Neptune sit to the far upper right of the quadruple pack of planets in the southeastern sky. They are both significantly fainter, and so you will need binoculars to glimpse them.

Neither will look all that impressive, appearing as greenish-blue tinted, fuzzy stars. A small telescope, however, will begin to reveal their tiny disks.

Out of the eight official planetary members of our solar system, we are lucky enough to see six huddled together in one small section of the sky.

We live on one of the remaining member worlds, so that leaves one missing: Where is Saturn? The ringed gas giant sits by its lonesome in the evening sky, shining brightly high above the southern horizon.

Andrew Fazekas, aka The Night Sky Guy, is a science writer, broadcaster, and lecturer who loves to share his passion for the wonders of the universe through all media. He is a regular contributor to National Geographic News and is the national cosmic correspondent for Canada’s Weather Network TV channel, space columnist for CBC Radio network, and a consultant for the Canadian Space Agency. As a member of the Royal Astronomical Society of Canada, Andrew has been observing the heavens from Montreal for over a quarter century and has never met a clear night sky he didn’t like.

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