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Graphic by GERRY DESCOTEAUX On the morning of May 15, minutes before the sun rises, Jupiter, Venus, Mars and Mercury each float just above the eastern horizon in a rare planetary conjunction. Inset: One of hundreds of new images from NASA’s Messenger spacecraft mission to Mercury.
Sunday, April 24, 2011

A springtime gathering of alien worlds

Gerry Descoteaux

Meet the road. Take a meeting. Meeting of the minds. Can you sense a theme?

Not to say the Lawnchair is overly excited, but in the early morning skies during the middle of May, there’s an excellent meeting of four of our planetary neighbors.

As a best opportunity target date – a chance to see all four at once – you can witness this unusual conjunction as each of these alien worlds peeks up over the eastern horizon minutes before the sun rises on May 15.

Jupiter, Mars, Venus and Mercury each will hover just above the horizon by about 4:45 a.m.

You’ll need to have a clear view of where the eastern horizon meets the sky. I’d suggest a trip out to the seacoast for your best shot. If you aren’t so lucky, as in my case, look for a flat field facing east, perhaps looking down from a hilltop.

You won’t need a telescope or binoculars to witness this joining of our solar system neighbors. However, it will be a fleeting opportunity, at best. Within 15-20 minutes, as the sun begins its journey up through the horizon, the sky will lighten quickly and the party will be over.

Venus and Jupiter, the two brightest sights in the night sky other than the moon, will be easy to locate. Venus, the slightly brighter of the two because it’s shrouded in thick reflective clouds, isn’t much to look at in a telescope. Jupiter, though, is a wonderful telescopic target with many features to look for.

Jupiter has four large moons, which you can observe in a good pair of binoculars. Interestingly enough, they change positions every night.

Also, of these gathering planets, Jupiter continues racing away from the sun over the course of the upcoming weeks and months, while Mars, Venus and Mercury find their way into the sun’s glow, disappearing for a few months until they emerge, following the sun down to the western horizon during the evening.

Jupiter also serves up other telescopic sights to behold. In a small to medium-size telescope, its massive cloud bands are quite prominent, as is the giant Earth-size storm known as the Great Red Spot. In a good telescope, you should be able to catch this interesting anomaly as it appears every few hours, riding the rapidly rotating Jupiter.

As massive as this gas giant planet is, its rotational speed is absolutely incredible.

Mars, on the other hand, rotates at a rate closer to that of the Earth, and because it’s so close to the horizon in this instance, it won’t be much to look at. Neither will Mercury, but NASA has accomplished another great feat with the Messenger spacecraft mission (see image insert), which has given us never-before-seen views of the planet closest to the sun.

The extraordinary aspect of this conjunction makes it worth getting up a little early to increase the number of trophies filling the Lawnchair Treasure Chest. It’s a rare opportunity to see these neighbors all at once within such a small area of sky.

Considering the rarity of this event, don’t miss the chance to be able to say I was there when.

For June, we’ll take a look at what the summer stargazing season will have to offer. It’s time to get the Lawnchair dusted off, polished and ready for action.

Clear skies!

Gerry Descoteaux, author of “The Lawnchair Astronomer,” is a freelance writer and teacher who has taught astronomy at America Online’s Online Campus for more than 10 years. His course, “Astronomy, An Introduction,” is presented on the Internet. He can be reached at gerry@thelawnchairastronomer.com or www.thelawnchairastronomer.com. His column appears the last Sunday of each month.