Planets fill skies with rare views

Solar system aligns for generational treat

May 06, 2002|By Frank D. Roylance | Frank D. Roylance,SUN STAFF

In a kind of celestial traffic jam, all five planets visible to the naked eye are converging in the western sky each evening this month, creating a majestic spectacle that won't be seen again this easily for decades.

With no more than a clear night, normal vision and a wide-open view of the western sky, anyone should be able to step out under the stars and spot all five -- Jupiter, Saturn, Mars, Venus and Mercury -- maneuvering in the same heavenly intersection.

"It's part of a family portrait," said Jim O'Leary, director of the Maryland Science Center's Davis Planetarium.

If you include the Earth in the view, he said, "you can actually say there are six planets you are looking at. So you are looking at two-thirds of the solar system's planets." (Uranus, Neptune and Pluto can't be seen with the naked eye.)

On Tuesday, May 14, a seventh "world" -- the Earth's crescent moon -- will move in to join the party.

Astronomers say this year's event is the tightest and most easily seen grouping of these five planets since 1940. And it will be 2040 before anything like it happens again. "So this is almost a once in a generation kind of event," O'Leary said.

The five planets aren't really close together, of course. Tiny Mercury is 84 million miles away. Brilliant Venus is now 137 million miles away, and Mars shines faintly at a distance of 218 million miles. Giant Jupiter is 525 million miles away, and the ringed planet Saturn is 920 million miles out.

But from Earth's perspective, they are all out there in the same general direction, like the headlights of approaching traffic. So they appear to be bunching in one corner of the sky.

The grouping has absolutely no scientific importance. And the combined pull of gravity from all those planets is so diminished by the vast distances from Earth that it can have no discernible effect on us -- no earthquakes or other calamities. It's just a rare and beautiful sight to see.

"It's been getting a lot of publicity already," O'Leary said. "We've been getting a number of phone calls and e-mails. People want to know where to look."

The five planets have been gathering in the western sky for months. But some of the best views from Earth are coming up in the next two weeks.

Each night, all the planets except Jupiter will appear to shift their relative positions. Saturn and Mercury are inching closer to the sunset each night, and Venus is rising toward a spectacular rendezvous with Jupiter on June 3.

The most important things stargazers will need are clear skies and a good sky map to help them identify and follow the planets. In addition to the two maps with this article, others are available on the Internet or in amateur astronomy magazines available at newsstands.

Here's the basic drill:

Start looking at about 8:30 p.m. The sun will have set and the sky will be darkening.

That brilliant "star" just above the western horizon is Venus, the second planet from the sun. The second-brightest object in the sky is Jupiter. It is easily spotted well above Venus and to the left.

This past weekend, as the darkness deepened, another somewhat dimmer "star" gradually became visible immediately to the left of Venus -- separated by the width of two or three fingers held at arm's length. That is Saturn, the giant ringed planet. (NASA's Cassini spacecraft, launched in 1997, is due to arrive there in July 2004.)

As the sky gets darker still this week, another, much fainter dot of light will appear just above Venus and Saturn, forming the apex of an equilateral triangle. That is Mars. (NASA's Mars Odyssey and Global Surveyor spacecraft are orbiting there, beaming back pictures and scientific data.)

The most difficult planet to find may be Mercury, the planet nearest to the sun. Look for a tiny dot of white light emerging from the dusk just below Venus and to the right -- at arm's length, perhaps a fist's width away. (Binoculars might help pick it up earlier.)

During the coming week, Mercury will gradually vanish into the sunset. Mars and Saturn, too, will appear to move closer each night to the horizon.

On May 14, a slender crescent moon will be visible right beside Venus, in a dramatic pairing that is sure to draw attention. Also, Venus will climb in the sky each night this month, moving toward its striking close encounter with Jupiter on June 3.

On that evening, the two brilliant planets will appear less than two finger-widths apart, with Venus on top. In reality, Jupiter is almost five times farther away than Venus -- some 50 light-minutes away.

For sky maps and more, go to http://skyandtelescope.com and click on "A Rare Dance of the Planets."

Seeing stars

The Maryland Science Center's Crosby Ramsey Observatory, at the Inner Harbor, will be open from 5:30 p.m. until 10 p.m., Monday through Thursday, for the next two weeks, weather permitting, to offer visitors a free look at the sun and planets. Call 410-545-2999.

The Maryland Space Grant Observatory at Johns Hopkins University's Bloomberg Physics Building is open each Friday at dusk, weather permitting. Call 410-516-6525.

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