Only eyes are necessary to tune in celestial parade Six planets visible on southwest horizon

December 03, 1997|By Frank D. Roylance | Frank D. Roylance,SUN STAFF

Your assignment tonight -- or any clear night this week -- is to go outside after dark, look up and treat yourself to a beautiful view of six planets visible to the naked eye, including the one you're standing on.

The celestial parade actually features eight planets, but a glimpse of Neptune and Uranus requires telescopes. Only Pluto is missing.

"It's lovely," said Lucy Albert of the Harford County Astronomical Society. "It's neat to be able to see eight planets all in one evening."

This week, a waxing crescent moon will join the evening spectacular as a sort of pointer, guiding observers through the lineup.

Jim O'Leary, director of the Maryland Science Center's Davis Planetarium, said Venus has been so bright in recent weeks that people have been calling to ask what it is. "Sometimes people just seeing it for the first time think it's a very bright plane in the sky, or something artificial," O'Leary said. Venus will be at its brightest on the 11th.

Herman Heyn, Baltimore's "Street Corner Astronomer," has been lugging his telescope each night to the Rotunda shopping center on 40th Street. Each night he's given scores of shoppers and moviegoers a telescopic view of Saturn.

The ringed planet is also visible to the naked eye. But through his telescope, Heyn said, it has been so sharp, some people accuse him of using a photographic slide.

"Some people just won't believe it's real," he said.

But it is. "If it were a slide," he said, "it wouldn't look so good."

Geoff Chester, a spokesman for the U.S. Naval Observatory in Washington, said it's a common misconception that the planets are now lined up "like pearls on a string on the same side of the sun." They're not. Earth, Venus and Mercury are circling on one side of the solar system. The rest are orbiting on the other side.

They're actually scattered around 130 degrees of the solar system, something that happens quite often, according to the Hayden Planetarium in New York.

But "set against the backdrop of space," Chester said, "we're able to see them at the same time." And, at a convenient nighttime hour. That's what's rare.

Counting leftward from the southwest horizon, beginning just after sunset, the planets include:

Mercury, barely visible on the horizon immediately after sunset about 4: 50 p.m.

Mars, reddish and dim, just to the right and below brilliant Venus.

Venus, the brightest object in the night sky except for the moon.

Jupiter, nearly as bright as Venus, but higher and farther east.

Saturn, dimmer and a yellowish white, high above the southern horizon.

Too distant to be seen without a telescope are Neptune -- somewhere above and to the right of Venus -- and Uranus, now to the left of Venus, part way to Jupiter.

The five naked-eye planets will be visible together again late next summer, in the pre-dawn sky.

"What's great about this planetary lineup is that the moon will be passing by every one of these planets," O'Leary said. "It helps you identify them."

On its eastward orbit around Earth, the moon stood to the right of Mars last night. By tonight it will have moved to a spot directly above Venus -- a striking sight.

Tomorrow night the moon will be to the right of Jupiter. By Monday and Tuesday evenings, it will appear to be passing Saturn.

Venus, Jupiter and Saturn are easily spotted, even from downtown Baltimore. "They just look like brilliant stars, except they're not twinkling," O'Leary said.

Stars are huge and burn with nuclear fires like our sun. But they are so far away, Earth's turbulent atmosphere distorts their slender beams, making them appear to twinkle.

The planets are far smaller than stars. But they are much closer to Earth and present a larger face to observers. Their disks reflect so much of the sun's light toward Earth, they shine with a steady light.

This month's planetary lineup will shift slightly each night as the planets -- Earth included -- move about their orbits. Mercury, then Venus, will drop into the sunset as they orbit in front of the sun en route to becoming morning "stars" in February.

"It's what the ancients saw, and they would try to figure out what was going on," Chester said. Today, "When you see these little dots in the sky, remember that's a place, and with the exception of Mercury, we have explored all of them quite thoroughly."

The Galileo spacecraft is circling Jupiter. Cassini is en route to Saturn. Last summer, Pathfinder sent back pictures from Mars.

While it lasts, the alignment presents amateur astronomers with a happy problem -- too much to see. "There'd be a lot of swinging [the telescope] around," Heyn said. "I have to perform triage.

"I love to show people Jupiter's moons," he said. With a good pair of binoculars and a steady hand, four of those tiny moons can often be seen as white dots at Jupiter's side.

Heyn's favorite in these rich December skies is Saturn and its rings. "Most people don't realize they can see it anywhere aside from a book. They're usually quite thrilled," he said.

When skies are clear, Heyn sets up in the Rotunda's rear parking lot about 5 p.m. and stays until 8 p.m. On clear weekends, he often can be found at Harborplace or in Fells Point.

Pub Date: 12/03/97

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