Md. may see total lunar eclipse tomorrow

Clear skies are forecast

show would be first since 2000 to be visible here

November 07, 2003|By Frank D. Roylance | Frank D. Roylance,SUN STAFF

Cheated by geography and bad weather, Marylanders have missed out on every lunar eclipse since January 2000.

But if the forecast for clear skies holds tomorrow, Marylanders will get another chance to watch a total lunar eclipse as the moon plunges through Earth's shadow. This time, the northeastern United States will have a ringside seat.

"It's one of those experiences we share with the many people who have lived over the centuries, and the millennia," said Jim O'Leary, director of the Maryland Science Center's Davis Planetarium.

"It sort of turns your attention to things beyond the daily routine and gets you thinking about things cosmic for a short period of time."

The celestial show will begin at dinnertime tomorrow, making it convenient to watch. But skywatchers will have to be punctual -- this eclipse is shorter than most, with 24 minutes and 32 seconds of totality.

At 6:32 p.m. EST -- about 90 minutes after the full "frost moon" rises in the East -- it will begin to cross into the Earth's umbra, the dark core of the circular shadow the planet casts almost a million miles into space. The moon will dim gradually from the left as it moves from direct sunlight into shade.

The eclipse will become total at 8:06 p.m., when the moon is fully engulfed in shadow. Look for a much-subdued, amber disk glowing above the southeastern horizon.

Then, at 8:30 p.m., the lower edge of the moon will begin moving back into direct sunlight. The whole face of the moon will be fully illuminated again by 10:04 p.m.

Tomorrow's event will be visible in its entirety from Europe and West Africa to Brazil, eastern Canada and the northeastern United States.

It's the second lunar eclipse of the year, but clouds in Maryland obscured the first one May 15.

If you miss this one, the next total eclipse of the moon visible here will be Oct. 27, when totality will last for one hour and 21 minutes.

"People are just fascinated by these because of the accuracy with which they can be calculated," O'Leary said.

Babylonian observers discovered 2,500 years ago that eclipses with similar geometries could be organized into predictable cycles, called saros (repetition) cycles.

Each cycle produces one lunar eclipse every 223 full moons (generally every 18 years, 11 days and eight hours) with a total of perhaps 70 eclipses over 1,200 years.

But 42 different saros cycles are running at any given time, producing a lunar eclipse somewhere every six months.

Astronomers say tomorrow's eclipse is the last and shortest total lunar eclipse in Saros 126, which began with a partial eclipse July 8, 1210.

The first of 14 total eclipses in that cycle occurred June 19, 1769. After tomorrow's, they're all partial through the end of the Saros 126 cycle in 2490.

The total eclipse predicted here next fall is part of a different cycle, Saros 136.

Though the moon will be fully in shadow during totality, it will not disappear entirely.

That's because some of the sunlight shining on the daytime side of Earth is scattered into space as it filters through the atmosphere at the rim of the planet's disk.

Some of that light is deflected toward the moon. It bounces off the lunar surface and back to Earth, allowing us to see it. But it's a dimmer, ruddier moon we see.

"Eclipses tend to get dark or light depending on volcanic activity," O'Leary said.

Eruptions put more volcanic ash into the upper atmosphere, producing darker, redder eclipses. It's the same filtering phenomenon that colors our sunrises and sunsets.

With few big eruptions recently, "we wouldn't expect it to get very dark," he said.

Because the moon will be passing near the lower edge of Earth's shadow, however, its lower rim will appear brighter than other portions that are deeper in shadow, giving it an eerie, bottom-lit appearance.

Lunar eclipses are safe to observe with the naked eye and easy to see anywhere skies are clear, even in urban locations. Binoculars and small telescopes can enhance the view.

The Maryland Science Center will open its Crosby Ramsey Memorial Observatory at 5:30 p.m., weather permitting. It is free. Call 410-545-2999 after 5 p.m. tomorrow for information.

Baltimore's "street corner astronomers" also plan to be on duty.

Herman Heyn will offer views of the eclipse from the 3100 block of St. Paul St. in Charles Village. Darryl Mason will be in Fells Point.

For more information on the Web, visit http://science.nasa. gov.

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