The moon will be ducking into the shadows tomorrow night for its second total eclipse this year, and the last one visible in Maryland before 2000.
At 9: 12 p.m., the full moon will begin drifting into the conical shadow cast into space by Earth. By 10: 19 p.m., it will be in full shade, where it will remain for more than an hour.
Lunar eclipses are safe to view with the naked eye, and a pair of binoculars or a small telescope will enhance the experience.
Weather permitting, the Maryland Science Center and members of the Baltimore Astronomical Society will sponsor a public eclipse-viewing in front of the science center at Baltimore's Inner Harbor, beginning at 9 p.m.
The Harford County Astronomical Society plans an open house at the Harford Community College observatory, also starting at 9 p.m. And Baltimore's "Street Corner Astronomer," Herman Heyn, will make his telescope available to the curious at Fells Point.
In College Park, the University of Maryland will make telescopes and astronomers available in front of Memorial Chapel, in the south campus area.
If the lunar eclipse April 4 is any guide, the face of the moon in full eclipse will blush a coppery color. The color is produced when sunlight filters through the atmosphere around Earth's rim. The light takes on the red-orange glow of sunset and sunrise, which we see reflected dimly from the moon's surface.
Astronomers have long used the color of the moon during a total eclipse as a rough measure of the amount of dust in Earth's upper atmosphere. After the eruption of Mount Pinatubo in 1991, for example, volcanic dust levels rose. The dust absorbed more of the sunlight at Earth's rim, and lunar eclipses for the next two years appeared dark, so that the eclipsed moon was nearly invisible.
Since then the dust has settled. By the April 4 eclipse, more light was getting through, and the eclipsed moon had brightened to a coppery orange.
The complete celestial event will be visible throughout the eastern half of North America, all of Central and South America, ++ much of Western Europe and West Africa, at least where skies are clear.
The show will end when the moon finally leaves the darkest portion of Earth's shadow at 12: 36 a.m. Friday.
April's eclipse came with the added attraction of a bright comet -- Hyakutake -- hanging in the northwestern sky. This time, Saturn will provide the side show.
The yellowish, ringed planet will be at opposition (when Earth lies directly between the sun and the planet) and its brightest in years. It should be visible just below and to the right of the dusky moon.
Sky & Telescope magazine reports that this will be the first time a totally eclipsed moon and Saturn have appeared in close company over North America since Sept. 13, 1848. It won't happen again until 2008, when the bright star Spica will make it a trio.
North American observers who miss this week's event because of clouds will get another chance when the moon is eclipsed March 23. It will be a partial eclipse, but the moon will be 98 percent obscured by Earth's shadow -- not a bad consolation prize.
The next total lunar eclipse visible in the eastern United States will occur in January 2000.
For those hoping to capture the eclipse on film, "Street Corner Astronomer" and astro-photographer Herman Heyn offers this advice:
To minimize vibration, use a tripod and a cable shutter release, available at camera stores for around $10. No flash is needed.
A telephoto lens is best. With a 200 mm lens, the moon will appear the size of a pinhead on your picture. But even with a standard 50 mm lens, the moon and Saturn will make a pretty picture. Include a tree or house for added interest.
Use ISO 200 speed film. Color slide film will avoid the uncertainties of commercial photo printing.
While the moon is fully or mostly lighted, set the camera for 1/400th second and "bracket" shots at f16, f11 and f8. When the moon is partly illuminated, try 1/125th second at f11, f8 and f5.6. During totality, set the lens to f4, and try exposures from 1 to 5 seconds.
Pub Date: 9/25/96