After a late snack of turkey leftovers Sunday night -- and if the weather cooperates -- Marylanders should be able to step outdoors and watch the last total lunar eclipse to be seen here until 1996.
Curiously, the eclipse falls on the same dates as a partial lunar eclipse that occurred on Nov. 28-29, 1621, the year of the first "Thanksgiving" in Plymouth, Mass.
That one was a partial eclipse, "with somewhat less than a quarter of the moon being covered," said Dr. Leroy E. Doggett, chief of the nautical almanac at the U.S. Naval Observatory in Washington.
Sunday's eclipse will be total.
Visible anywhere in North America where the skies are clear, it begins at 11:40 p.m. EST on Sunday. Totality will last from 1:02 a.m. until 1:50 a.m. Monday. The moon will leave the Earth's "umbra," or shadow, at 3:12 a.m.
The weather forecast is not promising, however, calling for cloudy skies and rain Sunday, and, on Monday, continued clouds with cold breezes and a chance of rain or snow, said Ken Shaver, a forecaster for the National Weather Service at Baltimore-Washington International Airport.
A lunar eclipse occurs when the full moon, on its monthly orbit around Earth, passes through the shadow cast by Earth.
"If you can imagine the umbra as a circle-shaped shadow in space, the moon will be passing through the lower part of the circle," said Jim O'Leary of the Davis Planetarium in Baltimore.
"That's not the darkest part of the shadow, so the moon might remain visible during the eclipse and might have more of the color -- orange, reds or coppers -- seen during some lunar eclipses."
The last several lunar eclipses have been unusually dark, leaving the moon's disk almost invisible during totality. Astronomers blamed the volcanic haze pumped into the atmosphere by the 1991 eruption of the Pinatubo volcano in the Philippines. The haze absorbed and blocked much of the sunlight that would otherwise have been scattered by the atmosphere at the Earth's horizons, bathing the moon in a faint reddish glow as it passed through totality.
David H. Levy, a comet-hunter and astronomy writer at the University of Arizona, said much of the volcanic haze has now cleared, but not all of it. A bit more light may seep through during this eclipse.
"It's really hard to predict these things," he said. "My guess is it would probably be an average eclipse, maybe a little bit darker than average . . . but not as dark as the last several."
Mr. Levy predicts the moon in totality will be "easy enough to see, probably a ruddy, reddish color. But nature is a funny creature and could make us all wrong."
In 1621, the Pilgrims may not have seen the moon darken. There is "absolutely no mention" of the eclipse in any of the settlers' writings, said Carolyn Travers, research director at Plimoth Plantation in Massachusetts. "It could have been cloudy."
Under the Julian calendar used at that time, the eclipse would have been recorded on Nov. 18 and 19. That would have placed it several weeks after the three-day harvest celebration -- attended by 52 pilgrims and 90 Indians -- that later came to be called the "first Thanksgiving."
That event took place after the fall harvest, between Sept. 24 and Nov. 9, 1621, on the Julian calendar, said Ms. Travers.
There are no dangers associated with viewing a lunar eclipse directly. Unlike the direct sunlight seen during an eclipse of the sun, the moon's reflected light is harmless.
No telescopes or binoculars are needed.
"If people can see the moon from their backyard, they can easily see the eclipse," Mr. O'Leary said.
But the view can be enhanced by a telescope. The Maryland Science Center staff plans to have telescopes and explanations available at the Inner Harbor from 11:30 p.m. until at least 1:30 a.m.
"We welcome people to come down and take a look," he said.
This will be the first total lunar eclipse visible in eastern North America since Dec. 9, 1992, and the last one until April 3, 1996.
The next one visible throughout North America will be Sept. 27, 1996.