A partial lunar eclipse tonight will most likely be obscured by cloudy skies, but astronomers promise a more impressive total eclipse in December.
But if there is a break in the clouds, backyard astronomers and insomniacs across Maryland will be able to watch more than two-thirds of the full moon vanish.
The moon's bright disk will enter the darkest part of the Earth's shadow beginning at 11:27 p.m. EDT. A maximum of 69 percent of the moon will be in darkness at the midpoint in the eclipse, just before 1 a.m. By 2:27 a.m., the moon will have returned to its full brightness.
It's safe to watch a lunar eclipse with the naked eye, but binoculars or a small telescope can make the experience more interesting.
Simply find a comfortable spot with a clear view of the full moon, about halfway up in the southern sky.
The first part of the moon to pass into the Earth's shadow, at 11:27 p.m., will be in the upper left quadrant.
The shadow will then appear to spread slowly across the upper two-thirds of the moon's disk, before retreating off to the upper right.
The whole show will last about three hours. If skies are not cloudy, everyone in most of the eastern half of North America, and all of South America, will get a chance to watch the eclipse from start to finish.
Bob Melrose, a National Weather Service meteorologist at Baltimore-Washington International Airport, said yesterday there would be mostly cloudy skies with a 40 percent chance of showers tonight.
The culprit is a storm front that was expected to move into Baltimore from the south earlier in the weekend, but will not arrive until this afternoon, he said.
Jim O'Leary, director of the Davis Planetarium at the Maryland Science Center, said tonight's eclipse -- if clouds don't interfere -- may be especially dark because of dust and gases pumped into the Earth's upper atmosphere by the June 1991 eruption of Mount Pinatubo in the Philippines.
Eclipses since the eruption have been unusually dark because more of the light passing through the Earth's upper atmosphere is being absorbed by the volcano's debris, Mr. O'Leary said.
Tonight's eclipse is only "the appetizer" for an even more impressive total lunar eclipse around dinnertime Dec. 9.
On that night, the full moon will move into the Earth's shadow beginning shortly after sunset and will remain in full shadow from p.m. until 7:21 p.m.