Lunar eclipses, often overlooked in favor of the more spectacular solar eclipses, deserve more respect than they get. Unlike the rare total solar type of eclipse, which is visible only along a narrow track sweeping across Earth's surface, lunar eclipses can be observed from anywhere on Earth's night-time hemisphere -- weather permitting. Every year or two on average, we in San Diego have a chance to observe one. The next opportunity comes on Wednesday evening, October 27, when the full moon drifts into the darkest heart of Earth's circular shadow. The upcoming eclipse favors observers in North America, South America, Europe, and Africa. Only in the Americas, however, can it be seen during the evening hours.
For San Diegans, the circumstances for viewing this eclipse are as good as they get. Clear skies, free of annoying coastal overcast, are common if not absolutely dependable on October evenings, and the night air is not yet too chilly. You can't beat the timing: On the West Coast, the eclipse begins near sundown and ends before typical bedtime. The following "itinerary" reveals what you can expect to see next Wednesday evening.
* 6:14 p.m. The sun has just set, and the oddly shadowed moon, nearly full but with a small, curved "bite" taken out of it, materializes near the eastern horizon. During the next 69 minutes, the moon continues to slide into Earth's umbra, or dark shadow cone. As it does so, the remaining sunlit moon appears as an increasingly thinner crescent.
* 7:23 p.m. With the moon higher in the eastern sky now, total eclipse ("totality") begins. The faint copper- or red-colored glow you will notice on the moon is caused by sunlight being refracted (bent) around Earth's upper atmosphere, then inward into Earth's shadow. That light is filtered during its atmospheric passage, so that the predominant colors coming through are red, orange, and yellow. You'll see the faint reddish color much better if you view the moon with binoculars or a small telescope.
* 8:04 p.m. Mid-totality. The moon, high in the east, appears bathed in a deeper and redder glow than seen earlier. The moon is now well inside the darker, inner part of Earth's umbral shadow.
* 8:45 p.m. Totality ends. As viewed with a telescope, the advancing boundary of pure white, direct sunlight across the moon's surface is an interesting spectacle to watch over the ensuing hour or more.
* 9:54 p.m. The closing partial phases end. The moon appears whole, as bright sunlight once again illuminates the entire Earth-facing hemisphere of the moon.
The dark skies of far East County will allow you to better appreciate the fine points of the upcoming eclipse. If you live near the coast and a cloud-laden marine layer threatens to sweep in from the coast, you may have no choice but to travel inland -- probably no farther than Escondido or El Cajon -- in quest of a clear sky.