Watch for lunar eclipse on Wednesday

Mother Nature is playing both hero and villain in a drama shaping up around a total lunar eclipse Wednesday that should, for once, be visible at a civilized hour — unless it rains.

The event — the last total lunar eclipse until Dec. 21, 2010 — will begin as the sun is setting Wednesday and reach totality from 7:01 to 7:51 p.m., comfortably after dinner.

But eager astronomers who’ve been making plans to watch the show have been fretting over recent weather forecasts that were looking especially discouraging.

Weather forecasts being what they are — sometimes inaccurate — moon watchers are going forward with their plans, at least for the moment.

“We’re going to play it by ear on that,” said Sonoma County Regional Park Marketing Coordinator Donna LaGraffe, who has about 85 people signed up to view the eclipse after a short trek at Helen Putnam Regional Park just outside Petaluma.

A downpour will probably cancel the hike, she said, but drizzle should mean it goes ahead.

“If there’s even a possibility of seeing it, we’ll probably just go, and we’ll see which hearty souls get out and join us,” LaGraffe said.

Santa Rosa Junior College Planetarium Director Ed Megill will lend his enthusiasm for all things inter-planetary during the Helen Putnam viewing, which he’ll M.C.

“Hopefully, they’re just not that good at forecasting,” Megill said of the prospects for bad weather.

A lunar eclipse occurs when the earth, moon and sun align in such a way that the earth is in between the other two, blocking the sun’s rays from reaching and reflecting off the moon. The moon must be full.

On each end of the total eclipse, the moon passes through a partial shadow of the earth, causing a partial eclipse, and then slips into the complete shadow of the earth, creating a total eclipse.

“It will be this beautiful rusty red color,” Megill said, referring the the coloring that results from indirect sunlight filtered through the earth’s atmosphere.

The moon will rise in the east just as the sun sets in the west, with the eclipse beginning at 5:43 p.m., 11 minutes before sunset.

The eclipse will be total from 7:01 to 7:51 p.m., with the moon at the center of the earth’s shadow at 7:26 p.m.

The moon then will shift back into partial eclipse until 9:09 p.m.

The eclipse will occur as the moon moves just above the horizon and will be at just 20 degrees when is it full and at its most beautiful, Megill said.

Anyone wanting to see it will have to have a clear view to the east, perhaps from a knoll or hillside with an unobstructed view of the horizon.

That’s why Helen Putnam proved a suitable viewing location, providing a board knoll about a quarter mile down a paved road, LaGraffe said.

The Robert Ferguson Observatory at Sugarloaf State Park also is hosting a viewing beginning at 5 p.m. Wednesday. The price is $3. Admission is free for those under 18.

Helen Putnam Park hikers, including any latecomers who decide to join if the weather allows, are to meet at 6:30 p.m. at the trailhead off the Oxford Court entrance on the parks’ northeast boundary.

Free parking and a free shuttle ride from the park’s Chileno Valley Road entrance will be available.

Warm clothing, binoculars and/or a camera, water and food are recommended.

Interested parties can call the park office at 565-2041 Wednesday afternoon to check on the status of the outing.

You can reach Staff Writer Mary Callahan at 521-5249 or mary.callahan@pressdemocrat.com.