Set that alarm Tuesday. The partial eclipse starts at 1:51 a.m. The total eclipse starts at 2:52 a.m. and ends at 4:22 a.m.

DENVER — The Earth’s shadow will creep across the moon’s surface early Tuesday, slowly eclipsing it and turning it to shades of orange and red.

And skywatchers in the West will have a front-row seat: The total lunar eclipse will be especially visible here. People in South America, other parts of North America, the Pacific islands, eastern Asia, Australia and New Zealand also will be able to view it if skies are clear.

Skies are expected to be clear in the Seattle area during the eclipse.

There’s no need to leave the city to see the event, said Tim McKechnie of the Seattle Astronomical Society. The moon will be due south, about 45 degrees above the horizon, when the partial eclipse starts at 1:51 a.m. The total eclipse starts at 2:52 a.m. and ends at 4:22 a.m. The partial eclipse ends at 5:24 a.m.

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The eclipse is the second this year. People in Europe, Africa or the Middle East, who had the best view of the last total lunar eclipse in March, won’t see this one because the moon will have set there when the partial eclipse begins.

An eclipse occurs when Earth passes between the sun and the moon, blocking the sun’s light. The relative positions of the Earth and the moon make this a rare event.

Because the Earth is bigger than the moon, the process of the Earth’s shadow taking a bigger and bigger “bite” out of the moon, totally eclipsing it before the shadow recedes, lasts about 3 ½ hours, said Doug Duncan, director of the University of Colorado’s Fiske Planetarium. The total eclipse phase, in which the moon has an orange or reddish glow, lasts about 1 ½ hours.

The full eclipse will be visible across the United States, but East Coast viewers will only have about a half-hour to see it before the sun begins to rise and the moon sets. Skywatchers in the West will get the full show. In eastern Asia, the moon will rise in various stages of eclipse.

During the full eclipse, the moon won’t be completely dark because some light still reaches it around the edges of the Earth.

The next total lunar eclipse occurs Feb. 21, 2008, and will be visible from the Americas, Europe and Asia.

Seattle Times staff reporter David Heath contributed to this report.