Western Canadians will have the best view early Tuesday morning as the Earth's shadow passes over a full moon, the second total lunar eclipse of the year.

Five months ago when the moon was over the Atlantic Ocean, people in Atlantic Canada, Europe and Africa got to witness the moon turn a dim copper hue.

This time the moon — now over the Pacific — will be viewable in North and South America and eastern Asia, Australia and New Zealand.

An eclipse occurs when the Earth passes between the sun and the moon, blocking the moon from direct light from the sun. It's rare because the moon is usually either above or below the plane of Earth's orbit.

The entire eclipse, as the Earth's shadow creeps across the moon until it totally blocks it, takes about 3½ hours, with the total eclipse lasting about 90 minutes. The moon still gets some sunlight through indirect rays of light refracted through the Earth's atmosphere, and this accounts for the red hue of the moon.

The eclipse will be viewable across Canada, but those in the West will have the longest opportunity to view the moon change colour.

The partial eclipse will begin at 1:51 a.m. PT and end at 5:24 a.m. PT, with the total eclipse beginning at 2:52 a.m. and ending at 4:22 a.m.

Skywatchers in the eastern time zone will only have a brief opportunity to see the total eclipse — which begins at 5:52 a.m. ET — before the sun rises and the moon sets.

The weather forecast across the country calls for mostly clear skies except in Winnipeg, which is expecting cloudy conditions, and Saskatchewan, where possible showers are expected.

The next total lunar eclipse will be Feb. 21, 2008, according to the NASA eclipse home page.