Celestial trifecta: Full moon, lunar eclipse, comet starring in night skies this weekend

SEATTLE -- A full moon and comet share double billing in a special night sky show this weekend.

A lunar eclipse starts everything off Friday night. The moon will pass into Earth's outer shadow, or penumbra. The moon won't be blacked out like in a full eclipse. Only part of the moon will be shaded, but it should be easily visible from much of the world.

In Seattle, we're not in the best spot in the world to see it, but we'll catch a quick glimpse, weather permitting. The moon will rise at 5:28 p.m. just 3 minutes before the eclipse reaches maximum, but the moon will still be just on to barely under the horizon, so we'll miss the maximum part, but it will continue to rise partially eclipsed until the eclipse ends at 6:53 p.m. Bonus for photographers: It'll still be a full moon when the eclipse ends, making for typical dramatic photos around the region.

The weather around Western Washington Friday night is looking about 50/50 for clouds. It's not looking like a total overcast, but still plenty of clouds roaming around in the wake of Wednesday and Thursday's storm. Still, should at least get a peek of the moon at some point between the clouds.

Then, be sure to be up early Saturday to catch Comet 45P, which will zoom past Earth early Saturday morning. It will be an extremely close encounter as these things go, passing within 7.7 million miles (12.4 million kilometers) of Earth. Its relative speed: 14.2 miles per second, or a breakneck 51,120 mph.

The comet will be officially visible in the constellation Hercules. In Seattle, that is low in the northeastern sky around midnight and then will rise higher toward due east as the night progresses. But it's going to be tough to see.

For one, it's really dim. You'll need at least binoculars, or better yet, a telescope to aid in the search. It'll appear as a tiny green smudge -- this is not the glowing-streak-in-the-sky like Swift-Tuttle or Hyakutake. The "peak" time in Seattle to spot it is around midnight Saturday morning when the comet makes its closest approach, but you'll be able to see it, such as it is, through the night.

But aside from it being quite dim, you'll have two other challenges to find the spot: Clouds will take up about half the sky so have to hope they clear out the right area, and as we just mentioned a few paragraphs ago, it'll be a full moon. Great for eclipses; bad for celestial viewing with its bright flashlight effect washing out some of the dim objects in the sky. Special third challenge for anyone within an hour's drive of Seattle: City lights also wash out the sky. Get thee somewhere where you can see a lot of stars.

Stargazers have been tracking Comet 45P for the past couple of months. The ice ball - an estimated mile across - comes around every five years. It's officially known as Comet 45P/Honda-Mrkos-Pajdusakova, named after the Japanese, Czech and Slovak astronomers who discovered it in 1948. The letter P stands for periodic, meaning it's a recurring visitor to the inner solar system.

The Slooh network of observatories will provide a live broadcast from the Canary Islands for both big events.

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