The next time this will happen will be in 2019, NASA says.
So get out and take a look because the skies will be relatively clear for tonight's "blood red" lunar eclipse, says NASA and the National Weather Service.
According to a NASA statement, the full eclipse will appear to change the color of the moon from its usual milky appearance to something more sinister:
... The public will get a spectacular view looking into the sky as the moon's appearance will change from bright orange to blood red to dark brown and perhaps gray. The eclipse is a phenomenon that occurs when the Earth, moon and sun are in perfect alignment, blanketing the moon in the Earth's shadow. The United States will not be able to witness a full lunar eclipse in its entirety again until 2019.
Starting at 10:58 p.m. tonight the earth's shadow will begin to take a bite out of the moon, according to the Griffith Observatory.
At 12:06 a.m. that shadow will have completely covered the moon, the Observatory says. The full eclipse will be ongoing through 1:25 a.m., with the greatest coverage of the moon peaking at 12:46 a.m., Griffith experts say.
What will happen during that eclipse is fascinating. Michelle Thaller of NASA says "it's a beautiful thing."
"The only sunlight reaching the moon is light that's being scattered through the atmosphere ... [which] lets red light through in a more direct manner," she said.
The Griffith Observatory seconds that emotion, explaining:
... It usually glows with a faint copper or red color, a result of sunlight being filtered and bent through the Earth's atmosphere (much like a sunset). The lunar eclipse is visible throughout southern California and can be seen easily with the unaided eye, though telescopes or binoculars may enhance the view.
National Weather Service meteorologist Kathy Hoxsie told us that viewing should be prime. Only 10 to 20 percent cloud cover was expected along the coast and inland in the L.A. Basin, with low temperatures mostly in the mid-50s, she said.
If you don't want to stand out on the sidewalk, Griffith Observatory is the place to be.
Eclipse-watching festivities begin at 7 p.m. and include free use of telescopes, commentary by experts and late hours for the cafe and bookstore, which won't close until 2 a.m.
Organizers expect crowds and parking could be an issue. For that reason a shuttle will be running from the Greek Theater lot to the Observatory.
[Added at 3:06 p.m.]: Edwin Krupp, director of the Observatory, says you're going to be looking south and about halfway up the sky tonight.
And you'll get a bonus, he says, because Mars will making its closest orbital pass to earth about the same time.
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"It looks like a bright star to the upper right of the moon," he told us. "Mars is the red planet, it has a tinge of red. So you'll be seeing two red objects."
If you're glued to your computer, tablet or smartphone and can't get out, Griffith Observatory will be streaming the eclipse.
[Added at 3:55 p.m.]: By the way, Krupp says pretty much all full lunar eclipse's make the moon look red. There's nothing particularly unique about this one except that, like we said, the next one is five years away.