Step outside, gaze upward and catch a glimpse of a coppery red moon crossing the Earth's shadow.
The so-called "blood moon" is gracing the skies in different phases between 2 a.m. ET and 4:30 a.m. ET.
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In Los Angeles, the chance to view the total lunar eclipse lured thousands to the Griffith Observatory. Families spread out blankets on the grass to take in views from dozens of telescopes set up like a stand of small trees.
"It's energizing. Look around. Everybody is here to see something
rare and live," said Gene Ireland, who teaches astronomy to middle school students.
And for a moment, albeit briefly, eyeballs were turned upward.
Ireland encouraged those who reached the hilltop observatory grounds to peek through his 12-inch Dobsonian reflector telescope.
"Everyone is always looking down at their phones, their iPads," he said. "We want them looking up. Looking up, you see a whole different world. Getting away from the cities and traffic and the sky is just beautiful."
Ed Krupp, director of the observatory, described it as a " typical copper red" total lunar eclipse.
Though rare, it's the sky "conspiring into a special event" that draws crowds, he said.
"The fact that there are four lunar successions coming this year and next ... is unusual," Krupp said. "But it's not the kind of thing astronomers get worked up about . It doesn't really mean anything. It's a chance arrangement of gravity and the motions of objects in the solar system, primarily the Earth and moon."
If you miss it Tuesday, there will be more opportunities.
It's the first in a series of four consecutive total lunar eclipses known as the tetrad. The phenomenon will repeat itself three more times in six-month intervals ending in September 2015.
Miss those, and you'll have to wait until 2032--33.
In a total lunar eclipse, the moon gets a red sheen as it passes behind the Earth into its umbra (shadow).
"Since Earth's umbral shadow is darker in the center than at the edge, the moon's appearance will likely change dramatically with time as the total phase progresses," NASA said in a statement.
The blood moon starts to change from its silver color as it slides into the Earth's shadow, NASA said.
It becomes a "blood moon" at 3:07 a.m. ET, with the best part of the show -- the total eclipse portion -- lasting through 4:24 a.m. ET.
Potential viewers in some parts of the eastern United States will be at the mercy of the cloud cover, which is expected to hide the show from half of the country.
But cities such as Dallas, Denver and Los Angeles should have optimal, front-row seats
People in the Americas will watch the entire spectacle while observers in the western Pacific will catch the second half of the event, NASA said. Europe and Africa won't see much -- the moon will be setting in most of those continents during the eclipse.
North Americas will see a blood moon a total of four times Tuesday and October 8 this year, and April 4 and September 28 next year.
Unlike solar eclipses, lunar eclipses are safe to view with the naked eye. No special filters are required to safeguard your eyes.
Blood moon timeline
12:53 a.m. ET -- The eclipse will officially begin but there will not yet be anything to see with the human eye.
1:40 a.m. ET -- Observers should start to see some partial darkening along the left edge of the moon that will increase as the minutes pass.
1:58 a.m. ET -- Partial eclipse begins: People will start to see the dark disk of the Earth's shadow crossing the moon. The shadow will advance across the moon throughout the next hour.
2:50 a.m. ET -- As more of the moon becomes covered in shadow, observers should start to see parts of the dark shadow turn dark red or orange.
3:06 a.m. ET -- Total eclipse begins with the moon completely in the shadow of the Earth and should appear reddish orange. The blood moon has arrived.
3:45 a.m. ET -- Great eclipse: The middle of the total eclipse; moon should appear dark red/orange
4:24 a.m. ET -- Total eclipse ends: Moon will begin to reappear from the shadow and coloration will begin to disappear.
4:45 a.m. ET - As more of the moon emerges from the shadow, the color should be mostly gone. What is left will appear black.
5:33 a.m. ET -- Partial eclipse ends as dark shadow completely leaves the moon, which will return to its normal look over the next 10-20 minutes.
6:37 a.m. ET -- Eclipse officially ends./CNN/