'Blood moon' sweeps night sky

Updated 8:15 AM ET, Sat April 4, 2015
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A "blood moon" rises over the El Salvador del Mundo monument in San Salvador early Tuesday, April 15, 2014, as a total lunar eclipse attracts sky gazers across the Americas. In a total lunar eclipse, the full moon turns a coppery red as it passes into Earth's shadow. "It's like seeing all the sunsets on Earth projected on the moon at once," says Indra Petersons of CNN's "New Day." JOSE CABEZAS/AFP/Getty Images
The moon is seen from Miami before the beginning of the total lunar eclipse. The blood moon was most prominent in North and South America. Joe Raedle/Getty Images
Another shot from Miami. Showers and clouds rendered viewing the blood moon a bust in some U.S. cities. Joe Raedle/Getty Images
Dust and sulfur dioxide in the Earth's atmosphere can affect the size of the shadow spreading across the moon's surface. Joe Raedle/Getty Images
The moon has to be full for the total lunar eclipse to occur. Joe Raedle/Getty Images
The Earth's shadow crosses over the last bit of reflected light on the moon's surface. Joe Raedle/Getty Images
The moon begins to take on a reddish hue early Tuesday from Miami. The moon did so as it appeared in different phases between 2 and 4:30 a.m. ET. Joe Raedle/Getty Images
The red hue is caused by refracted sunlight in the Earth's atmosphere, which bounces off the moon while in shadow. The entire reddening process takes about an hour. Joe Raedle/Getty Images
The total lunar eclipse is seen in this image taken from Miami. Unlike solar eclipses, lunar eclipses are safe to view with the naked eye and don't require special filters. Joe Raedle/Getty Images
A lunar eclipse takes place over Southern California early Tuesday as seen from the San Gabriel Valley. North America will see a blood moon four times -- known as a tetrad -- between now and September 2015. FREDERIC J. BROWN/AFP/Getty Images