WASHINGTON, D.C.—Dedicated joggers and diehard sky-watchers across much of North America enjoyed a total lunar eclipse early this morning. In the U.S. capital the eclipse, also referred to as a blood moon, turned the ghostly orb a dusky orange before the rising sun obliterated the view.

The total eclipse was the second in a series of four that began in April and will end next September. Such consecutive total eclipses, known as a tetrad, are relatively rare. Only seven more will happen in this century.

Those who miss the current tetrad will have to wait about 20 years for the next one.

Early Risers

The event was special enough to Gustavo Shong and Olesia Kavulych of Springfield, Virginia, that it got them out of bed and onto the National Mall at around 5 a.m. Shong thought more people would be out to view the eclipse, but he and Kavulych had the stretch of grass between the Capitol building and the Washington Monument almost to themselves.

It was Kavulych's first lunar eclipse. "It's beautiful," she said.

She wasn't the only one enjoying her first lunar eclipse. Alex Gorski's father had called the 27-year-old Washington, D.C., resident at 5:30 a.m. to make sure he got out to see the blood moon. "I missed the first one [in April]," Gorski said, "so I wanted to catch this one."

Moon Monikers

The first eclipse in the current tetrad occurred overnight, beginning on April 14 and ending on April 15. The third will happen on April 4, 2015; the last will grace North American skies on September 28, 2015. (See "Lunar Eclipse Myths From Around the World.")

Adding to the tetrad's appeal is the fact that total lunar eclipses can shift the color of the moon dramatically, from a light rusty orange to blood red or even black. The darker hues inspired the "blood moon" moniker.

During an eclipse, the sun, Earth, and moon align in such a way that the lunar orb slips into Earth's shadow. Some sunlight does leak around Earth's periphery, filtering through its atmosphere and reflecting off the moon.

The amount of dust and pollution peppering the atmosphere determines the exact color of the moon during the eclipse. The more dust—say from volcanic eruptions—the darker the red light cast on the moon.

There's no way to tell what color the moon will turn in advance. You just have to watch and enjoy.

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