Did you miss this week's blood moon? Perhaps you weren't equipped for sky gazing in the wee hours on the morning. Maybe you forgot. Or perhaps those pesky clouds hid the red moon from you. If you missed the spectacle or if you just want to see it again, you're in luck. The blood moon will appear three more times before the end of next year.

The April 15 blood moon marked the start of a tetrad, which NASA defines as "a series of four consecutive total eclipses occurring at approximately six month intervals."

"The most unique thing about the 2014-2015 tetrad is that all of them are visible for all or parts of the USA," Fred Espenak, a NASA eclipse expert, said in a NASA blog post.

The blood moon's remarkable color comes as a result of the full moon passing through Earth's shadow. The moon appears a coppery color because of how sunlight from sunsets and sunrises bend through our planet's atmosphere.

"During the 21st century, there are eight sets of tetrads, so I would describe tetrads as a frequent occurrence in the current pattern of lunar eclipses," Espenak continued. "But this has not always been the case. During the three hundred year interval from 1600 to 1900, for instance, there were no tetrads at all."

Some suspect that blood moons represent something apocalyptic, but scientists do not get too excited by the event.

"...It's not the kind of thing astronomers get worked up about," Ed Krupp, director of Los Angeles' Griffith Observatory, said in an interview with CNN. "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."

The next blood moon occurs on Oct. 8. The third and fourth parts of the terad occur on Apr. 4, 2015 and Sept. 28, 2015, respectively. After that, another blood moon won't happen until 2032, so mark your calendars.

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Follow Scharon Harding on Twitter: @SH____4.

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