A total lunar eclipse will turn the moon blood red on Tuesday across several continents

Solar and lunar eclipses happen due to a precise alignment of the sun, moon and Earth. There are between four and seven a year, according to NASA.

The eclipses tend to follow each other, taking advantage of the sweet spot in the celestial bodies' orbits. Tuesday's total eclipse of the moon comes two weeks after a ‘ring of fire’ solar eclipse that dazzled people and penguins in Antarctica.

During a total lunar eclipse, the Earth is between the sun and full moon, casting a shadow that covers the moon. The so-called blood moon looks red because of stray bits of sunlight filtering through Earth's atmosphere.

The show unfolds over several hours, with totality lasting about an hour.

Compared to a solar eclipse, “the lunar eclipse is a little more of a relaxed pace,” said Catherine Miller at Middlebury College's Mittelman Observatory.

For those in the path, there's no need for any special equipment to observe — just a clear, cloudless view of the sky.

Use a forecasting app or any online celestial calendar to look up the exact timing for your area. Venture outside a few times to see Earth's shadow darken the moon, eventually revealing the reddish-orange orb.

“You don’t have to be out there the whole time to see the shadows moving,” said astronomer Bennett Maruca with the University of Delaware.

There's a partial lunar eclipse on the docket for August, visible across the Americas, Europe, Africa and west Asia.

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