'Blood moon' dazzles skywatchers around the world

The longest total lunar eclipse of the 21st century occured on Friday, July 27, and was visible from much of the world.

Prime viewing locations for the four-hour long event included Cairo, Egypt; Santorini, Greece; and Harare, Zimbabwe.

Here are some of the best views of the spectacular show in the sky.

For those who are confused: A total lunar eclipse occurs when the earth passes directly between the sun and moon, making the moon fall into shadow. This phenomenon also causes what’s commonly called a “blood moon” because of the reddish glow the moon appears to emit during sunset and sunrise. Here's a look at it from the Temple of Poseidon in Athens, Greece. Photograph: Alkis Konstantinidis/Reuters

The lunar eclipse lasted for one hour and 43 minutes, just shy of the longest possible totality: one hour and 47 minutes, according to Time. The rare spectacle seen behind The Hohenzollern Castle, the ancestral seat of the Prussian Royal House and of the Hohenzollern Princes, in Hechingen, Germany. Photograph: Matthias Hangst/Getty Images

It began in Australia and Indonesia, and it moved across the globe. North America, much of the Pacific Ocean and most of the Arctic didn't see a thing. The entire United States won't be able to see a full lunar eclipse again until January. People in Abu Dhabi were lucky as they got to see it playing hide-and-seek behind the Sheikh Zayed Grand Mosque. Photograph: Christopher Pike/Reuters

The red moon had some company when Mars was the closest it's been to Earth in 15 years. Photograph: Muhammad Hamed/Reuters

Unlike a solar eclipse – where the moon crosses in between the Earth and the sun – it is perfectly safe to look directly at the Blood Moon without sunglasses or protective eyewear. The moon in all its glory behind the statue of ancient Athena goddess in Athens, Greece. Photograph: Costas Baltas/Reuters

The Blood Moon will be the most impressive of the 21st century, with the best one in the 20th century taking place right at the very end - on July 16 2000, lasting for one hour and 46 minutes. Photograph: Michael Dalder/Reuters

A man tries to take a selfie with the moon during the longest lunar eclipse of the 21st Century, in Rio de Janeiro, Brazil. Photograph: Pilar Olivares/Reuters