1 The longest total solar eclipse of the century occurred on July 22 over India, Nepal, Bhutan, and China. It peaked over the Pacific Ocean, but even there the darkness lasted a mere 6 minutes and 29 seconds.
2 Fast and furious: The moon’s shadow zooms across Earth’s surface at up to 5,000 miles per hour.
3 Canadian astronomer and renowned eclipse chaser J. W. Campbell traveled the world for 50 years trying to see 12 different eclipses. He ran into overcast skies every time.
4 Don’t repeat J. W.’s mistakes: Monsoon season throughout south Asia means that there is a good chance the eclipse this July will be clouded out too.
5 Just before full eclipse, dazzling “Baily’s beads” appear where sunlight shines through valleys on the moon. The last bead creates the impression of a diamond ring in the sky.
6 On eclipse-viewing expeditions, this phenomenon is frequently accompanied by a marriage proposal.
7 The beautiful symmetry of a total solar eclipse happens because—by pure chance—the sun is 400 times larger than the moon but is also 400 times farther from Earth, making the two bodies appear the exact same size in the sky.
8 In case you were thinking about relocating: Earth is the only place in the solar system where that happens.
9 Other planets get other kinds of fun, though. Jupiter can have a triple eclipse, in which three moons cast shadows on the planet simultaneously. The event is easily visible through a backyard telescope.
10 The Chinese word for solar eclipse is shih, meaning “to eat.” In ancient China people traditionally beat drums and banged on pots to scare off the “heavenly dog” believed to be devouring the sun.
11 Then again, China also produced the first known astronomical recordings of solar eclipses, inscribed in pieces of bone and shell called “oracle bones,” from around 1050 B.C. or earlier.
12 By comparing those ancient records with modern calculations of eclipse patterns, scientists have determined that the day is 0.047 second longer today than it was back then.
13 Tidal friction, which causes that lengthening of the day, is also making the moon drift away. In about 600 million years it will appear too small to cover the sun, and there will be no more total solar eclipses.
14 In any given location, a total solar eclipse happens just once every 360 years on average.
15 Luckiest place on Earth Carbondale, Illinois, will beat the odds: Folks there will see an eclipse on August 21, 2017, and again on April 8, 2024.
16 In contrast, everyone on the night side of the world can see a lunar eclipse, where the moon slips into Earth’s shadow.
17 During a total lunar eclipse, the moon takes on a deep reddish hue due to the sunlight filtering through our atmosphere—the cumulative glow of all the world’s sunsets.
18 While stranded in Jamaica, Christopher Columbus was famously saved by the lunar eclipse of February 29, 1504, which he had read about in his almanac. After a fracas with the locals, Columbus warned that the moon would disappear if they did not start supplying his men with food.
19 When the moon vanished, the locals promptly complied, and Columbus breathed a huge sigh of relief: His almanac was calibrated for Germany, and he was not sure that he had adjusted correctly for local time.
20 Who knows—it might be useful to you, too. The next lunar eclipse visible from the United States will take place on December 21, 2010.