Eclipse cycle
The saros is a measurement of time equal to 6585 days (plus one third of a day). It is the time between identical eclipses.
Natural nuclear power
Enrico Fermi switched on the first human-made nuclear reactor in 1942, but the first natural nuclear reactor on Earth occurred 1.7 billion years earlier.
The death of Tycho Brahe
The body of famed astronomer Tycho Brahe was dug up twice (in 1901 and 2010) to find out what killed him. The conclusion: he died of excessive politeness.
Lunar garbage collection
The second mission to land on the Moon had garbage collection duty: they picked up the remains of a probe that had crashed there two years earlier.
Oldest Earth rock
The oldest Earth rock was not found on the Earth.
Da Vinci and Machiavelli steal a river
Leonardo da Vinci and Niccolò Machiavelli once teamed up to steal the Arno river.
Punch a hole in the sky
Aircraft can punch cloud holes that are much larger than the plane itself.
Rubble moon
The Martian moon Phobos is thought to be a pile of rubble that’s nearly a third empty space inside. It circles its planet twice a Martian day, and in a few million years it will disintegrate into rings.
Dam the Mediterranean
In 1929 Bavarian architect Herman Sörgel proposed building a dam across the Strait of Gibraltar and shrinking the Mediterranean.
Hand-woven memory
The Apollo Guidance Computer used core rope memory; the software was literally woven by hand into it.
Cities at the bottom of the sea
423,000 people live in Flevoland, a province of the Netherlands. Before 1957, the entire area did not exist.
The sun after sunset
Where can you see sunlight after the sun has set? In the zodiac or sometimes directly opposite the sun in the night sky.
The nearest planet
What’s the nearest planet to Earth? On average, it’s Mercury. What’s the nearest planet to Venus, Mars, Jupiter, Saturn, Uranus, and Neptune? Also Mercury.
The Amazon, reversed
The rise of the Andes reversed the direction of the Amazon River’s flow from the Pacific to the Atlantic.
Extreme heat
The Danakil Depression in the Afar Triangle, Ethiopia, is the point where three tectonic plates diverge; has the highest average annual temperature on the planet; and Lucy, the Australopithecus fossil, was found there.
