Pilots had reported them for years, but a sprite was first caught on camera, almost by accident, only in 1989. These reddish flashes, shaped like jellyfish or carrots, burst 50 to 90 km up above powerful storms and last just a few milliseconds. They belong to a family of upper-atmosphere light shows that also includes blue jets and 'elves'.
On 27 August 1883, the eruption of the Indonesian volcano Krakatoa was heard as far away as Rodrigues Island, nearly 4,800 km away. Its pressure wave was picked up by barometers worldwide and circled the globe several times. The tsunamis that followed killed more than 36,000 people.
The deepest known point in the ocean, Challenger Deep, lies roughly 10,900 m below the Pacific surface. Drop Everest in and its summit would still sit about 2 km underwater. Down there, the pressure is more than 1,000 times what you feel at sea level, roughly a tonne pressing on every square centimetre.