The nautical mile, set at 1,852 metres, roughly matches one minute of arc of latitude, a sixtieth of a degree along a meridian. On a chart, you can measure distances just by reading the latitude scale. The knot, the speed unit of ships and aircraft, is one nautical mile per hour, named after the knots of a rope once tossed overboard.
Cooled below −183 °C, oxygen turns into a pale blue liquid. Pour it between the poles of a strong magnet and, instead of flowing away, it hangs suspended between them. The reason lies in its unpaired electrons, which respond to the magnetic field. Liquid nitrogen, by contrast, is colourless and pours straight through.
In 2012, Felix Baumgartner jumped from a capsule hanging beneath a balloon, about 39 kilometres up. In that extremely thin air almost nothing slowed him down, and he reached around 1,358 km/h in free fall, or Mach 1.25. He became the first person to exceed the speed of sound with nothing but his own body.