As it fuses hydrogen, the Sun pumps out neutrinos in staggering numbers. About 60 billion of them cross each square centimeter of your skin every second, day and night, because the Earth does not stop them. They almost never interact: even a wall of lead a light-year thick would let a good share of them through.
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.