Gallium is a silvery metal, solid at room temperature, yet it melts at 29.8 °C. Held in your hand, it slowly turns into a shiny puddle. Pranksters make gallium spoons that vanish when stirred into hot tea. More seriously, this metal is a key ingredient in LEDs and computer chips.
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.