At 400 kilometres up, Earth's gravity is still about 90% of what it is on the ground. Astronauts float because they are constantly falling, along with the station. It moves sideways so fast, about 28,000 km/h, that the Earth keeps curving away beneath it: it falls around the planet without ever hitting it.
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.