In 1868, astronomers studying sunlight, notably during an eclipse, spotted a yellow line that no known element could produce. They named the mystery substance helium, after Helios, the Greek word for the Sun. It took until 1895 for a chemist to finally isolate it on Earth, trapped inside a uranium-bearing mineral.
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.