Helium is named after ‘Helios’, the Sun God, because its optical spectrum was discovered by measurements of the sun’s corona. Everyone knows that helium is used for inflating party balloons and these will float away if you let go. Incidentally there is an interesting experiments that can be done with a helium balloon inside a car: just hold it by its string, not letting it touch the roof, and watch what it does as you go around corners, brake, or accelerate.