(1) Helium is the second most abundant element in the universe.
(2) In 1928 helium became available on the open market for the first time.
(3) Helium is so light that Earth’s gravity is not strong enough to hold on to it. When helium atoms are released into the atmosphere, they rise until they escape into space.
(4) Helium is one of only two natural elements that has never been observed bonding to another element in a compound. The other element is neon. Helium plasma can, however, form temporary excimer molecules with elements including sodium, fluorine and sulfur.
(5) At temperatures close to absolute zero helium condenses to a liquid with amazing properties – the properties of a superfluid, flowing with zero friction up and over the walls of containers.
(6) At normal atmospheric pressure helium does not solidify. At 25 atmospheres of pressure helium is a solid at 0.95 K. As the pressure rises, the temperature at which solid helium exists also rises. Helium can be made solid at room temperature if the pressure rises to about 114 thousand atmospheres: that is a pressure of 1.67 million psi, or 834 tons per square inch. This is over 100 times greater than the pressure at the oceans’ deepest point, the Challenger Deep, which is almost seven miles deep (10,916 meters).