On the Earth, helium comes from natural gas deposits in the atmosphere. The atmosphere contains about 5 parts of helium per million parts of air. Helium is a lightweight gas and chemical element and makes up only a small fraction of the Earth's matter. But it is one of the most common elements in the universe. The Sun and other stars are made mostly of helium and hydrogen. The energy of these stars is produced when hydrogen atoms join together to form helium atoms.