Helium was named after Helios, the Greek name for the Sun.
The element received its name because it was first detected in the Sun’s spectrum rather than on Earth. During the 1868 solar eclipse, the French astronomer Jules Janssen and the English astronomer Norman Lockyer independently observed an unfamiliar yellow spectral line. Lockyer proposed that it came from a previously unknown element and named it helium.
Helium was later isolated on Earth in 1895 by the Scottish chemist William Ramsay, working with minerals containing uranium. The gas is chemically very unreactive because its electron shell is complete, making helium the least reactive of the noble gases in ordinary conditions.
Helium is the second-lightest element after hydrogen. It is widely used in cryogenics, scientific instruments, leak detection, and lighter-than-air balloons. Tellurium’s name also relates to astronomy, but it comes from the Latin word for Earth, tellus, not from Helios.