Helium

Uses

Liquid helium’s defining use is as a coolant for superconducting magnets, most notably in MRI scanners, where it chills the magnet coils to temperatures cold enough for superconductivity to work. That same extreme-cold capability makes it valuable in scientific research, including particle accelerators and low-temperature physics experiments. Because it’s inert and won’t react with molten or reactive metals, helium is also used as a protective shielding gas in some types of welding.

Its low density and non-flammability make it the standard gas for balloons and airships, and deep-sea divers sometimes breathe a helium-oxygen mixture called heliox, which reduces the risk of nitrogen-related problems at depth compared to ordinary compressed air.

History

Helium was first detected in 1868, not in a laboratory but in the Sun. During a solar eclipse, French astronomer Pierre Janssen observed a bright yellow line in the Sun’s spectrum that didn’t match any known element, and English astronomer Norman Lockyer, studying the same spectral feature separately, proposed it belonged to a new element and named it helium, after Helios, the Greek sun god. It wasn’t confirmed on Earth until 1895, when Scottish chemist William Ramsay isolated it from a uranium-bearing mineral, showing that this “solar” element existed here all along.