Finding the noble gases played out like a detective story:

• 1868 — astronomer Pierre Janssen spots an unknown spectral line in sunlight during an eclipse. It is named helium (from helios, Greek for sun), an element found in space before it was found on Earth
• 1894 — Lord Rayleigh notices that nitrogen from air is denser than nitrogen from chemicals. William Ramsay isolates the mystery component: argon, meaning "the lazy one"
• 1898 — Ramsay and Morris Travers discover neon ("new"), krypton ("hidden"), and xenon ("stranger") in quick succession by distilling liquid air
• 1900 — Friedrich Dorn discovers radon as a radioactive decay product of radium