Ever wonder where the name of the element helium comes from? Yeah, me neither. But if we had, it likely would've occurred to us that the name is not unlike the Greek name for the Sun, helios, but it would still leave unanswered the question of "Why?" Well, it turns out that's where helium was first discovered--93 million miles away, on the Sun. Crazy, right?
On August 18, 1868, French astronomer Pierre Janssen was in British India, using a spectroscope to see the solar prominences (little curlicues flares of cool plasma) emitted from the Sun during an eclipse. While doing so, he noticed a thin yellow line, one never before seen, with a wavelength of 587.49 nm. Dude had discovered helium and he didn't even know it.
Two months later, Joseph Norman Lockyer set up in England a new, more powerful spectrometer to see for himself what was up. He first thought it might be a new form of hydrogen, but experiments proved otherwise, so he decided it must be some new kind of element, which he assumed was a metal, and named it helium, "-ium" being the scientific suffix of choice for minerals.
It would be another 27 years, in 1895, before Swedes Per Teodor Cleve and Nils Abraham Langer confirmed helium's presence here on Earth, and were able to measure its atomic weight.