00:01On this day in space.
00:03In 1868, a French astronomer named Pierre-Jules César Janssen discovered helium while observing a total solar eclipse in India.
00:10During the eclipse, Janssen was using a spectroscope to look at the spectrum of light emitted by the sun.
00:15This tool allows scientists to determine what elements they're looking at.
00:18While observing solar prominences during the eclipse, Janssen noticed a bright yellow line that didn't correspond to any elements that had been discovered on Earth.
00:25Thirteen years later, the Italian physicist Luigi Palmieri found the first evidence of helium on Earth in the lava of Mount Vesuvius.
00:32And that's what happened on this day in space.
