On This Day in Space! Aug. 18, 1868: Total Solar Eclipse Leads to Discovery of Helium

On Aug. 18, 1868, a French astronomer named Pierre Jules César Janssen discovered helium while observing a total solar eclipse in India. 

During the eclipse, Janssen was using a spectroscope to look at the spectrum of light emitted by the sun. This tool allows scientists to determine what elements they're looking at. While observing solar prominences during the eclipse, Janssen noticed a bright yellow line that didn't correspond to any elements that was not yet discovered on Earth. 

What Is the Sun Made Of?

Atmosphere of the Sun: Photosphere, Chromosphere & Corona

How Hot Is the Sun?

Thirteen years later, the Italian physicist Luigi Palmieri found the first evidence of helium on Earth in the lava of Mount Vesuvius.

Catch up on our entire "On This Day In Space" series on YouTube with this playlist.

On This Day in Space Archive!

Still not enough space? Don't forget to check out our Space Image of the Day, and on the weekends our Best Space Photos and Top Space News Stories of the week

Email Hanneke Weitering at hweitering@space.com or follow her @hannekescience. Follow us @Spacedotcom and on Facebook

Have a news tip, correction or comment? Let us know at community@space.com.