Helium was discovered on the sun in 1868, almost 30 years before it was discovered he on earth. How could that be possible?
The scientist were able to detect Helium from its absorption spectrum.
Every element has a unique spectrum of light energy lines based on its electron configuration.
In studying the sun unique dark lines were observed that didn't match any known elements on earth.
The scientists knew that they had discovered evidence of a new element. The element was name Helium after the Greek word for the sun.
Scientists can get clues about what elements are present in distant stars by studying the spectra of the stars.