Discovery of Helium

Date: August 18, 1868 • Location: Paris, France

French astronomer Pierre Janssen discovers helium.

An astronomer is a scientist in the field of astronomy who focuses on a specific question or field outside the scope of Earth. Astronomers study astronomical objects, such as stars, planets, moons, comets and galaxies, by some combination of observation and the application of astrophysical models. Examples of topics or fields astronomers study include planetary science, solar astronomy, the origin or evolution of stars, or the formation of galaxies. A related but distinct subject is physical cosmology, which studies the universe as a whole.