Alexander Fleming was a Scottish microbiologist, pharmacologist, and pathologist who discovered the antibiotic substance penicillin in 1928.

Astronomy is a natural science that studies celestial objects, such as stars, planets, comets, and galaxies, as well as the phenomena and processes that occur in outer space.

Henrietta Swan Leavitt (July 4, 1868 - December 12, 1921) was an American astronomer.

Hydrogen is a chemical element with the symbol H and atomic number 1.

The Mount Wilson Observatory (MWO) is an astronomical observatory in Los Angeles County, California, United States.

The Royal Astronomical Society (RAS) is a learned society and charity that encourages and promotes the study of astronomy, solar-system science, geophysics and closely related branches of science.