How a Medieval Oxford Friar Used Light and Colour to Discover What Stars and Planets Are Made Of

In the 1240s, Richard Fishacre, a Dominican friar at Oxford University, applied his understanding of light and colour to demonstrate that stars and planets consist of the same elements found on Earth. His work challenged the prevailing scientific views of his time and anticipated methods later used by the James Webb space telescope in the 21st century.

Medieval Views on Celestial Composition

Following Aristotle’s ideas, medieval physics held that stars and planets were composed of a unique celestial substance called the “fifth element” or “quintessence.” Unlike Earth’s four elements—fire, water, earth, and air—this fifth element was believed to be perfect, unchanging, and fully transparent. It was thought to form the nine concentric celestial spheres around the Earth, with planets and stars embedded within them.

“The stars and planets were believed to be condensed versions of the 'fifth element', each sphere carrying its own planet, and the outer spheres holding the stars and heaven itself.”

Fishacre’s Challenge to Scientific Orthodoxy

Without the aid of telescopes or rock samples, Fishacre openly disputed the idea that celestial bodies were made from this special element, marking him as the first Dominican friar to teach theology at Oxford University to question such entrenched beliefs.

Summary

Richard Fishacre’s insights on light and colour in the 13th century questioned medieval beliefs about celestial matter, anticipating modern astrophysical discoveries.