The medieval Oxford friar who worked out the makeup of planets and stars | Science

AAbout 800 years ago, Richard Fishacre, a Dominican friar at Oxford University, challenged the scientific thinking of the time, using his understanding of the behavior of light to show that stars and planets are made of the same elements found on Earth. Although he was heavily criticized at the time, Fishacre would probably have been delighted to learn that very similar principles are used to make discoveries today.

During his lifetime, Earth was believed to be made up of four elements – fire, water, earth and air – while the stars and other planets were made up of a special fifth element, transparent and unchanging.

But Fishacre drew on his understanding of light and color to argue that if the stars and planets were made of such a substance, they would appear transparent. Instead, the red of Mars, the yellow of Venus and the blue and white of the Moon, he said, were clear evidence that they were made of multiple elements also found on Earth.

Today, telescopes such as James Webb detect variations in the brightness and color of light from distant planets and stars, recently revealing that TOI-421b – an exoplanet about 244 light-years away – has an atmosphere rich in water and sulfur dioxide.