Centuries before Carl Sagan popularized “we are made of star‑stuff,” 13th‑century Dominican Richard Fishacre used observations of color and eclipses to argue that celestial bodies share material composition with Earth. Fishacre challenged Aristotle’s notion of a separate celestial element by noting that Mars and Venus display terrestrial hues and that the moon can block the sun, implying it is opaque and made of substance like earthly matter. Modern methods—such as JWST transmission spectroscopy detecting water and sulfur dioxide on TOI‑421 b—broadly vindicate the idea that terrestrial and celestial materials are related, though Fishacre’s approach was philosophical rather than chemical.
How a 13th‑Century Friar Anticipated Carl Sagan’s 'We Are Made of Star‑Stuff'
Centuries before Carl Sagan popularized “we are made of star‑stuff,” 13th‑century Dominican Richard Fishacre used observations of color and eclipses to argue that celestial bodies share material composition with Earth. Fishacre challenged Aristotle’s notion of a separate celestial element by noting that Mars and Venus display terrestrial hues and that the moon can block the sun, implying it is opaque and made of substance like earthly matter. Modern methods—such as JWST transmission spectroscopy detecting water and sulfur dioxide on TOI‑421 b—broadly vindicate the idea that terrestrial and celestial materials are related, though Fishacre’s approach was philosophical rather than chemical.
01:21 PM, 11/18/2025Science
How a 13th‑Century Friar Anticipated Carl Sagan’s 'We Are Made of Star‑Stuff'
We are made of star‑stuff. Carl Sagan’s famous line from his 1980 series Cosmos captured a scientific truth in a poetic phrase: many of the chemical elements in our bodies were forged inside stars. But a related idea—linking earthly matter with the material of the heavens—appears centuries earlier in the thinking of a medieval theologian.
“The cosmos is within us. We are made of star stuff.” — Carl Sagan
In the 1240s, the Dominican theologian and philosopher Richard Fishacre argued, from careful observation of color and light, that planets and stars are composed of the same kinds of material found on Earth. His view challenged the prevailing Aristotelian cosmology, which held that the heavens were made of a perfect, immutable fifth element distinct from the four terrestrial elements—earth, water, air and fire.
Fishacre drew on naked‑eye observations. He noted that Mars often appears faintly red and Venus yellowish, hues he associated with opaque, terrestrial substances. Most compelling to him was the moon’s behavior during eclipses: because the moon can block the sun, he reasoned, it cannot be a perfectly transparent, glass‑like medium but must be made of physical substance and governed by the same natural laws as earthly matter. From these visual and logical inferences, he concluded that the gap between heaven and Earth was smaller than many contemporaries assumed.
Fishacre became the first Dominican to teach theology at Oxford and faced criticism for some of his ideas. His arguments were philosophical and phenomenological rather than chemical or quantitative—he lacked modern instruments and the language of atomic theory—but they anticipate a pattern of thought that modern astronomy has since confirmed: that celestial bodies share chemical kinship with Earth.
Recent observations illustrate how far the methods have advanced. Using the James Webb Space Telescope, astronomers identified water and sulfur dioxide in the atmosphere of a Neptune‑like exoplanet, TOI‑421 b, roughly 244 million light‑years away. That identification relied on transmission spectroscopy, which detects subtle color and light variations in starlight filtered through a planet’s atmosphere to infer molecular constituents—an instrument‑driven analogue to Fishacre’s color‑based reasoning.
There is no evidence that Sagan or contemporary astronomers directly drew on Fishacre’s medieval arguments. Still, the conceptual resonance is striking: long before spectroscopy and stellar nucleosynthesis, a medieval thinker used observation and logic to bridge the metaphysical divide between Earth and sky.
Originally featured on Nautilus.