Astronomer or alchemist?

I expect you’ve heard of the Kepler Space Telescope launched by NASA  in 2009 to discover Earth-size planets orbiting other stars.   It is retired now,  but it was named after astronomer and mathematician Johannes Kepler,  who was an important figure in the 17th-century scientific revolution.

A chemical  analysis of pages  from Kepler’s manuscript about the moon has found high levels of metals like gold,  silver,  mercury and lead.   He wasn’t known to study alchemy,  but it was still practised in the 16th and 17th centuries,  and a close friend of his did study the ancient  branch of natural philosophy.   Truth be told,  most scientists of the era at least dabbled in that area.