The Astronomer by Johannes Vermeer

An astronomer is a scientist in the field of astronomy who studies stars, planets, moons, comets and galaxies, as well as many other celestial objects - either in Observational astronomy, in analyzing the data or in theoretical astronomy. A related but distinct subject, cosmology, is concerned with studying the Universe as a whole. An astronomer researches the world beyond Earth.

Johannes Hevelius was famed for his work on sunspots, and being the first to study the surface of the moon.

The Magnificent Observatory and Discoveries of Johannes Hevelius   Ancient Origins - February 3, 2016
Johannes Hevelius is one of the symbols of Gdansk, Poland. He is also one of the three great intellectuals, along with Fahrenheit and Schopenhauer, who were born in this city. During HeveliusŐ life, his observatory was known as one of the most important centers for astronomy in Europe.