January 8, 1587 – March 19, 1616
Johannes Fabricius, eldest son of David Fabricius (1564-1617), was a German astronomer and a discoverer of sunspots, independently of Galileo Galilei.
Johannes was born in Resterhafe (Friesland). He returned from university in the Netherlands with telescopes that he and his father turned on the Sun. Despite the difficulties of observing the sun directly, they noted the existence of sunspots, the first confirmed instance of their observation (though unclear statements in East Asian annals suggest that Chinese astronomers may have discovered them with the naked eye previously, and Fabricius may have noticed them himself without a telescope a few years before). The pair soon invented camera obscura telescopy so as to save their eyes and get a better view of the solar disk, and observed that the spots moved. They would appear on the eastern edge of the disk, steadily move to the western edge, disappear, then reappear at the east again after the passage of the same amount of time that it had taken for it to cross the disk in the first place.
Copies of a map he made of Frisia in 1589 are also still extant. He is also named in Jules Verne's From the Earth to the Moon as someone who claimed to have seen lunar inhabitants through his telescope, though that particular fact is merely part of Verne's fiction.
The Lunar crater Fabricius is named after his father, David Fabricius.