a German astronomer remembered for his work on sunspots. Schwabe was trying to discover a new planet inside the orbit of Mercury which was tentatively called Vulcan. Because of the proximity to the Sun, it would have been very difficult to observe Vulcan, and Schwabe believed one possibility to detect the planet might be to see it as a dark spot when passing in front of the Sun. For 17 years, from 1826 to 1843, on every clear day, Schwabe would scan the sun and record its spots trying to detect Vulcan among them.
