Since its founding in 1891, many people have passed through the doors of the Vatican Observatory.  A quick perusal of our guestbook reveals several Names, including Popes, nobel laureates, astronauts, actors, and saints. Today’s guestbook entry is from June 5, 1909, when George E. Hale made a visit. Next to his name, George Ellery Hale (1868-1938) wrote “Mt. Wilson Solar Observatory, California.” The year prior to his visit, he used the Zeeman effect–(see the previous post on H. A. Lorentz)–to discover magnetic fields in sunspots. He also found that, between sunspot cycles, the magnetic polarity of fields through sunspots in northern vs southern hemisphere switches orientation – what is today known as Hale’s Law (or the Hale-Nicholson Law). In 1913, Hale advised Albert Einstein of the possibility of observing the effects of general relativity on starlight passing near the Sun, which he suggested might be possible during a total solar eclipse.  This led to the eclipse observing expeditions of Arthur … Continue reading →