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 August 6, 1913, when Sergei Blazhko made a visit.
Next to his name, Sergei Nikolaevich Blazhko (1870-1956) wrote, "Observ. astron. de l'univ. de Moscou" ("Astronomical observer of the University of Moscow." [n.b. The discrepancy in spelling of his name is due to transliteration from the Russian: сергей блажко.]
He studied RR Lyrae variable stars. In his research, he discovered that they have a secondary variation in amplitude and period. This is now known as the Blazhko effect.
He also studied binary stars, developing methods for computing their orbits.
There is a crater on the moon named for him.