John A. O'Keefe (astronomer)

'''John Aloysius O'Keefe III''' (October 13, 1916 – September 8, 2000) was an expert in planetary science and astrogeology with the National Aeronautics and Space Administration (NASA) from 1958 to 1995.

He and his co-authors, Ann Eckels and Ken Squires, are credited with the discovery that the Earth had a significant third degree zonal spherical harmonic in its gravitational field using U.S. Vanguard 1 satellite data collected in the late 1950s. The Earth's pear shape as it was known became front-page news and was even the subject of a "Peanuts" cartoon. For that, he is credited as the "father of space geodesy".

He was the first to propose the idea of a scanning microscope in 1956 and he is the co-discoverer of the YORP effect (short for Yarkovsky-O’Keefe-Radzievskii-Paddock effect), an effect resulting from sunlight which causes a small celestial body such as an asteroid or meteor to spin up or down. Provided by Wikipedia