André-Louis Danjon
André-Louis Danjon (French: [ɑ̃dʁelwi dɑ̃ʒɔ̃]; 6 April 1890 – 21 April 1967) was a French astronomer who served as director of the Observatory of Strasbourg from 1930 to 1945 and of the Paris Observatory from 1945 to 1963. He developed several astronomical instruments to examine the regularity of the rotation of the earth and among his discoveries was an acceleration of the rotation of the Earth during periods of intense solar activity occurring in 11-year cycles correlated with an increase in earthquakes.