1909 in science

artificial nitrogen fixation process which is the main industrial procedure for the production of ammonia nowadays

experiment conducted by R. A. Millikan and H. Fletcher to measure elementary electric charge

series of experiments (1908–1913) by Hans Geiger and Ernest Marsden, directed by Ernest Rutherford, at the University of Manchester, proving the existence of the atomic nucleus through alpha particle scattering on gold foil

overview of natural science-related events during the year of 1909

20th-century hybrid solar eclipse

20th-century partial solar eclipse