- Jan 5 Mao Zedong writes "A Single Spark Can Start a Prairie Fire"
- Mar 12 Mohandas Gandhi begins 200m (300km) march protesting British salt tax
- Mar 13 Clyde Tombaugh announces discovery of Pluto at Lowell Observatory
- Apr 2 Ras Tafari Makonnen becomes Emperor Haile Selassie of Abyssinia (Ethiopia)
- Jun 24 1st radar detection of planes, Anacostia, Washington, D.C.
- Jul 13 1st-ever football (soccer) World Cup competition begins in Uruguay
- Jul 30 Uruguay beats Argentina 4-2 for association football's 1st FIFA World Cup in Montevideo
- Nov 2 Coronation of Ras Tafari Makonnen as Haile Selassie I, 225th Emperor of Ethopian Solmonic Dynasty
"Mickey Mouse" comic strip 1st appears
On January 13, 1930
Marguerite Perey discovers francium (Fr), the last naturally occurring element to be found
On January 7, 1930