On this day, Aug. 12 ...

1939: The MGM movie musical "The Wizard of Oz," starring Judy Garland, has its world premiere at the Strand Theater in Oconomowoc, Wis., three days before opening in Hollywood.

Also on this day:

1909: The Indianapolis Motor Speedway, home to the Indianapolis 500, first opens.

The Indianapolis Motor Speedway, home to the Indianapolis 500, first opens. 1937: President Franklin D. Roosevelt nominates Hugo Black to the U.S. Supreme Court.

President Franklin D. Roosevelt nominates Hugo Black to the U.S. Supreme Court. 1944: During World War II, Joseph P. Kennedy Jr., eldest son of Joseph and Rose Fitzgerald Kennedy, is killed with his co-pilot when their explosives-laden Navy plane blows up over England.

During World War II, Joseph P. Kennedy Jr., eldest son of Joseph and Rose Fitzgerald Kennedy, is killed with his co-pilot when their explosives-laden Navy plane blows up over England. 1953: The Soviet Union conducts a secret test of its first hydrogen bomb.

1981: IBM introduces its first personal computer, the model 5150, at a press conference in New York.

1985: The world's worst single-aircraft disaster occurs as a crippled Japan Airlines Boeing 747 on a domestic flight crashes into a mountain, killing 520 people. (Four people survive.)

2004: New Jersey Gov. James E. McGreevey announces his resignation and acknowledges that he'd had an extramarital affair with another man.