1930.........1940

1930

• Clyde W. Tombaugh (1906-1997) was a young amateur astronomer working at the Lowell Observatory in Flagstaff, Arizona, in 1930 when he discovered a planet, right where astronomer Percival Lowell had said it would be in 1915. Pluto is not always the farthest planet from the sun. Its orbit brings the small, cold planet closer than Neptune for about 20 years at a time every 248 years. On March 15, 1999, Pluto crossed Neptune’s path and will again be the farthest planet from the sun until the mid-23rd century.

1931

• The last of the great art deco skyscrapers, the Empire State Building in midtown Manhattan was completed in 1931 - for half the estimated construction cost, thanks to the Depression. For its ceremonial opening, President Herbert Hoover turned on the lights by pressing a button in Washington, DC. At 1,250 feet (not including antennae added in 1950), the building was the tallest in the world until 1973. Over the years, the landmark has received countless tourists, including Hollywood's King Kong.
•  
  The first woman to fly solo across the Atlantic Ocean, Amelia Earhart helped to promote aviation and change attitudes about what modern women could accomplish.

1932

• Great Depression. By 1932, some 17 million workers - one-third of the labor force - were unemployed. Families slept in doorways and fields; self-respecting middle-class people overcame their pride to ask for handouts. Even those fortunate enough to keep a roof over their heads were marked for life by memories of financial anxiety.

• Japanese Bomb Shanghai
  The West stands idly by as Japanese bombers flatten Shanghai in their expansion into Asia.
  

1933

• A shrewd and murderous autocrat, Joseph Stalin (1879-1953) succeeded Lenin as leader of the Soviet Union in 1924. He ruthlessly enforced collectivization and industrialization. In ongoing bloody purges, he staged mock trials and executed thousands of intelligentsia and other scapegoats. His Red Army was victorious against Hitler's troops in World War II, but at a devastating price, and at conferences with the Allied leaders, Stalin cunningly set the stage for Soviet expansion and the cold war.

• Hitler Seizes Power
  Adolf Hitler, swept into power on a tidal wave of German misery and anger, becomes chancellor of
  Germany and almost immediately gives himself dictatorial powers.

1934

• Mao Saves Communism
  Guerrilla fighter Mao Tse-tung leads Chinese
  communists on a 6,000-mile Long March and rescues the movement from eradication.
  

1935

• Hitler Curtails Jews’ Rights
  Hitler introduces the Nuremberg Laws to rescind the rights of German Jews.

• Italians Demolish Ethiopia
  Italy’s Fascist dictator Benito
  Mussolini invades and conquers
  Ethiopia. The League of Nations
  does nothing to stop the Italian forces
  

1936

• Determined to proclaim Germany's resurgence to the world, Adolf Hitler spent $30 million preparing Berlin for the 1936 Olympics. He had the city festooned with Nazi symbols, and proudly published the party's ideology. The site was controversial, but the games had been awarded to Berlin two years before the Nazis came to power in 1933, and talk of a boycott did not go far. Forty-nine nations, including the United States, decided to participate at Berlin.
• 
  First named Hoover Dam, then Boulder Dam, then Hoover Dam again, the massive structure on the border of Nevada and Arizona was built in the Depression years of 1931 through 1936. The hydroelectricity the dam generates supplies both of its border states and southern California. Since its construction, the dam has drawn tourists who marvel at its engineering and impressive scale: 726 feet high and 1,244 feet long.

• Civil War Wracks Spain
  Fascist Francisco Franco,with the help of German
  weapons, begins a civil war to wrest power from the republic.

• King Trades Crown for Love
  Edward VIII of Great Britain abdicates and marries American divorcee Wallis Simpson. Rumors swirl that both are feeding information to the Nazis.

• Owens Shatters Aryan Dreams
  U.S. track superstar Jesse Owens, an African-American, captures four gold medals at the 1936 Summer Olympics in Berlin in front of Adolf Hitler. Germany goes on, however, to win most medals in the Olympics.

1937

• For a brief decade or so, airships seemed a viable means of commercial transportation. In 1936, the German luxury airship Hindenburg, a rigid 804-foot dirigible that traveled up to 84 miles per hour, carried more than 1,000 passengers from Germany to the United States in 10 trips. But in a spectacular accident on May 6, 1937, the Hindenburg burst into flames over Lakehurst, New Jersey. Thirty-six people were killed, and the experiment with airship travel ended.

• Germans Target Civilians
  German bombers attack Guernica—a Spanish a town of no military worth— killing hundreds of civilians. Picasso will later reflect on the horror of the action in one of his paintings.
  

1938

• On April 6, 1938, chemist Roy Plunkett (1910-1994), working for the DuPont chemical company, discovered polytetrafluoroethylene, later dubbed Teflon, while attempting to make an improved refrigerant. The slippery, inert substance proved to be impermeable to heat, cold, and acid. More slippery than ice, Teflon has been used in fishing tackle, cooking pans, artificial arteries, and even roofs and Apollo moon suits.

• Germans Attack Jews
  In a late-night rampage, Nazis destroy German Jewish property and attack Jews.
  The attack is called Kristallnacht, after the
  shattered glass on the streets.

• Look, Up in the Sky!
  Superman debuts as a comic
  book character.

1939

• The earliest televisions appeared in American homes in the late 1930s, and the first person to appear in a broadcast was President Franklin Roosevelt, speaking from the New York World's Fair in 1939. Commercial broadcasting began in 1941 but stalled until after the war. Although there were scarcely any programs to watch, and televisions cost $500 (when families earned less than $3,000 annually), 7 million sets were sold by 1950. The country was poised for the television age.
• 
  About 14 years earlier, the desire for a synthetic fiber led DuPont scientist Wallace Hume Carothers (1896-1937) to synthesize nylon, a polyamide that could be produced as fibers, filaments, sheets, or bristles. The new material was wildly successful when introduced in 1939. Besides its widespread use in hosiery, nylon became a World War II essential for parachutes, rope, machine parts, and sutures.

• WWII Begins
  Germany invades Poland on Sept. 1.
  France and Great Britain finally declare war on Germany.

• Scientist Splits Atom
  Using a cyclotron, John Dunning splits an atom in his lab at Columbia University, suggesting that nuclear fission is possible.

• The shockingly swift conquest of Poland was Adolf Hitler's first awful demonstration of modern blitzkrieg warfare. European armies of the day were not prepared for the combined force of encircling tanks, planes, infantry, artillery, and cavalry. The German and Polish forces were matched in number when Hitler invaded on September 1, 1939, but the Germans had superior technology and technique. By September 20, virtually the entire country had surrendered to the German or Soviet armies.