Mary Doan (born 1907)

In 1907, in the year that Mary Doan was born, radiometric dating, a recently discovered technology that could date rocks, found that the earth was 2.2 billion years old which was dramatically older than previously thought. Later refinements and advancements in science would date the age of the earth at over 4.5 billion years.

In 1923, on August 2, President Warren G. Harding died in office, apparently of a heart attack. He was staying at the Palace Hotel in San Francisco after completing a nationwide tour. Suffering from cramps, indigestion, a fever and shortness of breath, his doctor thought he had food poisoning. After several days of being ill, he suddenly shuddered, slumped over, and died. There were rumors of foul play (some thought that his wife had poisoned him because of his affairs) but no evidence has ever been found.

In 1953, on July 27th, the Korean Armistice Agreement was signed. The Armistice was to last until "a final peaceful settlement is achieved". No peaceful settlement has ever been agreed upon.

In 1971, in March, Congress passed the Twenty-sixth Amendment to the United States Constitution, which lowered the voting age to 18 (from 21). It was a response to the criticism that men could fight at 18, but not vote for the policies and politicians who sent them to war. The states quickly ratified the Amendment and it was signed into law on July 1st by President Richard Nixon.

In 1986, on January 28th, the space shuttle Challenger exploded 73 seconds after launch. All seven crew members died. The cause of the explosion was later found to be a failed O-ring. The O-ring failure was due to the unusually cold conditions at Cape Canaveral.