On this day in 1882 – October 5th – Robert Goddard was born.
He was an American engineer, professor, physicist, and inventor who is credited with creating and building the world's first liquid-fueled rocket. Although he received little public support in his lifetime, he's now considered one of the founding fathers of modern rocketry.
On this day in 1873 – October 8th – Danish chemist and astronomer Ejnar Hertzsprung was born in Copenhagen.
Hertzsprung and American astronomer Henry Norris Russell, independently developed a scatter plot of stars that related their absolute magnitudes to their effective temperatures. It's nown as the Hertzsprung–Russell diagram (abbreviated H-R diagram).