Learn about the history of science by reading about the significant scientific events that took place on this day in history.
1967 - J. Robert Oppenheimer died.
Oppenheimer was the American physicist who was the lead researcher for the Manhattan Project and is considered the 'father of the atomic bomb'.
1957 - Joseph Gilbert Hamilton died.Hamilton was a medical physicist who pioneered the use of radioisotopes for treating and diagnosing diseases. He injected a radioactive sodium solution into a leukemia patient to treat the disease and showed radioactive iodine was useful to treat thyroid disease. He died of leukemia believed to be a result of his work.
1957 - Henry Norris Russell died.Russell was an American astrophysicist who is best known for the Hertzsprung-Russell diagram which shows the relationship between star brightness and spectral type. He developed a method to compute the distance to binary star systems and used the light from eclipsing binary stars to calculate their mass. He also described the coupling of electron angular momentum and spin quantum numbers known as Russell-Saunders coupling.
1930 - Clyde Tombaugh discovers Pluto.
American astronomer Clyde Tombaugh discovered a planet outside the orbit of Neptune. He would load the images in a device called a blink comparator that rapidly switches the two photographs. This allowed Tombaugh to detect slight differences between the photographs which would suggest movement. He found a change from his late January plates and confirmed the discovery with another photograph.
1871 - Harry Brearley was born.Brearley was an English metallurgist who invented stainless steel. He was investigating the corrosion of gun barrels and trying to find a steel that would better resist the high temperatures and pressures from firing. He found adding chromium and nickel to carbon steel put a layer of rust resistance on the steel. He marketed his discovery in his hometown of Sheffield, England by producing "rustless" knives, pots and other food related uses.
1838 - Ernst Mach was born.
Mach was an Austrian physicist who primarily researched how people perceive their surrounding through studies in acoustics and optics. His work with optical interference, shock waves and the Doppler effect led to theories where measured phenomenon depended on the frame of reference of the observer and their relationship to the phenomenon. This would lead to much of Einstein's theory of relativity. He is also known for the unit of speed known as the Mach number, the ratio of the speed of an object to the speed of sound.
1799 - Johann Hedwig died.
Hedwig was a German botanist who pioneered bryology, or the study of mosses. His work was compiled and published after his death in Species Muscorum Frondosorum. It was a comprehensive study of nearly all known mosses known at the time.
1745 - Alessandro Volta was born.
Volta was an Italian physicist who was a pioneering figure in early electricity research and invented the chemical electric battery. He introduced the concept of electromotive force, or the force required to separate positive and negative charges. His battery was similar to the citrus battery using zinc and copper electrodes separated by an acid.
1677 - Jacques Cassini was born.
Cassini II was a French astronomer who was the son of the Italian astronomer Giovanni Cassini. He compiled the first tables of the orbits of Jupiter and Saturn's moons and succeeded his father as director of the Paris Observatory. He also proposed the theory that the Earth was shaped like an ellipsoid rather than just flattened at the poles.