Yearly Archives: 2017

Cat's Eye Nebula — December 21 is Ira Sprague Bowen’s birthday. Bowen was an American astrophysicist and spectroscopist who disproved the existence of the element ‘nebulium‘. In 1860, one of the new tools for scientists was absorption spectrum analysis. Look closely at the light after it passes through a heated gas with a diffraction […]

Today in Science History – December 21 – The Element ...

This entry was posted on December 11, 2017 by Todd Helmenstine (updated on October 23, 2024)

Van de Graaff Generator — December 20 is Robert Van de Graaff’s birthday. Van de Graaff was an American physicist who invented the Van de Graaff electrostatic generator. Small Van de Graaff generators are common sights at science demonstrations to illustrate the effects of electrical charges. The most common sight is someone with long, fine […]

Today in Science History – December 20 – Van de ...

This entry was posted on December 10, 2017 by Todd Helmenstine (updated on May 16, 2021)

Robert Andrews Millikan — December 19 marks the passing of Robert Millikan. Millikan was an American physicist best known for his famous oil drop experiment. The purpose of this experiment was to measure the charge of an electron. Millikan and Harvey Fletcher sprayed charged drops of oil between two horizontal charged plates. Gravity pulls […]

Today in Science History – December 19 – Robert Millikan ...

This entry was posted on December 10, 2017 by Todd Helmenstine (updated on August 19, 2025)

J.J. Thomson (1856 - 1940) — December 18 is J. J. Thomson’s birthday. Thomson was a British physicist who is best known for the discovery of the electron. He was investigating the discharge of gases in a cathode ray tube. He theorized cathode rays were made up of ‘corpuscles’ or particles smaller than atoms. He also […]

Today in Science History – December 18 – J. J. ...

This entry was posted on December 10, 2017 by Todd Helmenstine (updated on April 21, 2026)

Willard Libby — December 17 is Willard Libby’s birthday. Libby was the American physical chemist who developed the carbon-14 dating technique. This method is used to determine the age of ‘once living’ objects up to approximately 50,000 years. Carbon 14 is an isotope of carbon created naturally in the atmosphere by cosmic rays. […]

Today in Science History – December 17 – Carbon 14 ...

This entry was posted on December 9, 2017 by Todd Helmenstine (updated on January 29, 2025)

Johann Wilhelm Ritter — December 16 is Johann Wilhelm Ritter’s birthday. Ritter was a German scientist who invented one of the first dry pile galvanic batteries. Early batteries used electrodes dipped in an acid solution where the energy is produced through oxidation reactions. A dry pile uses just enough moisture to function without the […]

Today in Science History – December 16 – Johann Ritter

This entry was posted on December 9, 2017 by Todd Helmenstine (updated on December 16, 2021)

Wolfgang Pauli — December 15 marks the passing of Nobel Prize-winning Austrian physicist Wolfgang Pauli. Pauli is best known for the Pauli Exclusion Principle which states no two identical particles with half-integer spin cannot occupy the same quantum state in a quantum system simultaneously. This is typically applied to electrons around an atom. […]

Today in Science History – December 15 – Pauli Effect Recently updated !

This entry was posted on December 8, 2017 by Todd Helmenstine (updated on August 15, 2026)

Edward Tatum — December 14 is Edward Tatum’s birthday. Tatum was an American biochemist who discovered with another American geneticist, George Beadle, that chemical processes in organisms are controlled by the organism’s genes. These processes can be separated into distinct sequential reactions where each reaction would be controlled by one gene. They also […]

Today in Science History – December 14 – Edward Tatum ...

This entry was posted on December 8, 2017 by Todd Helmenstine (updated on May 13, 2025)

Aurora Borealis — December 13 is the birthday of Norway’s Kristian Birkeland. Birkeland was a physicist who made several discoveries centered around electricity. He was the first to demonstrate how charged particles could cause air to emit light around a magnetized sphere to explain the Aurora Borealis and Aurora Australis. The green and […]

Today In Science History – December 13 – Kristian Olaf ...

This entry was posted on December 8, 2017 by Todd Helmenstine (updated on July 25, 2023)