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February 21 - Births – Physicists born on February 21

No physicist were born on this day

February 21- Deaths – Physicists died on February 21

George Ellery Hale (29 Jun 1868 - 21 Feb 1938)

He was an American astronomer known for his development of important astronomical instruments. He founded Mt. Wilson Observatory in December 1904. He encouraged research in galactic and extragalactic astronomy as well as solar and stellar astrophysics. He also discovered that sunspots were regions of relatively low temperatures and high magnetic fields. The Hale telescope (1948) was named after him because he tirelessly raised funds for the 200-inch reflecting telescope at Palomar Mountain Observatory.

George Francis Fitzgerald (3 Aug 1851 - 21 Feb 1901)

He was an Irish physicist who helped in laying a foundation for wireless telegraphy. He first developed a theory called the Lorentz-FitzGerald that said a material object moving through an electromagnetic field would exhibit a contraction of its length in the direction of motion. He also studied electrolysis as well as electromagnetic radiation.

Heike Kamerlingh Onnes (3 Aug 1851 - 21 Feb 1901)

He was a Dutch physicist who was awarded the 1913 Noble prize for physics for his contribution in the field of low-temperature physics in which he liquified hydrogen and helium. He obtained his first sample of liquid helium in 1908. His accomplishment was published in The Times on 20 July 1908 after a few more days of verification. He also discovered superconductivity.

Inge Lehmann (13 May 1888 - 21 Feb 1993)

She was the first true female geophysicist in the world and the first person in that field in her home country. She identified the Lehmann Discontinuity in the seismic structure of the earth which marks a previously unknown boundary at the solid inner core of the Earth in 1936. She published this in the paper called “P” (for Prime). The paper was based on her interpretation of worldwide shockwave records from a large earthquake near New Zealand in 1929. She received awards from around the world.

February 21 - Events – Physics Events on February 21

Chlorine Gas

Humphry Davy read a paper in 1811 to the Royal Society and introduced the name “chlorine” from the Greek word for “green”, for the bright yellow-green gas chemists then known as oxymuriatic gas. Davy reported on his numerous experiments with oxymuriatic gas, which appeared to have many of the reactive properties of oxygen. When chlorine was first obtained from a reaction in which HCl, the yellow-green gas had been thought to be a compound containing oxygen. Later, Davy’s careful work showed that the chlorine gas was in fact an element.

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