July 28: Townes, Piccard, and Petrie born; first solar eclipse photo; Hahn and Crick die

Charles H. Townes

American physicist Charles Hard Townes was born this day in 1915.

 

Townes worked on the theory and application of masers and lasers, and shared the 1964 Nobel Prize in Physics with Nikolay Basov and Alexander Prokhorov. Townes directed the US government’s Science and Technology Advisory Committee for the Apollo lunar landing program, and after becoming a professor of the University of California he began an astrophysics program that produced several important discoveries, including the existence of the black hole at the centre of the Milky Way galaxy.

Jacques Piccard

Swiss oceanographer Jacques Piccard was born today in 1922. With his father Auguste, Piccard designed bathyscaphes for deep-sea exploration, including the Trieste, in which he dived with U.S. Navy Lt. Don Walsh in 1960 to the bottom of the Mariana Trench, the deepest known location on the surface of Earth’s crust.

Flinders Petrie

We remember British archaeologist  Sir William Matthew Flinders Petrie, who died this day in 1942, aged 89.  Petrie made valuable contributions to the techniques and methods of field excavation, and invented a sequence dating method that enabled reconstruction of history from the remains of ancient cultures.

Berkowski photographs solar eclipse

On this day in 1851, a total solar eclipse was first captured on a Daguerreotype photograph by Berkowski (first name unknown), at the Royal Observatory in Königsberg, Prussia (now Kalinigrad in Russia).

Otto Hahn

We commemorate the death of German chemist and physicist Otto Hahn who died on this day in 1968, aged 89. Hahn was a pioneer in the fields of radioactivity and radiochemistry. With Lise Meitner Hahn discovered radioactive isotopes of radium, thorium, protactinium and uranium; and in 1938, Hahn, Meitner, and Fritz Strassmann discovered nuclear fission, for which Hahn received the 1944 Nobel Prize in Chemistry.

Francis Crick

English molecular biologist Francis Crick died on this day in 2004, aged 88.  With James Watson and Rosalind Franklin, Crick played a crucial roles in deciphering the helical structure of the DNA molecule. Crick and Watson’s paper in Nature in 1953 laid the groundwork for understanding DNA structure and functions. Together with Maurice Wilkins, Crick and Watson (but not Franklin) were jointly awarded the 1962 Nobel Prize in Physiology or Medicine.