Physicist Ernest Rutherford was born in Brightwater, New Zealand #OTD in 1871.
He discovered the nucleus, proton, and α and β particles; explained nuclear decay; and was the first person to successfully transmute one element into another.
He dropped out of the *eighth grade* and had little formal education, but a knack for difficult observations helped him collect much of the data used to establish what we now call Hubble’s Law.
Astronomer Helen Sawyer Hogg was born #OTD in 1905. She was an authority on variable stars and globular clusters, and a pioneer of communicating science to the public.
Image: University of Toronto, Department of Astronomy and Astrophysics
Aerodynamics engineer and mathematician Irmgard Flügge-Lotz was born #OTD in 1903.
She advanced the understanding of aerodynamic pressure on wings and turbine blades, pioneered the theory of discontinuous control systems, and was the first woman named full professor of engineering at Stanford.
Medical physicist and radiologist Edith Quimby was born #OTD in 1891.
One of the founders of nuclear medicine, she developed diagnostic applications for X-rays and radioisotopes. Her research on the penetrating power of radiation established safe levels for its use in treatments.
#OTD in 1609, Galileo Galilei aimed his telescope at the Moon.
While not being the first person to observe the Moon through a telescope (English mathematician Thomas Harriot had done it four months before but only saw a "strange spottednesse"), Galileo was the first to deduce the cause of the uneven waning as light occlusion from lunar mountains and craters. In his study, he also made topographical charts, estimating the heights of the mountains. via @wikipedia
Friends, here is a fun little physics story about satellites and relativity. It’s a day late for an #OTD, but please indulge me.
The Navigation Technology Satellite 2 (NTS-2) was launched into orbit on June 23, 1977, an early step in establishing the GPS NAVSTAR network. It was the first satellite to carry a Cesium atomic clock into orbit! 🧵
Can we productively talk about how many alien civilizations throughout the Milky Way might be actively broadcasting or receiving messages? How would we estimate that?
N ≈ R×fp×ne×fl×fi×fc×L
R = ⭐️ formation rate fp = fraction of ⭐️ with 🌎 ne = 🌎 per ⭐️ on avg that could support life fl = fraction with life fi = fraction of life becoming intelligent fc = fraction that 📡 into 🌌 L = how long they broadcast
Speaking of, the Hubble Space Telescope sent its first image back to Earth #OTD in 1990.
Folks knew right away that something was wrong with the optics, but the problem was eventually corrected.
Ground Image: E. Persson (Las Campanas Observatory, Chile)/Observatories of the Carnegie Institution of Washington Hubble Image: NASA, ESA, and STScI https://mastodon.social/@mcnees/110378772317401238
An #OTD thread from last year, about the scientific contributions of Julius Oppenheimer.
A lot of "common knowledge" about black holes – infinite redshift, the slow progress of an infalling observer from the point of view of a distant spectator – can be traced back to an influential paper Oppenheimer wrote in 1939. https://mastodon.social/@mcnees/110245056828062741
#OnThisDay, 20 Apr 1902, Marie and Pierre Curie refine radium chlorine. The discovery leads to Marie being the first woman to win the Nobel Prize for Physics in 1903.
The Academy originally planned to award only Pierre and Henri Becquerel. Pierre insisted that Marie should also be included.