Chadwick Crater Honors British Physicist Sir James Chadwick

Summary: Chadwick Crater honors British physicist Sir James Chadwick, whose 1935 Nobel Prize in Physics recognized his discovery of the neutron in 1932.

Detail of Lunar Astronautical Chart (LAC) 28 shows Chadwick Crater as a far side crater, with nearest named neighbors De Roy Crater and Mendel Crater's satellite J to the southeast and northwest, respectively; courtesy NASA (National Aeronautics and Space Administration) / GSFC (Goddard Space Flight Center) / ASU (Arizona State University): U.S. Geological Survey, Public Domain, via USGS Astrogeology Science Center / Gazetteer of Planetary Nomenclature

Chadwick Crater honors British physicist Sir James Chadwick, who was awarded the Nobel Prize in Physics in 1935 for his 1932 discovery of the neutron.

Chadwick is a lunar impact crater in the lunar far side’s southeastern quadrant. The roughly circular crater exhibits a sharp-edged rim. Thickened south-southeastern inner walls account for an outward bulge in the crater’s outline. Chadwick’s interior floor appears uneven.

Chadwick is centered at minus 52.85 degrees south latitude, minus 101.34 degrees west longitude, according to the International Astronomical Union’s (IAU) Gazetteer of Planetary Nomenclature. The southern hemisphere crater obtains northernmost and southernmost latitudes at minus 52.36 degrees south and minus 53.34 degrees south, respectively. The high middle-latitude crater’s easternmost and westernmost longitudes occur at minus 100.54 degrees south and minus 102.15 degrees south, respectively. Chadwick’s diameter measures 29.74 kilometers.

De Roy Crater and Mendel J Crater occur as Chadwick’s nearest named neighbors. De Roy resides to the southeast of Chadwick. Mendel J lies to the northwest of Chadwick.

Slightly irregularly circular De Roy Crater occurs as the northernmost and easternmost member of the De Roy Crater system. Its location places it closer to Chadwick Crater than to its three satellites, which reside to the southwest of their parent.

De Roy Crater is centered at minus 55.24 degrees south latitude, minus 98.99 degrees west longitude. It marks northernmost and southernmost latitudes of minus 54.52 degrees south and minus 55.95 degrees south, respectively. De Roy finds easternmost and westernmost longitudes at minus 97.74 degrees west and minus 100.24 degrees west, respectively. De Roy Crater’s diameter measures 43.51 kilometers.

Mendel J numbers among the Mendel Crater system’s three satellites. Mendel J shares part of its parent’s southeastern rim.

Mendel J is centered at minus 51.51 degrees south latitude, minus 107.2 degrees west longitude. The satellite records northernmost and southernmost latitudes at minus 50.56 degrees south and minus 52.46 degrees south, respectively. It registers easternmost and westernmost longitudes at minus 105.68 degrees west and minus 108.73 degrees west, respectively. Mendel J’s diameter spans 57.59 kilometers.

Chadwick Crater honors British physicist Sir James Chadwick (Oct. 20, 1891-July 24, 1974). The International Astronomical Union (IAU) approved Chadwick as the crater’s official in 1985, during the organization’s XIXth (19th) General Assembly, held in New Delhi, India, from Monday, Nov. 18, to Saturday, Nov. 30.

Sir James was elected as a Fellow of The Royal Society (FRS) on Dec. 5, 1927, according to The Royal Society’s website. The Society’s election certificate noted, in particular, Chadwick’s investigations into the properties of alpha and beta particles and “on the magnitude of the charge on the nucleus and the law of force around it.” The certificate also cited Chadwick’s collaboration in pioneer research on alpha particle disintegration, since 1919, with nuclear physics pioneer Sir Ernest Rutherford, 1st Baron Rutherford of Nelson (Aug. 30, 1871-Oct. 19, 1937) at the University of Cambridge’s Cavendish Laboratory.

In 1932, Chadwick and his assistant, English physicist Norman Feather (Nov. 16, 1904-Aug. 14, 1978), who had been Chadwick and Rutherford’s doctoral student, discovered the neutron. Chadwick announced the discovery of the subatomic, non-electrically charged particle in a letter, dated Feb. 17, 1932, to Nature. The Swedish Academy of Sciences awarded the Nobel Prize in Physics in 1935 to Chadwick “for the discovery of the neutron.” The Nobel Laureate’s biography on the Nobel Prize website explains the significance of his discovery: “Chadwick in this way prepared the way towards the fission of uranium 235 and towards the creation of the atomic bomb.”

Chadwick was knighted for his achievements in physics in 1945.

The takeaways for Chadwick Crater, which honors British physicist Sir James Chadwick, are that the lunar impact crater occupies the far side’s southeastern quadrant; that the crater’s namesake is credited with the discovery of the neutron, a non-charged subatomic particle, in 1932; and that the Swedish Academy of Sciences awarded the Nobel Prize in Physics in 1935 to Chadwick for his significant discovery.

Detail of Shaded Relief and Color-Coded Topography Map shows Chadwick Crater as a high middle-latitude crater in the lunar far side’s southeastern quadrant: U.S. Geological Survey, Public Domain, via USGS Astrogeology Science Center / Gazetteer of Planetary Nomenclature

Acknowledgment

My special thanks to talented artists and photographers/concerned organizations who make their fine images available on the internet.

Image credits:

Detail of Lunar Astronautical Chart (LAC) 135 shows Chadwick Crater as a far side crater, with nearest named neighbors De Roy Crater and Mendel Crater's satellite J to the southeast and northwest, respectively; courtesy NASA (National Aeronautics and Space Administration) / GSFC (Goddard Space Flight Center) / ASU (Arizona State University): U.S. Geological Survey, Public Domain, via USGS Astrogeology Science Center / Gazetteer of Planetary Nomenclature @ https://planetarynames.wr.usgs.gov/images/Lunar/lac135_wac.pdf

Detail of Shaded Relief and Color-Coded Topography Map shows Chadwick Crater as a high middle-latitude crater in the lunar far side’s southeastern quadrant: U.S. Geological Survey, Public Domain, via USGS Astrogeology Science Center / Gazetteer of Planetary Nomenclature @ https://planetarynames.wr.usgs.gov/images/moon_nearside.pdf

For further information:

Andersson, Leif E.; and Ewen A. Whitaker. NASA Catalogue of Lunar Nomenclature. NASA Reference Publication 1097. Washington DC: NASA National Aeronautics and Space Administration Scientific and Technical Information Branch, October 1982.
Available via NASA NTRS (NASA Technical Reports Server) @ https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19830003761.pdf

Barnes, Melene. “Richard C. Carrington.” Journal of the British Astronomical Association, vol. 83, no. 2 (1973): 122-124.
Available via Harvard ADSABS @ http://adsabs.harvard.edu/full/1973JBAA...83..122B
Available via Harvard ADSABS @ http://adsabs.harvard.edu/pdf/1973JBAA...83..122B

Chadwick, James. “Existence of a Neutron.” Proceedings of the Royal Society A, vol. 136, issue 830 (June 1, 1932): 692-708.
Available via JSTOR @ https://www.jstor.org/stable/95816
Available @ https://royalsocietypublishing.org/doi/abs/10.1098/rspa.1932.0112

Chadwick, James. “Possible Existence of a Neutron.” Nature, vol. 129, no. 3252 (Feb. 27, 1932): 312.
Available via MIT @ http://web.mit.edu/22.54/resources/Chadwick.pdf
Available @ https://www.nature.com/articles/129312a0

Consolmagno, Guy; and Dan M. Davis. Turn Left at Orion. Fourth edition. Cambridge UK; New York NY: Cambridge University Press, 2011.

Grego, Peter. The Moon and How to Observe It. Astronomers’ Observing Guides. London UK: Springer-Verlag, 2005.

International Astronomical Union (IAU) / U.S. Geological Survey (USGS) Gazetteer of Planetary Nomenclature. “Chadwick.” USGS Astrogeology Science Center > Gazetteer of Planetary Nomenclature > Nomenclature > The Moon. Last updated Oct. 18, 2010.
Available @ https://planetarynames.wr.usgs.gov/Feature/1118

International Astronomical Union (IAU) / U.S. Geological Survey (USGS) Gazetteer of Planetary Nomenclature. “De Roy.” USGS Astrogeology Science Center > Gazetteer of Planetary Nomenclature > Nomenclature > The Moon. Last updated Oct. 18, 2010.
Available @ https://planetarynames.wr.usgs.gov/Feature/1444

International Astronomical Union (IAU) / U.S. Geological Survey (USGS) Gazetteer of Planetary Nomenclature. “Mendel J.” USGS Astrogeology Science Center > Gazetteer of Planetary Nomenclature > Nomenclature > The Moon. Last updated Oct. 18, 2010.
Available @ https://planetarynames.wr.usgs.gov/Feature/11324

Levy, David H. Skywatching. Revised and updated. San Francisco CA: Fog City Press, 1994.

Marriner, Derdriu. “Bragg Crater Honors British Physicist Sir William Henry Bragg.” Earth and Space News. Wednesday, March 14, 2012.
Available @ https://earth-and-space-news.blogspot.com/2012/03/bragg-crater-honors-british-physicist.html

Marriner, Derdriu. “Pogson Crater Honors British Astronomer Norman Robert Pogson.” Earth and Space News. Wednesday, June 20, 2012.
Available @ https://earth-and-space-news.blogspot.com/2012/06/pogson-crater-honors-british-astronomer.html

Massey, Harrie; and N. Feather. “James Chadwick 20 October 1891-24 July 1974 Elected F.R.S. 1927.” Biographical Memoirs of Fellows of the Royal Society, vol. 22 (November 1976): 10-70.
Available via JSTOR @ https://www.jstor.org/stable/769732

The Moon Wiki. “Chadwick.” The Moon > Lunar Features Alphabetically > C Nomenclature.
Available @ https://the-moon.us/wiki/Chadwick

The Moon Wiki. “De Roy.” The Moon > Lunar Features Alphabetically > D Nomenclature.
Available @ https://the-moon.us/wiki/De_Roy

The Moon Wiki. “IAU Directions.” The Moon.
Available @ https://the-moon.us/wiki/IAU_directions

The Moon Wiki. “Mendel.” The Moon > Lunar Features Alphabetically > M Nomenclature.
Available @ https://the-moon.us/wiki/Mendel

Moore, Patrick, Sir. Philip’s Atlas of the Universe. Revised edition. London UK: Philip’s, 2005.

The Nobel Prize. “James Chadwick: Biographical.” The Nobel Prize > Prizes > Physics > 1935.
Available @ https://www.nobelprize.org/prizes/physics/1935/chadwick/biographical/

The Royal Society. “Chadwick; James (c 1660-1697).” The Royal Society > Collections > Fellows.
Available @ https://collections.royalsociety.org/DServe.exe?dsqIni=Dserve.ini&dsqApp=Archive&dsqCmd=Show.tcl&dsqDb=Persons&dsqPos=3&dsqSearch=%28%28text%29%3D%27Chadwick%27%29

Swings, J.P. (Jean-Pierre), ed. XIXth General Assembly Transactions of the IAU Vol. XIX B Proceedings of the 19th General Assembly New Delhi, India, November 18-30, 1985. Washington DC: Association of Universities for Research in Astronomy, Jan. 1, 1986.
Available via IAU @ https://www.iau.org/publications/iau/transactions_b/