Bragg Crater Honors British Physicist Sir William Henry Bragg

Summary: The lunar far side’s Bragg Crater honors British physicist Sir William Henry Bragg, uniquely awarded the 1915 Nobel Physics Prize with his younger son.

Detail of Lunar Astronautical Charts (LAC) 36 shows the lunar far side’s Bragg Crater system of parental Bragg (center), Bragg H (center right), Bragg M (lower right) and Bragg P (lower center); 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

The lunar far side’s Bragg Crater honors British physicist Sir William Henry Bragg, whose sharing of the 1915 Noble Prize in Physics with his younger son, William, uniquely represents the first and only father-son Nobel laureates.

Bragg Crater occupies the lunar far side’s northeastern quadrant. The ancient lunar impact crater lies just beyond the near side’s northwestern limb.

Bragg Crater’s western rim is more intact than its eastern rim. Craterlets riddle Bragg’s northern and eastern rim. A craterlet almost approximates the interior floor’s midpoint.

Bragg Crater is centered at 42.33 degrees north latitude, minus 103.44 degrees west longitude, according to the International Astronomical Union’s (IAU) Gazetteer of Planetary Nomenclature. The primary crater’s northernmost and southernmost latitudes reach 43.6 degrees north and 41.05 degrees north, respectively. Its easternmost and westernmost longitudes extend to minus 101.72 degrees west and minus 105.16 degrees west, respectively. Bragg Crater’s diameter measures 77.21 kilometers.

Bragg Crater parents three satellites in its environs. Bragg H snuggles on its parent’s east-southeastern rim. Satellites M and P lie, respectively, to the south and southwest of their parent.

Satellite H claims the closest position to its parent. Its position on parental Bragg’s east-southeastern rim also qualifies it as the most northerly and the most easterly of the Bragg Crater system’s three satellites.

Bragg H is centered at 41.47 degrees north latitude, minus 101.35 degrees west longitude. The satellite posts northernmost and southernmost latitudes of 42.07 degrees north and 40.86 degrees north, respectively. H marks easternmost and westernmost longitudes at minus 100.54 degrees west and minus 102.16 degrees west, respectively.

Bragg H’s diameter of 36.61 kilometers qualifies it as the second largest of the Bragg Crater system’s three satellites. The satellite’s diameter edges, at almost 47.5 percent, toward half of its parent’s diameter of 77.21 kilometers.

Satellite M’s location to the south-southeast of its parent qualifies it as the most distant of the Bragg Crater system’s three satellites. M also claims the Bragg Crater system’s most southerly position.

Bragg M is centered at 38.87 degrees north latitude, minus 102.77 degrees west longitude. The satellite obtains northernmost and southernmost latitudes of 39.6 degrees north and 38.14 degrees north, respectively. Its easternmost and westernmost longitudes occur at minus 101.83 degrees west and minus 103.7 degrees west, respectively.

Bragg M’s diameter of 44.32 kilometers qualifies it as the largest of the Bragg Crater system’s three satellites. M’s diameter equates to almost 57.5 percent of its parent’s 77.21-kilometer diameter.

Satellite P lies to the northwest of Bragg M. P’s location qualifies it as the most westerly of the Bragg Crater system’s three satellites.

Bragg P is centered at 39.75 degrees north latitude, minus 104.76 degrees west longitude. The satellite registers northernmost and southernmost latitudes at 40.23 degrees north and 39.27 degrees north, respectively. It records easternmost and westernmost longitudes of minus 104.14 degrees west and minus 105.38 degrees west, respectively.

Bragg P’s diameter of 28.95 kilometers qualifies it as the smallest of the Bragg Crater system’s three satellites. P’s diameter equates to 37.5 percent of its parent’s 77.21-kilometer diameter.

Bragg Crater honors British physicist Sir William Henry Bragg (July 2, 1862-March 12, 1942). The International Astronomical Union (IAU) approved Bragg as the crater’s official name in 1970, during the organization’s XIVth (14th) General Assembly, held from Aug. 18, to Aug. 27, in Brighton, United Kingdom. Prior to its formal naming, Bragg Crater was designated as Crater 102. Approval of the letter designations for the Bragg Crater system’s three satellites was granted in 2006.

On June 1, 1889, William Henry Bragg married Gwendoline Todd (July 22, 1869-), the watercolorist daughter of Sir Charles Todd (July 7, 1826-Jan. 29, 1910), British-born Australian astronomer, meteorologist and electrical engineer. The couple had three children: William Lawrence Bragg (March 31, 1890-July 1, 1971), Robert Charles Bragg (Nov. 25, 1892-Sept. 2, 1915) and Gwendolen Mary Bragg Caroe (Feb. 26, 1907-Jan. 9, 1982).

The Royal Swedish Academy of Sciences awarded the Nobel Prize in Physics in 1915 jointly to William Henry Bragg and his older son, William Lawrence Bragg. The Nobel Prize website notes that the father-son science team founded x-ray analysis of crystal structure as “a new branch of science of the greatest importance and significance.” William Henry and William Lawrence uniquely qualify as the only Nobel laureate father-son to share the same prize.

The Royal Swedish Academy’s Nov. 12, 1915, telegram informing the father-son Braggs of their award occurred approximately two and one-half months after the tragic news of the death of Robert Charles Bragg. The younger Bragg son died from wounds sustained in the First World War (July 28, 1914-Nov. 11, 1918) during the Gallipoli Campaign’s (Feb. 17, 1915-Jan. 9, 1916) Landing at Suvla Bay (Aug. 6-Aug. 15, 1915), southern European Turkey (East Thrace).

Sir William Henry’s knightship occurred in 1920. Sir William Lawrence’s knightship was conferred in 1941.

The takeaways for Bragg Crater, which honors British physicist Sir William Henry Bragg, are that craterlet-riddled impact crater occupies the lunar far side’s northeastern quadrant; that the Bragg Crater system comprises a primary crater and three satellites; that the Bragg Crater system’s namesake was awarded the 1915 Nobel Prize in Physics jointly with his older son, Sir William Lawrence; and that the Braggs remain the only father-son Nobel laureates.

Detail of Shaded Relief and Color-Coded Topography Map shows lunar far side’s Bragg Crater (center left) as lunar far side northeastern quadrant crater, located west of near side Oceanus Procellarum’s (Ocean of Storms) libration visibility along limb: 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 Charts (LAC) 36 shows the lunar far side’s Bragg Crater system of parental Bragg (center), Bragg H (center right), Bragg M (lower right) and Bragg P (lower center); 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/lac36_wac.pdf

Detail of Shaded Relief and Color-Coded Topography Map shows lunar far side’s Bragg Crater (center left) as lunar far side northeastern quadrant crater, located west of near side Oceanus Procellarum’s (Ocean of Storms) libration visibility along limb: U.S. Geological Survey, Public Domain, via USGS Astrogeology Science Center / Gazetteer of Planetary Nomenclature @ https://planetarynames.wr.usgs.gov/images/moon_farside.pdf

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