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One Nepōhualtzintzin (91) represented the number of days that a season of the year lasts, two Nepōhualtzitzin (182) is the number of days of the corn's cycle, from its sowing to its harvest, three Nepōhualtzintzin (273) is the number of days of a baby's gestation, and four Nepōhualtzintzin (364) completed a cycle and approximated one year.
The history of the periodic table is also a history of the discovery of the chemical elements. The first person in recorded history to discover a new element was Hennig Brand, a bankrupt German merchant. Brand tried to discover the philosopher's stone —a mythical object that was supposed to turn inexpensive base metals into gold.
The discoveries of the 118 chemical elements known to exist as of 2024 are presented here in chronological order. The elements are listed generally in the order in which each was first defined as the pure element, as the exact date of discovery of most elements cannot be accurately determined. There are plans to synthesize more elements, and it ...
The United States Secret Service (USSS or Secret Service) is a federal law enforcement agency under the Department of Homeland Security with the purpose of conducting investigations into currency and financial-payment crime, and protecting U.S. political leaders, their families, and visiting heads of state or government. [3]
The first day at Gettysburg, more significant than simply a prelude to the bloody second and third days, ranks as the 23rd biggest battle of the war by number of troops engaged. About one quarter of Meade's army (22,000 men) and one third of Lee's army (27,000) were engaged.
1932 Antielectron (or positron), the first antiparticle, discovered by Carl D. Anderson [13] (proposed by Paul Dirac in 1927 and by Ettore Majorana in 1928) : 1937 Muon (or mu lepton) discovered by Seth Neddermeyer, Carl D. Anderson, J.C. Street, and E.C. Stevenson, using cloud chamber measurements of cosmic rays [14] (it was mistaken for the pion until 1947 [15])
Discovery of Neptune. New Berlin Observatory at Linden Street, where Neptune was discovered observationally. Neptune as imaged by the Voyager 2 probe in 1989. The planet Neptune was mathematically predicted before it was directly observed. With a prediction by Urbain Le Verrier, telescopic observations confirming the existence of a major planet ...
On February 6, 57-year-old Patricia Dowd of San Jose, California became the first COVID-19 death in the United States (discovered by April 2020). She died at home without any known recent foreign travel, after being unusually sick from flu in late January, then recovering, working from home, and suddenly dying on February 6.