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The dates indicate the true age of the minerals only if the rocks have not been subsequently altered (see rubidium–strontium dating). [ 28 ] [ 29 ] Rubidium-82 , one of the element's non-natural isotopes, is produced by electron-capture decay of strontium-82 with a half-life of 25.36 days.
Shortly after the discovery of rubidium, Crookes found a new green line in a selenium sample; later that year, Lamy found the element to be metallic. [133] 49 Indium: 1863 F. Reich and T. Richter: 1864 T. Richter Reich and Richter first identified it in sphalerite by its bright indigo-blue spectroscopic emission line. [134]
Robert Wilhelm Eberhard Bunsen (German:; 30 March 1811 [a] – 16 August 1899) was a German chemist.He investigated emission spectra of heated elements, and discovered caesium (in 1860) and rubidium (in 1861) with the physicist Gustav Kirchhoff. [11]
Central America and Latin America: 1799–1803 Alexander von Humboldt: Northwest Plateau of North America: 1804–1806 Lewis and Clark Expedition: The North Magnetic Pole: 1831-06-01 James Clark Ross: Australia: c. 1640 Makassar People before. Explored by Abel Tasman. Interior of Africa 1851–1873 David Livingstone: The Burke and Wills ...
The following dates are approximations. 700 BC: Pythagoras's theorem is discovered by Baudhayana in the Hindu Shulba Sutras in Upanishadic India. [18] However, Indian mathematics, especially North Indian mathematics, generally did not have a tradition of communicating proofs, and it is not fully certain that Baudhayana or Apastamba knew of a proof.
The exploration of North America by European sailors and geographers was an effort by major European powers to map and explore the continent with the goal of economic, religious and military expansion. The combative and rapid nature of this exploration is the result of a series of countering actions by neighboring European nations to ensure no ...
The exploration of the Americas includes: Exploration of North America. Age of Discovery § Exploring North America; Timeline of the European colonization of North America; Colonial history of the United States; Exploration of South America. Age of Discovery#Inland Spanish expeditions (1519–1532) European colonization of the Americas
Christopher Columbus [b] (/ k ə ˈ l ʌ m b ə s /; [2] between 25 August and 31 October 1451 – 20 May 1506) was an Italian [3] [c] explorer and navigator from the Republic of Genoa [3] [4] who completed four Spanish-based voyages across the Atlantic Ocean sponsored by the Catholic Monarchs, opening the way for the widespread European exploration and colonization of the Americas.