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{{Use American English|date=May 2015}} Since antiquity, astronomers have progressively refined the definition of the tropical year. The entry f ...

...r designed by a commission assembled by Pope Gregory XIII in the sixteenth century."}}{{efn|Many countries that use other calendars for religious purposes use ...ays; when Russia and Greece did so (for their civil calendars) in the 20th century, the jump was 13 days. For other countries and territories, see [[List of a ...

Astronomers and great thinkers of the past were able to record observations and attempt ...one depicts Earth in the day.<ref name=DatEA>Source: ''Dante and the Early Astronomers'' by M. A. Orr, 1913.</ref>]] ...

...peared throughout history, including the work of [[Desargues]] in the 17th century, all the way back to the implicit use of [[spherical geometry]] to understa ...the theory of [[manifold]]s and [[Riemannian geometry]]. Later in the 19th century, it appeared that geometries without the [[parallel postulate]] ([[non-Eucl ...

...actions. The system became the standard of France and Europe within half a century. Other measures with unity ratios<ref group="Note">ratios of 1 between mag ...ts for length, mass and time. Advances in [[electromagnetism]] in the 19th century necessitated additional units to be defined, and multiple incompatible syst ...

Eventually,<ref>The Mesopotamian (modern-day Iraq) astronomers recorded astronomical observations with the naked eye, more than 3500 years [[Galileo]], [[Isaac Newton|Newton]], and most people up until the 20th century thought that time was the same for everyone everywhere. This is the basis f ...

{{Short description|English theoretical physicist (1942–2018)}} '''Stephen William Hawking''' (8 January 1942&nbsp;– 14 March 2018) was an English [[theoretical physics|theoretical physicist]], [[cosmologist]], and author ...

...ultural water to nearly 40,000&nbsp;people.<ref>{{cite journal |last= Ward English |first= Paul |title= The Origin and Spread of Qanats in the Old World |jour ...or [[panemone windmill]] first appeared in [[Greater Iran]] during the 9th century.<ref>Glick, Thomas F., Steven Livesey, and Faith Wallis. Medieval science, ...

{{Use British English|date=August 2024}} ...Neptune|remaining moons]] were located telescopically until the 20th&nbsp;century. ...

...]] that is able to [[flight|fly]] by gaining support from the [[air]].<!-- English word "aircraft" is singular and plural with no "s". See also the link to Wi ...foil]]''' – An airfoil ([[American English]]) or '''aerofoil''' ([[British English]]) is the cross-sectional shape of a [[wing]], blade (of a [[Propeller (aer ...