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Pierre Janssen

1824 - 1907

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Pierre Jules César Janssen (22 February 1824 – 23 December 1907), usually known as Jules Janssen, was a French astronomer who, along with English scientist Joseph Norman Lockyer, is credited with discovering the gaseous nature of the solar chromosphere, and with some justification the element helium. Read more on Wikipedia

Since 2007, the English Wikipedia page of Pierre Janssen has received more than 158,102 page views. His biography is available in 43 different languages on Wikipedia (up from 41 in 2019). Pierre Janssen is the 139th most popular astronomer (down from 65th in 2019), the 1,883rd most popular biography from France (down from 1,011th in 2019) and the 9th most popular French Astronomer.

Pierre Janssen is most famous for discovering the element helium.

Memorability Metrics

  • 160k

    Page Views (PV)

  • 56.73

    Historical Popularity Index (HPI)

  • 43

    Languages Editions (L)

  • 5.83

    Effective Languages (L*)

  • 3.86

    Coefficient of Variation (CV)

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Among astronomers, Pierre Janssen ranks 139 out of 531Before him are Johann Franz Encke, John Louis Emil Dreyer, Alphonse Borrelly, Williamina Fleming, Cornelis Johannes van Houten, and Antonie Pannekoek. After him are Joseph-Nicolas Delisle, Luigi Ferdinando Marsili, Maria Mitchell, Annie Jump Cannon, Nur ad-Din al-Bitruji, and Giovanni Battista Hodierna.

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Among people born in 1824, Pierre Janssen ranks 27Before him are Tokugawa Iesada, Ludwig Büchner, Johann Wilhelm Hittorf, Nana Sahib, Leland Stanford, and Princess Francisca of Brazil. After him are Peter Cornelius, Louis II, Grand Duke of Baden, Jozef Israëls, George MacDonald, Michael Madhusudan Dutt, and Gustave Boulanger. Among people deceased in 1907, Pierre Janssen ranks 30Before him are Carola of Vasa, Henry Steel Olcott, Qiu Jin, Léo Taxil, Kurmanjan Datka, and Marie of Saxe-Altenburg. After him are Stanisław Wyspiański, Hermann Carl Vogel, Konstantin Pobedonostsev, Joseph Hellmesberger Jr., William Le Baron Jenney, and Nicolae Grigorescu.

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In France

Among people born in France, Pierre Janssen ranks 1,883 out of 6,011Before him are Youri Djorkaeff (1968), Joseph Fesch (1763), Louis Victor, Prince of Carignano (1721), Philip II, Count of Nevers (1389), Pierre Beauchamp (1631), and Robert Brasillach (1909). After him are Peter the Venerable (1092), Robert de Boron (1110), Philippe de Commines (1447), Maurice Duruflé (1902), Roland Petit (1924), and Joseph-Nicolas Delisle (1688).


Among astronomers born in France, Pierre Janssen ranks 9Before him are Nicolas-Louis de Lacaille (1713), Pierre Méchain (1744), Jacques Cassini (1677), Nicolas-Claude Fabri de Peiresc (1580), Édouard Stephan (1837), and Alphonse Borrelly (1842). After him are Joseph-Nicolas Delisle (1688), Guillaume Bigourdan (1851), Bernard Lyot (1897), Nicole-Reine Lepaute (1723), Jean Chacornac (1823), and Jean Picard (1620).