Pierre Janssen

1824 - 1907

Pierre Janssen

Pierre Jules César Janssen (22 February 1824 – 23 December 1907), also 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 111,054 page views. His biography is available in 40 different languages on Wikipedia making him the 51st most popular astronomer.

Memorability Metrics

  • 110k

    Page Views (PV)

  • 62.40

    Historical Popularity Index (HPI)

  • 40

    Languages Editions (L)

  • 10.74

    Effective Languages (L*)

  • 2.44

    Coefficient of Variation (CV)

Page views of Pierre Janssens by language


Among astronomers, Pierre Janssen ranks 52 out of 495Before him are Antony Hewish, Jérôme Lalande, Caroline Herschel, Sosigenes of Alexandria, Ahmad ibn Muhammad ibn Kathir al-Farghani, and Friedrich Georg Wilhelm von Struve. After him are Pierre Méchain, William Lassell, Gerard Kuiper, Fritz Zwicky, Ferdinand Verbiest, and Heinrich Louis d'Arrest.

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Among people born in 1824, Pierre Janssen ranks 11Before him are Gustav Kirchhoff, Jean-Léon Gérôme, Maria Alexandrovna, Eugène Boudin, Pierre Puvis de Chavannes, and Paul Broca. After him are Wilkie Collins, Carl Reinecke, William Walker, Karl-Maria Kertbeny, William Huggins, and Stonewall Jackson. Among people deceased in 1907, Pierre Janssen ranks 13Before him are Oscar II of Sweden, Hector Malot, Joris-Karl Huysmans, Alfred Jarry, Giosuè Carducci, and Asaph Hall. After him are Marcellin Berthelot, Paula Modersohn-Becker, Joseph Joachim, Jean Casimir-Perier, Mozaffar ad-Din Shah Qajar, and Robert I, Duke of Parma.

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In France

Among people born in France, Pierre Janssen ranks 827 out of 4,109Before him are Robert Nivelle (1856), Hector Guimard (1867), Charles III of Navarre (1361), Michel Piccoli (1925), Gaston Doumergue (1863), and Catherine Labouré (1806). After him are Jacques Charles (1763), Léon Bourgeois (1851), Jean Nouvel (1945), Juliette Gréco (1927), John, Duke of Berry (1340), and Paul Vidal de La Blache (1845).


Among astronomers born in France, Pierre Janssen ranks 3Before him are Charles Messier (1730) and Jérôme Lalande (1732). After him are Pierre Méchain (1744), Nicolas-Louis de Lacaille (1713), Jacques Cassini (1677), Nicolas-Claude Fabri de Peiresc (1580), Joseph-Nicolas Delisle (1688), Alphonse Borrelly (1842), Édouard Stephan (1837), Nicole-Reine Lepaute (1723), and Bernard Lyot (1897).

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