The history of the discovery of M42

While visible as nebulous patch to the naked eye even under moderate conditions, the Orion Nebula seems to have escaped pre-telescopic detection; only the bright star Theta1 Orionis, which is situated within the nebula, was wellknown to ancient and medevial astronomers. Even Galilei didn't mention it, although he detected a number of stars in and around it during his first telescopic observations in 1610, and in 1617, found the three brightest stars of the Trapezium cluster.

A considerable number of consequent independent discoveries of this nebula followed the invention of telescope:

Nicholas-Claude Fabri de Peiresc, a French lawyer, probably found it first, on November 26, 1610, with his telescope. See his discovery observations.
Jesuit astronomer Johann Baptist Cysatus of Lucerne (1588-1657) independently discovered it in 1611, published in 1619 in his Mathemata astronomica de cometa anni 1618 (Cysatus 1619).
Giovanni Battista Hodierna discovered it somewhen before 1654, and created the first preserved drawing, or sketch, of the nebula (Hodierna 1654).

All these discoveries didn't get publicly known, but were forgotten for a considerable period of time. Consequently, the independent rediscovery by Christiaan Huygens of 1656 (Huygens 1659) was longly considered original, e.g. by Edmond Halley, Philippe Loys de Cheseaux and Charles Messier.

It was not before 1854 that Rudolf Wolf found and published Cysatus' discovery (Wolf 1854). Guillaume Bigourdan recovered Peiresc's original discovery in 1916 (Bigourdan 1916), also referring to Cysatus' finding, while Hodierna's work was rediscovered only in the 1980s (Serio et.al. 1985).

References:

Guillaume Bigourdan, 1916. La découverte de la nébuleuse d'Orion (N.G.C. 1976) par Peiresc. Comptes Rendus, Vol. 162, pp. 489-490.
Johann Baptist Cysatus, 1619. Mathemata astronomica de cometa anni 1618. Lucerne.
Giovanni Battista Hodierna, 1654. De systemate orbis cometici, deque admirandis coeli characteribus [About the systematics of the cometary orbit, and about the admirable objects of the sky]. Palermo.
Christiaan Huygens, 1659. Systema Saturnium.
G.F. Serio, L. Indorato and P. Nastasi, 1985. G.B. Hodierna's Observations of Nebulae and his Cosmology. Journal of the History of Astronomy, Vol. XVI, No. 45, p. 1-36 (February 1985).
Rudolf Wolf, 1854. Ueber den Nebelfleck im Orion. Astronomische Nachrichten, Vol. 38, No. 859, col. 109/110.

Hartmut Frommert
Christine Kronberg
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Last Modification: March 18, 2006