Galileo Galileo (1564-1642)

Galileo Galileo (February 15, 1564 - January 8, 1642)

One of the first who used a telescope (a term he coined in April, 1611) to observe the skies in late 1609, and the first to publish his observation to a wider audience; a summary of the first discoveries was published in his famous Sidereus Nuncius (Siderial Messenger) in May 1610. His first telescope had a free aperture of 16 mm and magnification of 21. Discovered many phenomena:

November 30 to December 10, observations of the Moon. Discovers "mountains" (and craters).
November XX, 1609, Milky Way consists of stars.
1609, numerous faint stars, e.g. in Orion's Sword (but failed to perceive the Orion Nebula) and in the Pleiades (M45).
1609, Praesepe, M44, is a star cluster.
January 7, 1610, 3 moons of Jupiter; January 15, 4th moon. See Galileo's discovery of Jupiter's moons.
July 1610, strange appearance of Saturn (suggestions caused by the Rings)
December 1610, phases of Venus.
May 1611, sunspots - Galileo's sunspot drawings.
February 1617, three stars of the Trapezium cluster in M42 (without noting the Orion Nebula).
Pre-discovery sighting of Neptune in 1612.

Note: Some of these discoveries were independent rediscoveries, e.g. Thomas Harriot discovered the mountains on the Moon and sunspots earlier.

Previously, Galileo had observed and studied the "New Star" of 1604 (Kepler's supernova).

Posthumous honors are numerous and include the naming of asteroid (697) Galilea, (discovered February 14, 1910 by J. Helffrich in Heidelberg, provisionally named 1910 JO and, from independent sightings, A910 DA, 1945 GE, and 1979 FL2), Moon Crater Galilaei (10.5N, 62.7W, 15.0 km diameter, named 1935), Mars Crater Galilaei (5.7N, 27.0W, 137.3 km, named 1973) and "Galileo Regio" on Jupiter's "Galilean" Moon Ganymede, the naming of the Galileo Jupiter Orbiter spacecraft, as well as trivial things like street names, e.g. in Paris, France: Rue Galilée, and in Munich, Germany: Galileiplatz.

Links

Galileo matters in the web
The Galileo Project - Galileo Biographical data and references (Rice University)
Galilei short biography (ESA)
Galileo Galilei Museum within the Institute and Museum of the History of Science (IMSS) of Florence, Italy, including items like two of Galileo's telescopes (of 16mm and 26mm free aperture).
Galileo biography, Sun Education page, Hiogh Altitude Observatory
Galileo Galilei biography, Biographies of Mathematicians, University of St. Andrews, Scotland
Some Galileo Galilei info, Yann Pothier
Asteroid 697 Galilea (1910 JO) (NEO/JPL)

References

Kenneth Glyn Jones, 1968. The Search for the Nebulae -- II. Journal of the British Astronomical Association, Vol. 78, No. 5 (1968), p. 360-368. Section on Galileo: p. 362-363. Reprinted in: The Search for the Nebulae. Chalfont St. Giles, 1975.
Kenneth Glyn Jones, 1991. Messier's Nebulae and Star Clusters. 2nd ed, Cambridge University Press, pp. 321-2. [ADS: 1991mnsc.book.....J].

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