Galileo Galilei

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Galileo Galilei

(extended biography)

The lunar crater Galilaei is named after Galileo Galilei (15 February 1564 – 8 January 1642), one of the most renowned scientists in world history.


Galileo, the son of a Pisan musician, began his professional career as a Professor of Mathematics at the University of Pisa where he began profoundly original studies in mechanics, moving in 1592 to the University of Padua,. While there, in 1609, he heard news of the newly-invented telescope; which he was soon able to build and improve. Although expected primarily to prove valuable as a military instrument, Galileo soon turned it towards the heavens (as others undoubtedly also did), publishing his initial conclusions in the spring of 1610. Capitalizing on the renown his discoveries bought him, Galileo moved to Florence in the fall of 1610, where he served, for the rest of his life, as "Philosopher and Mathematician" to the Medici Grand Duke. Although Galileo’s fame continued to increase, he came into conflict with the authorities of the Roman Catholic church and died under house arrest at his home in Florence.

Lunar Contributions

  • Although generally regarded as one of the founders of modern science in general, Galileo is also definitely the founder of modern lunar science in particular. Although Thomas Harriot is known to have preceded him in observing the Moon through a telescope; Galileo was probably the first to understand what he was seeing, and certainly the first to publish a description of what he saw.
  • Galileo very early recognized that the pattern of light and shadow seen when the Moon was examined with the telescope resulted from the play of sunlight over a rugged and variable topography, and he used his mathematical skills to estimate the height of the features that must be involved.
  • Galileo believed the Moon was basically an airless world, although he continued to search the limb for evidence of a thin atmosphere.
  • Galileo rejected Kepler’s view that the Moon was responsible tides on Earth.
  • Late in life Galileo demonstrated an awareness of the Moon’s librations – the small rocking motions that can be observed in the face pointed towards Earth.
  • Galileo is sometimes said to have invented the modern term "crater" (as applied to features on the Moon) and is frequently said to have thought the dark areas were "seas" (mare). In fact, he called the craters "spots", and although he said that he thought that if the Earth could be viewed from space the land would appear bright and the oceans (mare) dark, he did not conclude from that that the dark areas on the Moon were actually liquid water.


A list of Galileo’s astronomically-related publications, and directions for accessing them online, can be found here.

  • Sidereus Nuncius 1610 – shows and explains the phases of the Moon and speculates about the nature of the lunar surface. Contains the first published lunar maps adequate to show recognizable(?) surface features.
    • A page of watercolor sketches thought to be by Galileo and used in the preparation of his Sidereus Nuncius were displayed as part of an exhibit celebrating 400 years of the telescope.
    • More exhibits related to Sidereus Nuncius (click on the "Related Resources" links in the lower right for digital copies)
    • An English translation (pdf) keyed to the original pagination of Sidereus Nuncius.


Biographical Resources

Web Links