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The Sidereal Messenger

First published: 1610
Pages: 86

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About this book

In the winter of 1609 and 1610, Galileo turned a telescope of his own making on the night sky and rushed into print within weeks. The little book that resulted reports mountains and craters on a Moon that was supposed to be a flawless sphere, hundreds of stars invisible to the naked eye crowding the Milky Way, and four small bodies circling Jupiter, which he named the Medicean Stars to flatter his Florentine patrons. It was the first scientific work built on telescopic evidence, and its plain drawings did more damage to the old cosmology than any argument had. This edition adds part of Kepler's preface to the Dioptrics, an early and generous response from a fellow astronomer. Free to download as a PDF or EPUB.

About the author

Galilei, Galileo, Kepler, Johannes

Galileo Galilei (1564-1642) was an Italian astronomer, physicist and mathematician whose telescopic observations broke the Ptolemaic sky apart. His defence of Copernicus brought him before the Inquisition and a life sentence of house arrest. Johannes Kepler, whose Dioptrics preface appears here, championed the findings early.

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