The sidereal messenger of Galileo Galilei and a part of the preface to Kepler's Dioptrics containing the original account of Galileo's astronomical discoveries (1880)
e most exact observations, contains 7000Italian miles, CFwill be 2000, and ce 1000, and the-2^th part of the whole, cf, 100 miles. Also let cfbe a diameter of the great circle which divides thebright part of the Moon from the dark part (for,owing to the very great distance of the Sun from theMoon… … 3o THE SIDEREAL MESSENGER. G c D, which represents the ray that illumines thesummit, in the point D. Then the arc ca or thestraight line c D will be 100 of such units, as c E con-tains 1000. The sum of the squares of DC, ce istherefore 1,010,000, and the square of de is equal tothis; therefore the…
Astronomy
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![An illustration from Sidereus nuncius : magna, longeque admirabilia spectacula pandens, suspiciendaque proponens vnicuique, praesertim verò philosophis, atq[ue] astronomis, quae à Galileo Galileo ... perspicilli nuper à se reperti beneficio sunt obseruata in lunae facie, fixis innumeris, lacteo circulo, stellis nebulosis, apprime verò in quatuor planetis circa Iouis stellam disparibus interuallis, atque periodis, celeritate mirabili circumuolutis; quos, nemini in hanc vsque diem cognitos, nouissimè author depraehendit primus; atque Medicea sidera nuncupandos decreuit (1610)](https://img.insideoutlibrary.com/img/200/ia-sidereusnunciusm00gali-31-11.webp)
