The Earth Adrif
Philolaus and Central Fire
• From the sixth century B.C. onward, the idea that the earth was a sphere, freely floating in air.
• Herodotus mentions a rumour that there exist people far up in the north who sleep six
months of the year-which shows that some of the implications of the earths roundness had already been grasped.
• Revolutionary step by a pupil of Pytagoras:
• Philolaus the first philosopher to attribute motion to our globe. The earth became air- borne.
• Philolaus placed in the center of his
roundabout “watch tower” of Zeus, also called
“the hearth of Universe” or central fire.
• This central fire is not to be confused with the sun. The central fire could never be seen.
• Philolaus inserted an invisible planet between central fire and the earth. It was a countre-
world. (Anticthon)
• Its function was, apparently, to protect
antipodes from being scorched by the central fire.
• But it is also possible –as Aristotle
contemptuously remarks- that it was invented merely to bring the number of moving in the universe up to ten, the sacred numbers of the Pytagorians.
Counter-earth and central fire
Philolaus Cosmology
• In spite of its poetic oddities, the System of Philolaus opened opened up a new cosmic perspective.
• It broke away from the geocentric tradition.
• There were also important progress.
• It separated two phenomena:
• The succession of day and night, that is diurnal rotation of the sky as a whole and,
• The annual motions of the seven wandering planets.
Aristarchus
• Last member of the Pytagorian astronomy tradition.
• The Greek Copernicus.
• Aristarchus proclaimed that the Sun was the center of the our universe.
• Reference: Arthur Koestler, The Sleepwalkers.
