Sphere of fire is the name given in
Ptolemaic astronomy to the sphere intervening between, and separating, the
Earth
Earth is the third planet from the Sun and the only astronomical object known to Planetary habitability, harbor life. This is enabled by Earth being an ocean world, the only one in the Solar System sustaining liquid surface water. Almost all ...
and the
Moon
The Moon is Earth's only natural satellite. It Orbit of the Moon, orbits around Earth at Lunar distance, an average distance of (; about 30 times Earth diameter, Earth's diameter). The Moon rotation, rotates, with a rotation period (lunar ...
.
Traditional concept
Building on
Empedocles
Empedocles (; ; , 444–443 BC) was a Ancient Greece, Greek pre-Socratic philosopher and a native citizen of Akragas, a Greek city in Sicily. Empedocles' philosophy is known best for originating the Cosmogony, cosmogonic theory of the four cla ...
's vision of the world as a four-level cake of stacked fundamental elements - earth, water, air and fire - with fire at the top,
Aristotle
Aristotle (; 384–322 BC) was an Ancient Greek philosophy, Ancient Greek philosopher and polymath. His writings cover a broad range of subjects spanning the natural sciences, philosophy, linguistics, economics, politics, psychology, a ...
saw the
sublunary world as surmounted by the sphere of fire. Aristotle's conception became prevalent in the
Hellenic world, and was given a distance scale by Ptolemy: “taking the radius of the spherical surface of the Earth and the water as the unit, the radius of the spherical sphere which surrounds the air and fire is 33, the radius of the lunar sphere is 64....”.
The Middle Ages broadly inherited the concept of the
four elements of earth, water, air and fire arranged in concentric
spheres about the earth as centre: as the purest of the four elements, fire - and the sphere of fire - stood highest in the ascending sequence of the ''
scala naturae'', and closest to the superlunary world of the
aether. Dante and Beatrice in ''
The Divine Comedy
The ''Divine Comedy'' (, ) is an Italian narrative poem by Dante Alighieri, begun and completed around 1321, shortly before the author's death. It is widely considered the pre-eminent work in Italian literature and one of the greatest wor ...
'' ascended through the sphere of fire to reach the Moon, while three centuries later
Benvenuto Cellini
Benvenuto Cellini (, ; 3 November 150013 February 1571) was an Italian goldsmith, sculptor, and author. His best-known extant works include the ''Cellini Salt Cellar'', the sculpture of ''Perseus with the Head of Medusa'', and his autobiography ...
claimed in his autobiography to have bellowed so loud as to reach the sphere of fire.
The contemporary astronomer
Jofrancus Offusius estimated the distance to the sphere of fire from the earth in terms of multiples of the earth's diameter, and believed that comets emanated from the space between the sphere of fire and the moon.
New philosophy
The rise of
heliocentrism
Heliocentrism (also known as the heliocentric model) is a superseded astronomical model in which the Earth and planets orbit around the Sun at the center of the universe. Historically, heliocentrism was opposed to geocentrism, which placed t ...
had by the early seventeenth century destroyed the very foundations for the concept of the sphere of fire.
John Donne
John Donne ( ; 1571 or 1572 – 31 March 1631) was an English poet, scholar, soldier and secretary born into a recusant family, who later became a clergy, cleric in the Church of England. Under Royal Patronage, he was made Dean of St Paul's, D ...
lamented in 1611 that "The new philosophy calls all in doubt,/The element of fire is quite put out".
Nevertheless,
Paracelsians like
Robert Fludd continued as late as 1617 to present a picture of a geocentric cosmos, with the ''Elementum ignis'' still nestling immediately below the ''Sphera Lunae''.
See also
References
{{Reflist, 2}
Early scientific cosmologies