Sphere of fire is the name given in
Ptolemaic astronomy
In astronomy, the geocentric model (also known as geocentrism, often exemplified specifically by the Ptolemaic system) is a superseded description of the Universe with Earth at the center. Under most geocentric models, the Sun, Moon, stars, an ...
to the sphere intervening between, and separating, the
Earth
Earth is the third planet from the Sun and the only astronomical object known to harbor life. While large volumes of water can be found throughout the Solar System, only Earth sustains liquid surface water. About 71% of Earth's surfa ...
and the
Moon
The Moon is Earth's only natural satellite. It is the fifth largest satellite in the Solar System and the largest and most massive relative to its parent planet, with a diameter about one-quarter that of Earth (comparable to the width of ...
.
Traditional concept
Building on
Empedocles
Empedocles (; grc-gre, Ἐμπεδοκλῆς; , 444–443 BC) was a Greek pre-Socratic philosopher and a native citizen of Akragas, a Greek city in Sicily. Empedocles' philosophy is best known for originating the cosmogonic theory of the ...
'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 (; grc-gre, Ἀριστοτέλης ''Aristotélēs'', ; 384–322 BC) was a Greek philosopher and polymath during the Classical period in Ancient Greece. Taught by Plato, he was the founder of the Peripatetic school of phil ...
saw the
sublunary world as surmounted by the sphere of fire. Aristotle's conception became prevalent in the
Hellenic world
Ancient Greece ( el, Ἑλλάς, Hellás) was a northeastern Mediterranean civilization, existing from the Greek Dark Ages of the 12th–9th centuries BC to the end of classical antiquity ( AD 600), that comprised a loose collection of cult ...
, 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
Classical elements typically refer to earth, water, air, fire, and (later) aether which were proposed to explain the nature and complexity of all matter in terms of simpler substances. Ancient cultures in Greece, Tibet, and India had simi ...
of earth, water, air and fire arranged in concentric
spheres
The Synchronized Position Hold Engage and Reorient Experimental Satellite (SPHERES) are a series of miniaturized satellites developed by MIT's Space Systems Laboratory for NASA and US Military, to be used as a low-risk, extensible test bed for the ...
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
The great chain of being is a hierarchical structure of all matter and life, thought by medieval Christianity to have been decreed by God. The chain begins with God and descends through angels, humans, animals and plants to minerals.
The great c ...
'', and closest to the superlunary world of the
aether. Dante and Beatrice in ''
The Divine Comedy
The ''Divine Comedy'' ( it, Divina Commedia ) is an Italian narrative poem by Dante Alighieri, begun 1308 and completed in around 1321, shortly before the author's death. It is widely considered the pre-eminent work in Italian literature an ...
'' ascended through the sphere of fire to reach the Moon, while three centuries later
Benvenuto Cellini 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 had by the early seventeenth century destroyed the very foundations for the concept of the sphere of fire.
John Donne
John Donne ( ; 22 January 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 ...
lamented in 1611 that "The new philosophy calls all in doubt,/The element of fire is quite put out".
Nevertheless,
Paracelsians
Paracelsianism (also Paracelsism; German: ') was an early modern medical movement based on the theories and therapies of Paracelsus.
It developed in the second half of the 16th century, during the decades following Paracelsus' death in 1541, a ...
like
Robert Fludd
Robert Fludd, also known as Robertus de Fluctibus (17 January 1574 – 8 September 1637), was a prominent English Paracelsian physician with both scientific and occult interests. He is remembered as an astrologer, mathematician, cosmologis ...
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