Peter Florian
Mr. Percival – Period 5
Astronomy
10 October 2014
Astronomy Bio
Eudoxus (roughly translated to “honored”) and Callipus (a
student of Eudoxus) were both great astronomers who contributed greatly to our
current understanding. Eudoxus was made famous from his planetary model which
attempted to explain the retrograde motion of the planets. However this was not
the only thing that Eudoxus was famous for, Eudoxus was also a famous mathematician.
Callipus studied under Eudoxus at the academy of plato. He was famous for
adding on to Eudoxus’ model of the known universe.
Eudoxus was born in 408 BC and he studied under the
School of Plato. Eudoxus’ father loved to look up at the stars and that is what
got him interested in astronomy. Eudoxus then ventured to Tarentum to learn mathematics
from Archytas. While in Italy he went to Sicily to study medicine under Philiston.
Eudoxus dropped out of the School of Plato due to a disagreement. In order to
continue to continue hearing the lessons Eudoxus walked 7 miles each way just
to hear Plato’s speeches. During his travels Eudoxus gathered many students of
his own including Callipus. Rumor has it that he might have even taught Aristotle.
He was famous for developing the astronomical globe and a model that helps to
explain the retrograde motion of the planets.
Eudoxus’ system helped to explain the apparent retrograde
motion of the planets by adding orbits inside the orbits of the planets around
the earth. At the time of Eudoxus everyone thought that the universe was
perfect and if it was perfect than the orbits had to be comprised of circular
orbits. Elliptical orbits were not discovered until Johannes Kepler published
his laws of planetary motion. Eudoxus explained the orbits by making the
planets follow and orbit that follows another orbit around the Earth. People
still had a geocentric model because at the time people still believed that the
Earth was the center of the universe. The moon was assigned three spheres; one
that explained the rising and setting of the moon, a second that explains the
monthly motion of the moon and the third that describes the motion of the lunar
nodes. The sun was assigned three spheres and the five visible planets were
assigned four spheres each. The major flaw in this system was the fact that it
could not explain the varying brightness of the planets. Even though this model
is really inaccurate it was a great leap forward in the field of astronomy
because it was the first attempt to mathematically explain the motion of the
planets.
Callipus was born
in the 370 BC at Cyzicus and studied under Eudoxus at the Academy of Plato.
Callipus observed the movement of planets and tried to explain them by
expanding on Eudoxus’ model of the solar system. Callippus improved on Eudoxus’
model by adding more spheres. In total he added seven: two for the sun, two for
the moon and one for each Mercury, Venus, and Mars. This helped to more accurately
describe and predict the motion of the planets. He also discovered the solar
anomaly which is the variation in the length of seasons.
Both of these astronomers took giant steps in the field
of astronomy to help explain what we observed from the Earth. While both of
these models were extremely inaccurate, both were the first attempts to
understand retrograde motion. With their limited resources both of these
astronomers produced amazing results that greatly affected the way we see the
universe today. It is because of people like these two that we learned that we
are not actually the center of the universe. All in all we need more people
like Eudoxus and Callippus in modern day to try to question what is thought to
be known and fully explain it through careful observation.
