Transcript Astronomy Timeline

Astronomy Timeline
How theory develops and
changes over time as new
technology allows for more
accurate observations.
Plato
(428-347 B.C)
argued that the sphere and the circle were
perfect shapes because of their symmetry
The heavens being the creation of the god
would have to be “perfect”
The heavens were assumed to contain
spheres in uniform (constant speed) and
perfect, circular motions and earth was the
center of motion (Geocentric).
Founded in 283 BC,
by 300 B.C. the Library of Alexandria is
accepted as the leading center of knowledge,
housing more than half a million books (scrolls
of parchment or leather and clay tablets).
The library of Alexandria held over half a million
documents from Assyria, Greece, Persia,
Egypt, India and many other nations. Over 100
scholars lived at the Museum full time to
perform research, write, lecture or translate and
copy documents.
http://ehistory.osu.edu/world/articles/ArticleView.cfm?AID=9
Aristarchus
Alexandria Egypt
280 BC
Introduces a competing theory
Suggests the Earth revolves
around the Sun(heliocentric).
However still believes in the idea
that all planets are perfect spheres
and travel around the sun in perfect
circular orbits and the star are fixed
on great celestial spheres .
Eratosthenes of Cyrene
(now Shahhat, Libya)
240 B.C.
He measures the circumference
of the earth with surprising accuracy.
The importance of this is to realize that
The ancients believed in a spherical
earth. However out of the Dark ages
and into the middle ages, Western
Europe believed that the earth was flat.
140 AD
• Ptolemy - Geocentric theory
Writes the Almagest which tells us that
the Western European world has
accepted the theory that the
• Earth is the center of the universe.
• Stars are fixed on celestial spheres.
• All the planets and the celestial
spheres move in perfect circular
motion.
140 AD
• Ptolemy - Geocentric theory
Most importantly, He tires to explain the
motion of Mars and other planets using
epicycles.
415 A.D.
The final destruction of the library of
Alexandria, along with the loss of
most of the knowledge stored there.
476 - 800 AD
Age of Darkness
An age of very little
intellectual advancements
due to fall of Roman empire,
barbaric intrusions and
warfare.
1492 Christopher Columbus Sails the ocean blue
(Ferdinand Magellan 1522 circumnavigates the globe 18 of 237 survive)
1543
• Copernicus
– Writes De Revolutionibus which re introduces
the competing theory to the geocentric theory
Heliocentric theory.
– Believes the sun to be the center of the
universe
• Stars are fixed on celestial spheres.
• All the planets and the celestial spheres move in
perfect circular motion.
1543
• Copernicus
Most importantly, he introduced a competing idea
for the Motion of Mars.
1551
• Leonard Digges
Invents the theodolite and,
from the writings of his son,
it was possibly used as a
telescope. Which would
make Leonard the inventor
of the first telescope.
1576
(G is 12)
• Thomas Digges
– Comments on his father’s writings (1st
telescope?)
– Puts the heliocentric model into stars of
infinite space and NOT celestial spheres.
To do this, he must have taken
astronomical measurements. Did he use
the theodolite to study the skies? None of
his writings suggest that he did. So
neither he or his father is given credit for
inventing the telescope.
1577
(G is 13)
Tyco BraheSpends 20 years of his life studying and
measuring planetary movements and
motion of stars.
Observes a comet over a year’s time.
Using Parallax, Tyco proves through
observation, measurements and
mathematics that Thomas Digges was
correct.
The stars are NOT fixed on celestial spheres.
1600
(G is 36)
• Johannes Kepler
–Uses Tyco’s data to prove that
the planets revolve in elliptical
orbits. NOT perfect circular
orbits.
1577 - 1600
It is around this time that the geocentric
Theory begins to fall apart due to accurate
observations made possible through
improvements of the tools used to make
astronomical measurements.
Stars are no longer fixed on crystal spheres.
Planets travel in elliptical orbits and not
perfectly circular orbits.
1608
(G is a famous professor at university of Pedua 44)
Hans Lippershey
is officially recorded to have
invented the telescope.
1609
• Galileo
–Invents a new and improved
model of Hans’ telescope
–Introduces a law of motion
called inertia
1609
• Galileo
• Most importantly, the
discovery of the moons
orbiting Jupiter proves that
the earth is NOT the center
around which all objects
orbit.
• Galileo was a remarkable man.
• After stating that the Sun was the center of our
universe, the church held him under house
arrest. He died under house arrest in such great
pain from arthritis that even his guards pleaded
with their superiors to give them another
assignment. Though Galileo recanted his theory
and proofs, he continued to study the planets
and sun. He died knowing that what he knew to
be true was being suppressed and he could do
nothing about it. He must have wondered on his
death bed,
• “How long before they accept the truth?”
• Good reading resources
• Galileo's Daughter: A Historical Memoir of
Science, Faith, and Love by Dava Sobel
• The Scientists: A History of Science Told
Through the Lives of Its Greatest Inventors.
By John Gribbin