Transcript intro.phys.psu.edu

Heliocentrism
Alex Paradero
Xinyi Ma
Jinjin Li
Xuanwei Zhang
Yesterday’s News
● In the year 150 AD, Claudius Ptolemy (c. 90 AD - 168 AD) devised a
model stating that Earth is stationary and located at the center of the
universe (Geocentrism).
● The model stated that Earth is eccentric, meaning that the Earth is slightly
off-center. This explained the lengths of the seasons and brightness.
● Ptolemy theorized that planets orbits in a circular motion; called an
epicycle, and epicycles orbit an even larger circle (known as the deferent)
around the Earth.
● This theory was accepted until around the 16th century because it
explained many Greek observations.
What Did It Look Like?
Epicycles
Planetary Order
Pioneer of Heliocentrism
●
In 315 BCE, Aristarchus was an ancient Greek astronomer, who first acclaimed that
the sun is the center of the universe. (Heliocentrism)
●
He calculated the distance between the Sun and the Earth is 19 times the distance
of the Moon and the Earth. When he calculated the width of the Earth's shadow
during the eclipse, he found the diameter of the Earth is three times of the moon’s.
●
Aristarchus thought that the large star could not rotate with the small star, and if the
Earth and the other stars rotated around the sun, celestial motion could be easily
understood.
●
However, his hypothesis was opposed by others because it violated the authority of
religions and lacked of evidence (technology) to support it.
Successor of Heliocentrism
●
After thousands of years, in 1543, Copernicus
published De Revolutionibus Orbium Coelestium,
which illustrate the same idea with Aristarchus with
systematical explanation about the Heliocentrism.
●
Copernicus observed the stars at different times and
different places from the Earth. He found that each
star will have many different orbitals, which made
him realize the Earth might not be in the center of
the universe.
●
Within 20 years of observations, Copernicus found
that only the change of sun's orbital was not
obvious, which could prove that the distance
between the Earth and the Sun does not change.
And the sun could be the center of the universe.
What Does it Look Like?
Heliocentrism
●
There is not a common center of all celestial
orbits or celestial.
●
Earth is the center lunar orbit, not the center
of the universe;
●
All the stars are moving around the sun, and
the center of the universe is near the sun;
●
The distance between the Sun to the Earth
are extremely far away.
●
Any motion of stars, being seen in the sky,
are caused by the movement of the Earth.
How Did it Impact the
World?
Scientifical
Modern model of galaxy
Cultural
Sparked controversy
Scientifical
●
Erasmus Reinhold (1511-1553) made extensive corrections to De Revolutionibus
and calculated the Tabulae Prutenicae (1551), which were more accurate than the
Alfonsine Tables. This was the first set of practical planetary tables based on
Copernicus's theory.
●
Galileo's discovery of four satellites orbiting Jupiter (1610) contradicted the widely
held belief that Earth was the center of rotation for all celestial bodies, and his
observation of mountains and depressions on the lunar surface refuted the
Aristotelian notion that the Moon was a perfect sphere. His discovery of sunspots
and the phases of the Venus also removed a serious objection to Copernican
heliocentrism.
Scientifical
●
Johannes Kepler embraced Copernicanism after attending Mästlin's lectures on the
superiority of Copernicus's cosmology. After secured control of Tycho Brahe’s
incomparable data set and spent the next eight years devising various geometrical
schemes to account for the observations of Mars. Kepler finally determined:
❖ The path of the planets about the sun is elliptical in shape, with the center of the
sun being located at one focus.---- Kepler's First Law, also The Law of Ellipses
❖ An imaginary line drawn from the center of the sun to the center of the planet will
sweep out equal areas in equal intervals of time. ---- Kepler's Second Law, also
the Law of Equal Areas
❖ The ratio of the squares of the periods of any two planets is equal to the ratio of
the cubes of their average distances from the sun. ---- Kepler's Third Law, also
the Law of Harmonies
Cultural
Regarding Religion
●
Because Heliocentrism disproved the Church’s statement that Earth is the center of
the Universe, the Church regarded Copernicus and Galileo as sinners and
Heliocentrism works were not allowed to be published.
●
A type of war between science and religion was in play but there would be more
casualties on the side of science. Scientific observation proved that Heliocentrism is
more accurate.
●
The victory of Heliocentrism encouraged more scientists to follow the observation
and think without relying on the religion. And it also inspired scientists to raise views
different from the mainstream.
Cultural
Copernican Revolution
●
The Copernican Revolution, has been widely used as a metaphor for descriptions
of modernity. A notable case was the use of this comparison by Kant in his
Critique of Pure Reason to explain the effect in epistemology of his new
philosophy.
●
The phrase is now widely used to signify a simple change of perspective.
Works Referenced
http://www.universetoday.com/32607/geocentric-model/
http://galileo.rice.edu/sci/theories/ptolemaic_system.html
http://www.britannica.com/EBchecked/topic/482079/Ptolemaic-system
http://en.wikipedia.org/wiki/De_revolutionibus_orbium_coelestium
Science and Its Times, Stephen D. Norton, 2001, Page 318-321
http://www.physicsclassroom.com/class/circles/Lesson-4/Kepler-s-Three-Laws
http://en.wikipedia.org/wiki/Copernican_Revolution_(metaphor)
http://www.studentpulse.com/articles/533/copernicus-galileo-and-the-churchscience-in-a-religious-world