Week 11: How we come to realize that the earth is not the center of the universe

Question 1

believed that everything was related to mathematics and that through mathematics everything could be predicted and measured in rhythmic patterns or cycles

Answer 1

Pythagoras

Question 2

a Greek term meaning ’wanderer’

Answer 2

planet

Question 3

also one of the first to think that the Earth was round, a theory that was finally proved around 330BCE by Aristotle.

Answer 3

pythagoras

Question 4

Aristotle believed that the only eternal motion is circular with a constant speed, the motions of the planets must be circular.

Answer 4

The Principal of Uniform Circular Motion

Question 5

a citizen of Egypt which was under Roman rule during Ptolemy’s lifetime. During his lifetime he was a mathematician, astronomer, and geographer. His theories dominated the world’s understanding of astronomy for over a thousand years

Answer 5

Claudius Ptolemy

Question 6

as outlined in the Almagest, the Universe according to Ptolemy was based on five main points:

Answer 6

1) the celestial realm is spherical,
2) the celestial realm moves in a circle,
3) the earth is a sphere,
4) the celestial realm orbit is a circle centered on the earth,
5) earth does not move

Question 7

some of the planets appeared to move in the opposite direction of their normal movement. This reverse direction movement is referred to as

Answer 7

retrograde motion

Question 8

The Ptolemaic system had circles within circles that produced

Answer 8

epicycles

Question 9

sun-centered design

Answer 9

heliocentric

Question 10

the year Copernicus introduced a sun-centered design (heliocentric), that Ptolemy’s astronomy was seriously questioned and eventually overthrown.

Answer 10

1543

Question 11

Kepler’s Laws of Planetary Motion

Answer 11

1. The orbits of the planets are elliptical.
2. An imaginary line connecting a planet and the sun sweeps out equal areas during equal time intervals.(Therefore, the earth’s orbital speed varies at different times of the year. The earth moves fastest in its orbit when closest to the sun and slowest when farthest away.) Kepler’s Second Law of Planetary Motion was calculated for Earth, then the hypothesis was tested using data for Mars, and it worked!
3. Kepler’s Third Law of Planetary Motion showed the relationship between the size of a planet’s orbit radius, R(12the major axis), and its orbital period, T.R2=T3This law is true for all planets if you use astronomical units (that is, distance in multiples of earth’s orbital radium and time in multiples of earth years). Kepler’s three laws replaced the cumbersome epicycles to explain planetary motion with three mathematical laws that allowed the positions of the planets to be predicted with accuracies ten times better than Ptolemaic or Copernican models.

Question 12

provided the crucial observations that proved the Copernican hypothesis, and also laid the foundations for a correct understanding of how objects moved on the surface of the earth and of gravity. One could, with considerable justification, view Galileo as the father both of modern astronomy and of modern physics

Answer 12

Galileo Galilei

Question 13

the dominant and highly supported theory of the origin of the universe. It states that the universe began from an initial point which has expanded over billions of years to form the universe as we now know it

Answer 13

big bang theory

Question 14

In 1922 ___ found that the solutions to Einstein’s general relativity equations resulted in an expanding universe. Einstein, at that time, believed in a static, eternal universe so he added a constant to his equations to eliminate the expansion. Einstein would later call this the biggest blunder of his life.

Answer 14

Alexander Friedman

Question 15

In 1924, ___ was able to measure the distance to observed celestial objects that were thought to be nebula and discovered that they were so far away they were not actually part of the Milky Way (the galaxy containing our sun). He discovered that the Milky Way was only one of many galaxies.

Answer 15

Edwin Hubble

Question 16

In 1927 ___ a physicist, suggested that the universe must be expanding. Lemaitre’s theory was supported by Hubble in 1929 when he found that the galaxies most distant from us also had the greatest red shift(were moving away from us with the greatest speed). The idea that the most distance galaxies were moving away from us at the greatest speed was exactly what was predicted by Lemaitre

Answer 16

Georges Lemaitre

Question 17

What year did Lemaitre went further with his predictions and by extrapolating backwards, found that the matter of the universe would reach an infinite density and temperature at a finite time in the past (around 15 billion years)? This meant that the universe must have begun as a small, extremely dense point of matter.

Answer 17

in 1931

Question 18

predicted that new matter was created which made it appear that the universe was expanding but that the universe was constant

Answer 18

steady state theory

Question 19

who coined the term “Big Bang Theory” which he used as a derisive name for Lemaitre’s theory?

Answer 19

Hoyle

Question 20

the major advocate of the Big Bang theory

Answer 20

George Gamow

Question 21

predicted that the expansion of the universe would cool the original radiation so that now the radiation would be in the microwave range.

Answer 21

Gamow

Question 22

The temporary apparent motion of a body in a direction opposite to that of the motion of most members of the solar system

Answer 22

retrograde motion

Question 23

A construct of the geocentric model of the solar system which was necessary to explain observed retrograde motion. Each planet rides on a small epicycle whose center in turn rides on a larger circle

Answer 23

epicycles

Question 24

The heliocentric model of astronomy is the theory that places the sun at the center of the solar system, with all the planets orbiting around it.

Answer 24

heliocentric

Question 25

A theory that deduces a cataclysmic birth of the universe from the observed expansion of the universe, cosmic background radiation, abundance of the elements, and the laws of physics.

Answer 25

big bang theory