astro exam 2 (Unit 4 Copernicus)

Dante (1300 CE)

he made drawings which showed the location of
heaven and hell in the Aristotelian Universe based on theological teachings of Thomas Aquinas; this became one of the foundations of the church at that time.

Copernicus (1473-1543)

he was the first to propose a comprehensive Sun-centered (heliocentric) model of the Universe that became widely accepted

true “renaissance man” (math, astronomer, physician, polygot, classics scholar, etc.)

Copernicus was bothered because Ptolemy’s model was very complex and aesthetically unpleasant

The Commentariolus

Copernicus wrote a 40-page outline of his ideas and circulated it privately to his friends, it had seven propositions:

1. celestial bodies do not all revolve around a single point

2. earth is only the center of the lunar sphere (moon’s orbit)

3. all other spheres rotate around the sun (which is therefore the center of the universe)

4. the distance between the earth and the sun is an insignificant fraction of the distance to the stars

5. the stars apparent daily motion is caused by the daily rotation of the earth

6. earth is moved in a sphere around the sun

7. earth’s orbital motion around the sun causes the retrograde motions of the planets

parallax

nearby stars should move with respect to more distant ones, caused by a heliocentric universe or when the earth moves around the sun every year

a common critique of Aristarchus’ model, one Copernicus anticipated in the Commenteriolus saying parallax is very hard to see only if all stars are very far away

how do the Ptolemaic and the Copernican systems make different predictions about the phases of the inner planets?

In the Ptolemaic system, Venus will never show a half, gibbous, or full phase. Venus will only go through a new or crescent phase.

In the Copernican system, Venus will go though all phases.

Since these phases cannot be seen with the naked eye, the resolution of this problem had to wait for Galileo’s use of his telescope to view Venus

Although most scholars were impressed by Commentariolus and the elegance of Copernicus’ model, why was he reluctant to publish his findings?

he was a bit of a perfectionist, and he was afraid of being criticized or accused of heresy

Digges (1546-1595)

one of the first to seriously introduce the concept of infinity into a model of the Universe

introduced the concept of an infinite Copernican Universe

this idea created a major religious controversy - if the universe is infinite, where is heaven? were the stars heaven?

Bruno (1548-1600)

he was the first to suggest that we live in a Universe with the Sun not at its center and that each star (possibly an infinite number of them) represent different solar systems

a member of the Catholic clergy

introduced many modern ideas

• distinguished between the earth and the planets known at the time and the entire universe, which consisted of countless worlds

• suggested that life exists on other planets

primarily a mystic, not scientific

church condemned him, but he remained religious and claimed there was no limit to the power of god

Bruno was burned at the stake in 1600 for espousing these ideas