Physics Test 1 - Chapter 3

What three things made the heliocentric view (the model proposed by Aristarchus) of the heavens seem unlikely?

1) Went against common sense 2) Aristotle's viewpoint was the strongest and most widely accepted for the time period 3) There was no evidence of the parallax movement of the stars.

What is the ecliptic? How was the location of the ecliptic determined?

An ecliptic is the location of the moon relative to the earth when it is eclipsed. These locations are determined based upon observations of the moon.

What was Aristotle's view of the heavens like? What determined the order of the spheres?

Aristotle viewed that the heavens was that the earth was the center of the solar system. The planets assumed the order, based upon how fast it was for them to travel the sky. The shorter the time for a complete trip, the closer to earth the planet is.

How were constellations originally defined? How are they defined today?

Constellations were originally defined based upon the shapes of stars. They are now defined based upon groupings of stars.

Who was the first proponent of the heliocentric universe? Who was the modern day proponent?

Copernicus was the first proponent of the heliocentric universe. Galileo was the modern day proponent.

How did Eratosthenes measure the circumference of the earth?

Eratosthenes measured the circumference of the earth by measuring the distance between two cities. Then he measured the angle of sunlight relative to the vertical on the summer solstice. The sun was overhead in Alexandria but seven degrees away from the vertical in Syene. The ratio of 7 to 360 was equal to the ratio of the distance between the cities and the circumference.

Who won the "Battle for the Heavens" (helio vs geo) in the hearts and minds of the common people?

Galileo won the "Battle for the Heavens" in the hearts and minds of the common people.

What contribution to early astronomy was made by Hipparchus? Who used his data to make a model of the solar system?

Hipparchus made some of the first measurements of the solar system. Ptolemy used Hipparchus's results to make a model of the solar system.

How many hours changes the appearance of the sky on one day to match the sky at the same time of day a month later?

One twelfth a day, or two hours makes the same change as one month.

Who developed the first "workable" model of the solar system?

Ptolemy created the first "workable" model of the solar system.

How did Ptolemy's model account for retrograde motion?

Ptolemy's model accounts for retrograde motion through an epicycle. At a certain period of time a planet would make a circular loop and head the other direction.

Why would we say that Ptolemy's model was both accurate and fundamentally incorrect?

Ptolemy's model was correct in regards to the positioning of the planets, however the sun is actually at the center of the solar system and not the earth. The planets orbit the sun and not the earth.

What ancient Greek mathematician developed an early model of planetary motion?

Pythagoras created an early model of planetary motion.

What aspect of planetary motion is hard to model?

Retrograde motion is hard to model. Typically planets move in a east to west pattern. Retrograde motion is the westward motion of some planets relative to the fixed stars, such as mars.

Why was it ironic that Galileo was threatened with torture because he disagreed with Ptolemy's view of the universe?

The Church was following the beliefs of polytheism.

What is special about the signs of the Zodiac? What determines a person's birth sign?

The Zodiac sign is determined by what constellation lies behind the sun during a given month.

How does the appearance of the sky change during the evening or during the year?

The appearance of the night sky changes so that the stars rotate around the polar star once every 2 hours. Every month, the appearance of the stars rotate 1/12, so that when a year passes, the same amount of rotation would occur that occurs during one day.

What is the origin of the modern use of the word "revolution"

The origin of the modern use of the word "revolution" would be Copernicus' book with the same name. The word revolution as we now know it pays reference to his book where he talks about the revolving patterns of the planets relative to the sun. Copernicus' ideas were radical at the time and gave the word a modern connotation.