RANDY L. PHELPS

This is the History of Astronomy Module

_______________________________________________________________________________________________________________

Procedure

1.  For this module, please look through the "lecture" notes for "Early Astronomy", Ptolemy/Copernicus/Brahe and "Kepler/Galileo/Newton".  These notes contain the material, in condensed form, that I will expect you to become familiar with.  I am sure you will have questions about the material, especially since it is presented in the form of lecture notes.  To help you fill in the blanks, I have added web links within the lecture notes that you can follow, in order to gain further insight into the material. 

______________________________________________________________________________________________________________

Upon completion of this module, you should be comfortable with the following material:

• Definitions and Concepts: Crystalline Spheres, retrograde motions, epicyles, deferents, ecliptic, properties of orbits
• Early astronomy: e.g., Eratosthenes - what did he and other people do? Why was the Earth known to be round in the ancient world? How do these items affect our interpretation of Columbus and his journey?
• The Geocentric Model: What are the important features of the geocentric model, and why were they needed. Who were the important players in its development? Why was the model favored for so long? What were its problems?  What specific predicitions did it make and why were they significant?
• The Heliocentric Model: What are the important features of the heliocentric model, and why were they needed. Who were the important players in its development? Why did this model gain acceptance over time? Why did it take so long for to gain acceptance?
• Planetary Orbits: Who were Brahe, Kepler, Galileo and Newton? What were their major contributions to our understanding of planetary motions? 
• Kepler's Laws: What are Kepler’s Laws?  The usefulness of Kepler’s 3^rd Law in its three forms.
• Newton’s Laws. The Law of Gravity.  What quantities go into the description of gravity, according to Newton?  If one changes one of the quantities, how does the force of gravity change?  How can it be shown that Gravity is a universal force?  Why is this important?  How does this differ from Aristotle's view of physics?

______________________________________________________________________________________________________________

Upon completion of this module, you should be able to answer these, and similar questions:

Basic Concepts

• How often, on average, does a total eclipse of the Sun occur at any location on the Earth?
• How often, on average, does a total eclipse of the Sun occur at a specific location on the Earth?
• What phase must the Moon be in for a total eclipse of the Sun to occur?
• What phase must the Moon be in for a total eclipse of the Moon to occur?
• What is retrograde motion?
• Why did retrograde motion play such an important role in the complexity of the Geocentric model?
• What are eppicycles and deferents?
• According to the Geocentric model, what specific constraint was imposed on the Earth and the orbits of Venus and the Sun?
• According to Aristotle, what was physics like on the Earth, compared to that in the heavens?
• Why was the heliocentric model of the cosmos developed by Copernicus not accepted at first?
• What specific prediction did the Geocentric model make regarding Venus?
• What observation by Galileo "put the nail in the coffin" of the geocentric model of the cosmos?
• How did Ptolemy's geocentric model make the planets undergo retrograde motion?
• What observations, thousands of years ago, led people to know that the Earth was round?
• Briefly describe the technique that led Eratosthenes to determine the size of the Earth?
• The Geocentric model ran into severe trouble because of what observation(s) by Tycho Brahe?
• What is the Astronomical Unit?
• What are Kepler's 3 Laws of Planetary Motion?
• If two planets have orbital periods of 1 year (planet 1) and 11 years (planet 2), how do the semi-major axes of their orbits compare? 
• Which planet would orbit the Sun with a longer period, one with a semimajor axis of 2.5 AU, or one with a semimajor axis of 3.5 AU?
• What are Newton's Laws of Motion?
• What quantities go into Newton's Law of Gravity?

• During a total lunar eclise, theMoon appears a deep red color.  Why?
• If the Moon and the Sun subtend the same angle on the sky, and the moon is 400 times closer than is the Sun, how do their distances from the Earht compare?
• Explain how and why Kepler’s 3^rd Law can be used to determine the mass of:  A. The Sun;   B. Jupiter, which has a number of natural satellites (moons), including four that were discovered by Galileo;   C. Venus, which has no known natural satellites (moons)
• Two objects with equal mass are separated by 4 feet. One object is moved to a distance of 8 feet.  How does the force of gravity between them change?
• Two objects with equal mass are separated by 2 astronomical units. One object is moved to a distance of 6 astronomical units. How does the force of gravity between them change?
• Two objects with equal mass are separated by 2 feet. One object is replaced by another with 3 times the mass.  How does the force of gravity between them change?

______________________________________________________________________________________________________________

In other words, for me to provide you with help, you must show me that you have undertaken a good-faith-effort to find the answers yourself, in a timely manner.

______________________________________________________________________________________________________________