Ptolemaic Model
What shape did Ptolemy believe the planets' orbits to be? Why?
Circular- the circle was considered the most perfect shape
Was Copernicus' model geocentric or heliocentric?
Heliocentric
How many laws of planetary motion did Kepler develop?
3
Isaac Newton formulated the first quantitative law of gravity- what is it called?
The law of universal gravitation
What is a geocentric model?
A model of planetary motion that states that all of the heavenly bodies are orbiting around a stationary earth (earth-centered model)
How many spheres of planets did Ptolemy account for in his model?
7 planets (moon, mercury, venus, sun, mars, jupiter, and saturn)
What shape did Copernicus believe the planets' orbits to be?
Circular
Name one of Galileo's discoveries that we covered in class
He improved the telescope, observed the craters on the moon, discovered 4 of the moons around Jupiter
Describe Newton's law of universal gravitation in one sentence (or less)
every object with mass in the universe pulls on every other object with mass in the universe
What is a heliocentric model?
A model of planetary motion that states the heavenly bodies are orbiting the sun (sun-centered model)
What is the firmament in the Ptolemaic model?
A fixed layer of stars that rotates each day
Who took over Tycho's position as imperial mathematician after he died?
Johannes Kepler
What is Kepler's first law of planetary motion?
Each of the planetary orbits is an ellipse, with the sun as one focus
In this chapter we looked at Newton's law of universal gravitation- what else is he known for?
What did Aristotle believe about the heavenly bodies?
That they were eternal and perfect, they orbit the earth in perfect circles
What is the Primum Mobile in the Ptolemaic model?
Latin for "prime mover", the sphere set into motion by God or the gods
What two significant astronomical events did Tycho witness?
A conjunction (between Jupiter and Saturn) and a Nova (a new star being born)
Why was Galileo's discovery of 4 of Jupiter's moons significant?
It showed that there were more than 7 heavenly bodies, further breaking down evidence in favor of the Ptolemaic model
How was Einstein's hypothesis about gravity affecting objects without mass confirmed?
A team of scientists photographed stars during a solar eclipse and measure the difference between the eclipse picture positions and their positions when the sun was further away
What is an epicycle?
A small circle or circular orbit that itself moves along a much larger circular orbit
How did Ptolemy explain the retrograde motion of planets?
Epicycles
What was the significance of the conjunction that Tycho witnessed?
He predicted when it would be according to Copernicus' model, but he was off by a few days- this indicated that Copernicus' model was not fully accurate, something was still missing
Why was Galileo put on trial?
He believed that math could prove the truth of nature, rather than treating theories as models of nature
What is the biggest difference between Einstein's theory for gravity and Newton's?
Einstein theorized that even objects without mass (such as lightrays) are affected by gravity
What are some of the reasons the church supported a geocentric model of planetary motion for so long?
Cited certain bible verses that when read literally make it sound like the earth is stationary