Quiz 2 on Kepler, Tycho and what not Flashcards
What was Tycho’s model of the solar system?
Tycho believed in a geocentric theory that didn’t follow the hypothesis of Copernicus, because he found it to be inaccurate. Tycho was a Geocentric man. However, Tycho also rejected the ptolemaic model because he found many inconsistencies in it. Tycho eventually made his own model that was very popular when released, but was replaced with the Copernican model within the century.
What caused tycho to make his own model of the universe?
When observing Jupiter and Saturn almost perfectly eclipsing each other, Tycho found that the old Alfonsine tables based on the Ptolemaic model were a full month in error in their prediction of that event, and the new Prutenic Tables, based on the Copernican model were in error by several days.
Who did Tycho Brahe hire to assist with his astronomical research?
Johannes Kepler
What did Kepler discover about the movement and speed of planets in the solar system?
Kepler discovered that planets don’t move in circles, but rather ellipses, and also that planets complete their orbits at different speeds.
What is the geometry of an ellipse made out of?
It is made of the semimajor axis, a, which is half of the longest diameter of the ellipse. It is also made of the eccentricity, e, which is half the distance between the foci divided by the semimajor axis. The eccentricity of an ellipse tells you its shape; if e is nearly equal to oe, the ellipse is very elongated. If e is close to zero, the ellipse is more circular. All circles are ellipse, but not ellipses are circles.
What is Kepler’s First law?
Kepler’s first law says that the orbits of the planets around the Sun are ellipses with the Sun at one focus.
What is Kepler’s Second law?
Kepler’s second law says that an imaginary line drawn from the planet to the Sun always sweeps over equal areas in equal intervals of time. This means that when the planet is closer to the Sun and the line connecting it to the Sun is shorter, the planet must move more rapidly so that the line sweeps over when the planet is farther from the Sun.
What is Kepler’s Third law?
Kepler’s third law relates a planet’s orbital period to its average distance from the Sun. The orbital period, P, is the time a planet takes to travel around the Sun once. The average distance of a planet from the Sun around its elliptical path turns out simply to equal the semimajor axis of its orbit, a. Kepler’s third law says that a planet’s orbital period squared is proportional to the semi-major axis of its orbit cubed. Measuring P in years and a in astronomical units.
Example: What is the orbital period of Jupiter?
Solution: Jupiter’s average distance from the Sun is 5.20 astronomical units (AU). That value cubed is about 141, so the period must be the square root of 141, which equals 11.9 years.
What was The Rudolphine tables?
Kepler’s masterpiece that could predict the positions of the planets 10 to 100 times more accurately than previous tables. Kepler’s tables were the precise model of planetary motion that Copernicus had sought but failed to find because he could not give up the idea of perfectly circular motions. The accuracy of the Rudolphine Tables was strong evidence that both Kepler’s laws of planetary motion and the Copernican hypothesis for the place of Earth were correct. Copernicus would have been pleased.
When was Johannes Kepler born, and when did he die?
1571-1630
When was Tycho Brahe born, and when did he die?
1546-1601
What are the two misconceptions about Galileo?
He invented the telescope, he was condemned by the Inquisition for believing the Earth moves around the Sun.
When was Galileo Galilei born and when did he die?
1564-1642
What did Galileo do in regards to the telescope that was never done?
Although Galileo wasn’t the first person to look at the sky through a telescope, he was the first person to to write down what he discovered and apply telescopic observations to the theoretical problem of the day: the place of Earth in the Universe.
What did Galileo discover when he looked charted what he saw through telescopes?
- He saw the moon was not perfect. It had mountains and valleys on its surface, and Galileo even used some of the mountains’ shadows to calculate their height. This debunked Aristotle’s thought that the moon was perfect and the man in the moon was a reflection of earth. The moon actually has very similar imperfections as Earth.
- Galileo discovered that the Milky Way was made up of countless stars invisible to the naked eye.
- Galileo’s telescope revealed four new “planets” circling Jupiter, objects know today as the Galilean moons of Jupiter. The moons of Jupiter were strong evidence for the Copernican model and offered a solution to the heliocentric model; An explanation of how the earth could hang onto the moon if it orbited the Sun. Also how something could revolve around something other than the Earth in general.
- When Observing the Sun, Galileo observed that it had many different Sun spots implying that the Sun, much like the moon, was not perfect as believed previously. He also discovered that the Sun is a sphere and rotated on its axis.
- When Galileo observed Venus, he saw that it was going through phases such like those of the Moon in the Ptolemaic model. Venus moved around an epicycle centered on a line between Earth and the Sun. that means it would always be seen as a crescent. Galileo however saw that Venus went through a complete set of phases which proved that it did indeed revolve all the way around the Sun. This was the strongest bit of evidence to support the Copernican model.
