Sun-centred Universe Flashcards
What changed from Ptolemy’s model to Copenicus’?
The sun was at the centre.
What did Tycho Brahe understand?
That a exploding star was not a comet.
What is different in Tycho’s model compared to Ptolemy?
Mars is closer to the Earth than the Sun. The sun revolves around the Earth and all the planets revolve around the Sun.
What did kepler start considering when trying to make Tycho’s model fit?
Started considering oval orbits with planets travelling not at a constant speed.
What is an ellipse?
A closed plane curve generated in such a way that the sum of its distances from the two fixed foci is constant.
What is eccentricity?
The distance between the two focal points divided by the major axis.
What is Kepler’s first law?
Each planet travels in an ellipse around the Sun. The sun is at a focus of the ellipse.
What is Kepler’s second law?
A planet moves at a changing speed around its orbit. As it moves, the area it sweeps out in a space in a given time is constant.
What is Kepler’s third law?
P^2=a^3
