Chapter 3 : The Planet Puzzle
One reason that the Copernican System failed to fit Tycho's observations was that
it used circular orbits instead of ellipses.
By making extensive observations of planetary motion, Tycho Brahe
provided accurate data for the first time.
The statement that the orbit of each planet is an ellipse with the Sun at one focus is due to
Kepler.
Tycho Brahe's careful observations of the planets agreed, to within observational error, with
None of these systems.
Which of these was the Solar System model that assumed the Earth is fixed and the Sun, Moon, and planets all move on epicycles that, in turn move on circular orbits around the Earth?
Ptolemaic model.
Which of Kepler's Laws governs how a particular planet speeds up and slows down?
The Equal Area Law.
Which of the following astronomers is regarded as an early example of government-supported Big Science.
Tycho Brahe.
Aristarchus of Samos is known for a number of things. One of them was
a model in which the Earth rotates on its axis and revolves around the Sun.
In comparison to the Copernican Theory, the Ptolemaic Theory made predictions that were of
about the same accuracy.
Copernicus said that the rotation of the Earth on its axis caused the
daily motions in the heavens.
As the two foci of an ellipse are moved apart, the shape of the ellipse becomes
more like a line between the foci.
When compared to planets that are closer to the sun, planets that are farther from the sun
move slower on the average.
The ancient Greeks argued that the Earth cannot be moving because such a motion would cause apparent shifts in the positions of stars. This argument was wrong because
the stars are so far away that the shifts due to the Earth's motion are extremely small.
Retrograde Motion refers to the
westward motion of the planets relative to the stars.