Epicycles and Planetary Motion
The "solution" to these problems came in the form of a mad, but clever proposal: planets were
attached, not to the concentric spheres themselves, but to circles attached to the concentric
spheres, as illustrated in the adjac
. There are differences between Newton's theory of gravitation and the theory of gravitation
implied by the General Theory of Relativity. They make essentially identical predictions as long
as the strength of the gravitational field is weak, which is our
Astronomers use 2 main systems.
1. The Horizon System:
Altitude degrees (0 90) above the horizon.
Azimuth degrees (0 360) around the
horizon from the north point.
This coordinate system serves to answer the question where
is a particula
General scales of the Universe: the astronomical unit, solar system distances and
sizes, and the light year.
The Horizon system of coordinates (Altitude/Azimuth). Advantages and
disadvantages of such a Local Coordinate system. The concept of the L
Finding the Distances to the
First, best technique = surveying (or
Classical Greeks attempted this
observation, but failed.
- Stars are too far!
Tycho Brahe thought he detected it with
naked eye observations, b
Brahe's Data and Kepler
Kepler and Brahe did not get along well. Brahe apparently mistrusted Kepler, fearing that his
bright young assistant might eclipse him as the premiere astonomer of his day. He therefore let
Kepler see only part of his voluminous da