Observing the Solar System

1
Observing the Solar System

• Section 20.1

2
Early Observations

• Greek Observations
• Saw star patterns in the sky travel together
• (Constellations)

3
(No Transcript)
4
Early Observations

• Some stars seemed to wander (planets)
• They were later named by the Romans
• (Mercury, Venus, Mars, Jupiter, Saturn)

5
Early Observations

• Most Greek astronomers believed that Earth was in
  the center of a celestial sphere. (geocentric
  system)

6
Early Observations

• Claudius Ptolemy
• Earth in center
• Planets move on small
• circle that move on
• bigger circles
• Widely accepted for
• 1500 years

7
Early Observations

• Nicholas Copernicus
• Believed in a sun centered system (Heliocentric)
• Said the planets moved around the sun in circles
  in 1543

Mikolaj Kopernik
8
Early Observations

• Nicholas Copernicus
• Was banned by the Catholic church
• Galileo
• Used the telescope to support him (Venus phases,
  Jupiters moons)
• Was placed under house arrest

Mikolaj Kopernik
Galileo
9
Early Observations

• Tycho Brahe
• Made accurate observation for over 20 years

10
Early Observations

• Johannes Kepler
• Analyzed Brahes observations and found that the
  path of the orbits were ellipses
• Keplers 1st Law

11
Early Observations

• Johannes Kepler
• He found that the speed of orbiting planets is
  constantly changing
• Keplers 2nd Law

12
Early Observations

• Johannes Kepler
• When he compared planets, he found a relationship
  between how far from the sun they were and the
  time to make one orbit
• Keplers 3rd Law

13
Early Observations

• Today we know of 8 planets (MVEMJSUN) their
  moons, and smaller objects that revolve around
  the sun

14
What about Pluto?

• According to the new definition, a full-fledged
  planet is an object that orbits the sun and is
  large enough to have become round due to the
  force of its own gravity. In addition, a planet
  has to dominate the neighborhood around its
  orbit.
• Pluto does not dominate its neighborhood
• Charon is half it size
• It does not sweep up its neighborhood, there
  is
• much debris in its orbit