Lecture 2
Geocentric vs heliocentric solar system
Thursday July 3, 2008
The powerpoint presentation went through some of the accomplishments of Greek astronomy, then discussed the reasoning behind the
geocentric and then heliocentric models of the solar system
(available on Angel). We looked at
these useful animations:
geocentric and heliocentric models,
retrograde motion, and
parallax. Next lecture
will cover Kepler's and Newton's laws.
Concepts:
- Our place in universe: Earth not at center.
- Phases: Planets, like moon, shine by reflected sunlight; can see phases.
- Geocentric model: Complex system of epicycles on deferents to explain planetary motions.
- Heliocentric model: Elegant model with all planets orbiting sun, supported by observations.
- Parallax: Change in apparent position of object against background as viewed from different perspectives.
Vocabulary:
- Geocentric: Earth at center of solar system.
- Heliocentric: Sun at center of solar system, all planets orbit sun.
- Retrograde motion: Apparent looping back of planet along its projected position on the sky.
- Parsec: Distance at which parallax of object is 1 arc-second (about 3.26 light years).
Activity:
None
Random link:
Excerpt from Science Daily article titled "Phoenix Mars Lander Returns Treasure Trove For Science"
"We are awash in chemistry data," said Michael Hecht of NASA's Jet Propulsion Laboratory, lead scientist for the Microscopy, Electrochemistry and Conductivity Analyzer, or MECA, instrument on Phoenix. "We're trying to understand what is the chemistry of wet soil on Mars, what's dissolved in it, how acidic or alkaline it is. With the results we received from Phoenix yesterday, we could begin to tell what aspects of the soil might support life."
"This is the first wet-chemical analysis ever done on Mars or any planet, other than Earth," said Phoenix co-investigator Sam Kounaves of Tufts University, science lead for the wet chemistry investigation.
Updated July 3, 2008