Lecture 5 : the grocentric vs heliocentric model Flashcards
1) distinguish between the geocentric and heliocentric models 2) differentiate between direct adn retrogarde motion 3)sidereal period, synodic month, opposition and conjuction 4) Keplers Laws ofplanetry motion
The Greek’s thought the Universe was made of 4 —-1—- (earth, water, air and fire)
* The celestial sphere was —2—, made with —3— to let the fire behind pass through in the form of stars.
* They believed in the —-4—- model
✓ —-5—–of the Moon
✓ E——–(5)
1)elements
2)real
3)holes
4)geocentric
5) Phases
6)Eclipses
Issues with geocentric model
The Sun, Moon and planets move —-1—- with respect to the stars
(direct motion). Note: this is regardless of their rising in the —2— and setting in the —3— .
* However, some planets seem to have some kind of “—-4—- motion” where they move —-5—– for a few days.
1) eastward
2) east
3) west
4) retrograde
5) westward
The Ptolemaic System
Each planet moves in small circles called —1—- , which at the same time moves around a larger circle called —2—-, —3—- at Earth.
The problem with this system is that it treats each planet —4— .
* There is no model for which an underlying —-5—- ——— can be applied to all planets
1) epicycles
2) deferent
3) centered
4) independently
5) physical principle
Synodic period: time that elapses between two —-1—- identical —-2—– as seen from Earth.
Sidereal period: true —3— period of a planet (time it takes the planet to complete one full orbit around the Sun)
1)successive
2)configurations
3)orbital
More evidences of Earth’s rotation
around its axis: p—-1—-
Closer object to –2— : bigger parallax.
Very —3— stars: almost no parallax
1)parallax
2)earth
3)distant
Each planet’s path around the Sun is an —-1——,
with the Sun at one —-2— of the ellipse
1) ellipse
2) centre
A planet moves along its elliptical path with a
—1— that —-2— in such a way that a line
from the planet to the Sun sweeps out —-3—-
areas in equal intervals of —-4—
1)speed
2)changes
3)equal
4)time
The –1— of a planet’s (or minor body) —-2—
—3— is —-4— to the —5— of its semi-
major axis
1)square
2)orbital
3)period
4)proportional
5)cube