ESSC 102 Unit 2

Geocentiric universe

Earth is center of Universe, East to West motion observed

Heliocentic

Sun is the center of the universe

Ptolemy

Created the most seemingly reliable of all the geocentric models using retrograde epicycles, was incorrect

Retrograde Motion

· A planet will move from East to West relative to the stars. Stops, move backwards, then forward again

Stellar Parallax

· Nearer stars should appear to shift in comparison with further stars throughout our orbit year

epicycle

a fictitious, small and circular orbit superimposed on another circular orbit; explained retrograde motion of planets

Copernicus

First to publish heliocentric model, wrong b/c planets were perfect circles

Brahe

designed instruments that improved the heliocentric model

Kepler

Fit the heliocentric model into elliptical paths

Galileo

validated the heliocentric model w/ telescope that helped to solidify the Copernican Revolution

Kepler's 3 laws of planetary motion (in order)

planets move in elliptical orbits around the sun; planet sweeps equal areas and time; planet's orbit time around sun is related to size

P=

time to complete orbit

a=

semimajor axis

Newtons 1st law of motion

inertia

Inertia

· A body at rest, remains at rest and a body in motion remains in motion with a constant speed and in a straight line, unless acted upon by an outside force

Newton's Second Law of Motion

F=ma ( Force=Mass x Acceleration)

Acceleration

change in velocity

Universal gravitaiton

· Mass (M) increases the force of gravity while distance ® decreases it

Newton's Third Law of Motion

For every action there is an equal and opposite reaction

surface gravity

the acceleration caused by gravity at the surface of a planet or other body

Escape velocity

The velocity an object must reach to fly beyond a planet's or moon's gravitational pull.

Escape velocity determines

celestial body's atmosphere

Nebular Theory

the theory that the solar and stellar systems were developed from a primeval nebula.

evidence supporting nebular theory

orbital motion of planets and age of planetary accretion

Conservation of Energy

a principle stating that energy cannot be created or destroyed, but can be altered from one form to another.

Conservation of Energy effect on Nebula

Solar Nebula heated up as it collapsed, creating star (Sun)

Conservation of angular momentum effect on the Nebula

rotation speed of the cloud from which our solar system formed must have increased as the cloud contracted / collapsed inward

angular momentum formula

mass x velocity x radius

Nebula velocity increase

enables collisions between particles that build planet

Pink Cats Bring Kinda Grumpy Noises

Ptolemy, Copernicus, Brahe, Kepler, Galileo, Newton

F

Force

M

Mass

A

Acceleration