# Astronomy Section 1

### 23 terms by caitlynchausow

#### Study  only

Flashcards Flashcards

Scatter Scatter

Scatter Scatter

## Create a new folder

### Parallax

the apparent motion of a relatively close object with respect to a more distant background as the location of the observer changes

### Geocentric Model

earth stationary at the center of the universe

### Heliocentric Model

sun stationary at the center of the universe

### Aristotle

first to suggest the geocentric model

### Ptolemy

noticed that planets speed-up, slow-down, and even reverse direction of motion (retrograde motion). Model contained epicycles.

### Deferent

a large circle encircling Earth, on which an epicycle moves

### Epicycle

each plant rides on a small _____ whose center in turn rides on a larger circle called the deferent

### Supported the Geocentric Model

stars don't seem to show any parallax

### Supported the Geocentric Model

we don't feel as though the Earth moves

### Supported the Geocentric Model

objects fall toward Earth, not the sun

### Copernican

reintroduced the Heliocentric model

### Copernican Model

model accounted for retrograde motion. Lacked uniform circular motion (same speed all along the circle)

### Tycho Brahe

made own instruments to observe the universe. Believed that the sun and moon orbited the Earth and then all the other planets and stars orbited around the sun

### Kepler

said that orbits are ellipses not circles

### Kepler's 1st Law

planetary orbits are ellipses, sun at one focus

closest to sun

### Aphellon

farthest from sun

### Kepler's 2nd Law

draw imaginary line from planet to sun. sweeps over equal area in equal time. Distance between the planet and the sun changes as the planet orbits the sun.

### Kepler's 3rd Law

planet's orbital period squared is proportional to cube of its average distance from sun

### Galileo

confirmed Copernicans ideas with three major results from use of telescope

### Galileo's Finding that Contradicts Ptolemy Model

phases of Venus: crescent when close to Earth, gibbous when furthest away. Concluded Venus revolves around the sun.

### Aristarchu

1st suggested heliocentric model

### Known Planets

Mercury, Venus, Mars, Jupiter, Saturn (sun and moon)

Example:

## Press Ctrl-0 to reset your zoom

### Please upgrade Flash or install Chrometo use Voice Recording.

For more help, see our troubleshooting page.

Create Set