Clcs Vocab Quiz 5

Front 1

axial obliquity

Back 1

angle between rotational axis and line perpendicular to orbital plane

Front 2

celestial sphere

Back 2

projected sphere of arbitrary radius with Earth at center.

Front 3

celestial equator

Back 3

projected circle along plane of terrestrial equator intersecting celestial sphere

Front 4

Counter-Earth

Back 4

hypothetical planet on opposite orbital track to that of Earth

Front 5

ecliptic

Back 5

apparent path of Sun on celestial sphere, relative to celestial equator.

Front 6

equinox

Back 6

intersection of ecliptic with celestial equator, in spring (vernal equinox) and autumn (autumnal equinox), marking day and night of equal lengths.

Front 7

occultation

Back 7

concealment of smaller by larger celestial body passing between former body and observer

Front 8

parapegma

Back 8

wood or stone peg-board calendar with astronomical observations

Front 9

planêtês

Back 9

planet, "wandering" celestial body

Front 10

solstice

Back 10

highest (summer solstice) and lowest (winter solstice) point reached by Sun along ecliptic, marking longest and shortest days.

Front 11

Spindle of Necessity

Back 11

Platonic model of concentric celestial spheres

Front 12

zodiac

Back 12

twelve 30-degree divisions of plane roughly 8 degrees above and below plane of ecliptic, bearing principal constellati0ns.

Front 13

aither

Back 13

5th element, characterized by perpetual circular movement

Front 14

dynamis

Back 14

immanent potential

Front 15

efficient cause

Back 15

agent or agency responsible for change

Front 16

energeia

Back 16

actualization of potential

Front 17

formal cause

Back 17

shape or appearance into which matter is molded

Front 18

hippopede

Back 18

"horse-fetter," figure-8 movement illustrating retrogression

Front 19

material cause

Back 19

matter

Front 20

retrogression

Back 20

apparent temporary reverse motion of planet

Front 21

telic (final) cause

Back 21

purpose for which change occurs

Front 22

telos

Back 22

aim, end, destination

Front 23

Unmoved Mover

Back 23

God as souce of all movement

Front 24

armillary sphere

Back 24

three-dimensional model of geocentric universe

Front 25

deferent

Back 25

circular orbit on which center of smaller epicycle moves

Front 26

eccentric

Back 26

center of an orbit offset from observational point

Front 27

epicycle

Back 27

circular orbit centered on point moving along larger orbital circle (deferent)

Front 28

gnomon

Back 28

vertical marker in skaphê that projects sun's shadow

Front 29

heliocentrism

Back 29

theory that Sun is center of universe

Front 30

skaphê

Back 30

bowl-shaped instrument for measuring angle of Sun's shadow

Front 31

Antikythera mechanism

Back 31

1st century BCE mechanism displaying positions of stars, Sun, Moon and planets

Front 32

dioptra

Back 32

sighting instrument for measuring angles of celestial bodies

Front 33

parallax

Back 33

apparent shift in position of object caused by motion of observer

Front 34

precession

Back 34

gradual retrograde movement of equinoxes due to gravitational pulls Earth's rotational axis

Front 35

Almagest

Back 35

major work on astronomy ascribed to Ptolemy

Front 36

epi-epicycle

Back 36

orbital path centered on point that is itself in orbit around a point on a deferent

Front 37

equant

Back 37

point opposite and equidistant from Earth in an eccentric model

Front 38

Tetrabiblos

Back 38

major work on astrology ascribed to Ptolemy