Units 1-5 Vocab

Question 1

Measured Earth’s circumference; used length of shadows cast by sun at noon during the summer solstice at 2 different places.

Answer 1

Eratosthenes

Question 2

First to suggest that Earth goes around the Sun (heliocentric model)

Answer 2

Aristarchus

Question 3

Constructed models that could explain retrograde motion. Came up with epicycles to explain retrograde. Assumed the planet rotated about a different point from the earth at a uniform rate. His Earth centered model.

Answer 3

Ptolemy

Question 4

Created a sun-centered model designed to replace the Ptolemaic models (heliocentric model). He had more quantitative models with actual numbers about the planets’ average distances from the sun. Believed planets orbited in circular motion. Said that if earth was in the center, then we would always see stars rise and set.

Answer 4

Copernicus

Question 5

He discovered a supernova after he thought he discovered a star. He challenged the unchanging perfect heavens (proved Aristotle wrong). He dodn’t beeive in the heliocentric model. His model had Earth at center of universe. The Sun, moon, and stars revolve around the Earth, but the 5 naked eye planets revolve around the Sun.

Answer 5

Brahe

Question 6

Thought earth was at the center of the universe, heavens are perfect and unchanging, Earth is subject to decay. Planets, moon, sun, and stars revolve around the Earth in 55 celestial spheres.

Answer 6

Aristotle

Question 7

Hired by Brahe to analyze his planetary data. He proposed elliptical orbits; orbit of the planets are ellipses with the sun at one of the focus. He formulated 3 laws that describe planetary motion.

Answer 7

Kepler

Question 8

The orbit of each planet around the Sun is an ellipse with the Sun at one focus.

Answer 8

Kepler’s First Law

Question 9

As a planet moves around its orbit, it sweeps out equal areas in equal times.

Answer 9

Kepler’s Second Law

Question 10

More distant planets orbit the Sun at slower average speeds, obeying a precise mathematical relationship (P^2=a^2)

Answer 10

Kepler’s Third Law

Question 11

First man to point a telescope at the sky; saw shadows cast by the mountains on the moon (it was a place, not a perfect, heavenly body). Discovered planets have their own systems, like Jupiters 4 moons. First to conclude that sunspots are on the sun. Suggested stars are at a large range of distances, not in the same crystalline sphere. Discovered balls of different mass dropped at the same height, take the same times to fall, independent of their mass.

Answer 11

Galileo

Question 12

Planets usually move eastward through the constellations. Eastward motion is occasionally interrupted by intervals of westward motion. (Apparent Retrograde Motion).

Answer 12

Motion of Planets

Question 13

Took apparent motions very literally; stars, sun, moon, planets fixed on translucent spheres that rotate around fixed Earth.

Answer 13

Geocentric

Question 14

Planets revolve around the Sun at the center of the Universe.

Answer 14

Heliocentric

Question 15

The apparent shifting of an object against the background, due to viewing it from different positions.

Answer 15

Parallax

Question 16

Closet point in an ellipse.

Answer 16

Perihelion

Question 17

Farthest point of ellipse.

Answer 17

Aphelion

Question 18

A type of oval that happens to be the shape of bound orbits.

Answer 18

Ellipse

Question 19

Small circle upon which a planet moves while simultaneously going around a larger circle (the derent) around Earth in the Ptolemaic model of the universe.

Answer 19

Epicycle

Question 20

The large circle upon which a planet follows its circle-upon-circle path around Earth in the (Earth-centered) Ptolemaic model of the Universe.

Answer 20

Deferent

Question 21

Motion that is backward compared to the norm. Ex. Mars during the period of time when it moves westward, rather that the more common eastward, relative to the stars.

Answer 21

Retrograde Motion

Question 22

An object moves at constant velocity unless a force acts to change its speed or direction.

Answer 22

Newton’s First Law

Question 23

Force=mass*acceleration

Answer 23

Newton’s Second Law

Question 24

For every force, there is always an equal and opposite reaction force (along the same line).

Answer 24

Newton’s Third Law

Question 25

The rate at which an object moves (distance/time) Measured in m/s

Answer 25

Speed

Question 26

The combination of speed and direction of motion; it can be stated as a speed in a particular direction. measured in m/s

Answer 26

Velocity

Question 27

The rate at which an object's velocity changes. Measured in m/s^2

Answer 27

Acceleration

Question 28

A great island of stars in space, all held together by gravity and orbiting a common center.

Answer 28

Galaxy

Question 29

The group of about 40 galaxies to which the Milky Way Galaxy belongs.

Answer 29

Local Group

Question 30

The sky as viewed from a particular location on Earth (or another solid object). Objects in the local sky are pinpointed by the coordinates of altitude and direction (or azimuth).

Answer 30

local sky

Question 31

The supercluster of galaxies to which the Local Group belongs.

Answer 31

Local Supercluster

Question 32

The largest known structures in the universe, consisting of many clusters of galaxies, groups of galaxies, and individual galaxies.

Answer 32

Superclusters

Question 33

the sum total of all matter and energy

Answer 33

Universe

Question 34

distance that light can travel in 1 year, which is about 10 trillion kilometers (6 trillion miles).

Answer 34

Light-year (ly)

Question 35

Earth’s average distance from the Sun, which is about 150 million kilometers (93 million miles)

Answer 35

Astronomical Unit (AU)

Question 36

The portion of the entire universe that can be seen from Earth, at least in principle.

Answer 36

Observable Universe

Question 37

The spinning of an object around its axis.

Answer 37

Rotation

Question 38

The orbital motion of one object around another due to gravity.

Answer 38

Orbit

Question 39

The increase in the average distance between galaxies as time progresses.

Answer 39

Expansion

Question 40

Matter that we infer to exist from its gravitational effects but from which we have not detected any light; it apparently dominates the total mass of the universe.

Answer 40

Dark Matter

Question 41

Name sometimes given to energy that could be causing the expansion of the universe to accelerate.

Answer 41

Dark Energy

Question 42

a region of the sky with well-defined borders

Answer 42

Constellation

Question 43

the point directly over Earth’s North Pole.

Answer 43

North celestial pole

Question 44

the point directly over Earth’s South Pole.

Answer 44

South celestial pole

Question 45

is a projection of Earth’s equator into space, makes a complete circle around the celestial sphere.

Answer 45

Celestial equator

Question 46

The path the Sun follows as it appears to circle around the celestial sphere once each year. It crosses the celestial equator at a 23 12 ° angle, because that is the tilt of Earth’s axis.

Answer 46

Ecliptic

Question 47

The boundary between Earth and sky

Answer 47

Horizon

Question 48

The point directly overhead

Answer 48

Zenith

Question 49

An imaginary half circle stretching from the horizon due south, through the zenith, to the horizon due north.

Answer 49

Meridian

Question 50

an object is the angle it appears to span in your field of view.

Answer 50

Angular size

Question 51

between a pair of objects in the sky is the angle that appears to separate them

Answer 51

Angular Distance

Question 52

why do the seasons occur?

Answer 52

the tilt of Earth’s axis causes sunlight to fall differently on Earth at different times of year.

Question 53

the summer solstice in the Northern Hemisphere, occurs around June 21 and is the moment when the Northern Hemisphere is tipped most directly toward the Sun and receives the most direct sunlight.

Answer 53

June Solstice

Question 54

called the winter solstice in the Northern Hemisphere, occurs around December 21 and is the moment when the Northern Hemisphere receives the least direct sunlight.

Answer 54

December Solstice

Question 55

called the spring (or vernal) equinox in the Northern Hemisphere, occurs around March 21 and is the moment when the Northern Hemisphere goes from being tipped slightly away from the Sun to being tipped slightly toward the Sun.

Answer 55

March Equinox

Question 56

called the fall (or autumnal) equinox in the Northern Hemisphere, occurs around September 22 and is the moment when the Northern Hemisphere first starts to be tipped away from the Sun.

Answer 56

September Equinox

Question 57

a gradual wobble that alters the orientation of Earth’s axis in space.

Answer 57

Precession

Question 58

the Moon’s appearance in our sky changes as its position relative to the Sun changes (lasts 29 1/2 days)

Answer 58

Lunar phases

Question 59

Moon rotates on its axis in the same amount of time it takes to orbit Earth

Answer 59

synchronous rotation

Question 60

If the Sun, Earth, and Moon are nearly perfectly aligned, the Moon passes through Earth’s full shadow

Answer 60

Total Lunar Eclipse

Question 61

alignment is somewhat less perfect, only part of the full moon passes through the full shadow

Answer 61

Partial Lunar Eclipse

Question 62

Moon passes only through Earth’s partial shadow (penumbra)

Answer 62

Penumbral Lunar Eclipse

Question 63

occurs when the Moon is in a part of its orbit where it is relatively close to Earth, the Moon’s full shadow can cover a small area of Earth’s surface

Answer 63

Total solar eclipse

Question 64

If the eclipse occurs when the Moon is in a part of its orbit that puts it farther from Earth, the full shadow may not reach Earth’s surface

Answer 64

Annular Solar Eclipse

Question 65

only part of the Sun is blocked from view

Answer 65

Partial Solar Eclipse

Question 66

the apparent shift of position (parallax) of any nearby star (or other object) against the background of distant stars.

Answer 66

Stellar Parallax

Question 67

the apparent surface of the heavens, on which the stars seem to be fixed

Answer 67

Celestial Sphere

Question 68

A star whose complete circle lies above our horizon

Answer 68

Circumpolar star

Question 69

The angular north-south distance between Earth’s equator and a location on Earth’s surface.

Answer 69

Latitude

Question 70

The angular east-west distance between the prime meridian (which passes through Greenwich, England) and a location on Earth’s surface.

Answer 70

Longitude

Question 71

depends on its position relative to the Sun as it orbits Earth

Answer 71

Phase of the moon

Question 72

when Earth’s shadow falls on the Moon

Answer 72

Lunar eclipse

Question 73

when the Moon blocks our view of the Sun

Answer 73

Solar eclipse

Question 74

planetary orbits are not circles but instead are a special type of oval

Answer 74

Ellipse

Question 75

The long axis of the ellipse

Answer 75

major axis

Question 76

each half of the major axis

Answer 76

Semimajor axis

Question 77

a quantity that describes how much an ellipse is stretched out compared to a perfect circle

Answer 77

eccentricity

Question 78

explaining a thing no more assumptions should be made than are necessary.

Answer 78

Occam's razor

Question 79

When a powerful yet simple model makes predictions that survive repeated and varied testing

Answer 79

Theory

Question 80

The circle on Earth with latitude 23.5°N, which marks the northernmost latitude at which the Sun ever passes directly overhead

Answer 80

Tropic of Cancer

Question 81

The circle on Earth with latitude 23.5°S, which marks the southernmost latitude at which the Sun ever passes directly overhead

Answer 81

Tropic of Capricorn

Question 82

mass x velocity

Answer 82

momentum

Question 83

amount of matter in your body.

Answer 83

mass

Question 84

the force that a scale measures when you stand on it; that is, weight depends both on your mass and on the forces (including gravity) acting on your mass.

Answer 84

weight

Question 85

Energy carried by light

Answer 85

radiative energy

Question 86

Stored energy

Answer 86

potential energy

Question 87

Energy of motion

Answer 87

kinetic energy

Question 88

depends on its mass and how far it can fall as a result of gravity

Answer 88

An object’s gravitational potential energy

Question 89

Orbits on which an object travels repeatedly around another object; bound orbits are elliptical in shape.

Answer 89

Bound orbits

Question 90

the distance from one peak to the next (or one trough to the next)

Answer 90

wavelength

Question 91

the number of peaks passing by any point each second.

Answer 91

frequency

Question 92

Light with very long wavelengths (and hence low frequencies)—longer than those of infrared light.

Answer 92

Radio waves

Question 93

The spectrum of a traditional, or incandescent, light bulb (which contains a heated wire filament) is a rainbow of color.

Answer 93

Continuous Spectrum

Question 94

The light that our eyes can see

Answer 94

visible light

Question 95

A thin or low-density cloud of gas emits light only at specific wavelengths that depend on its composition and temperature. The spectrum therefore consists of bright emission lines against a black background

Answer 95

Emission line spectrum

Question 96

If the cloud of gas lies between us and a light bulb (and the cloud is cooler than the light bulb or other light source), we still see most of the continuous spectrum of the light bulb. However, the cloud absorbs light of specific wavelengths, so the spectrum shows dark absorption lines over the background rainbow

Answer 96

Absorption line spectrum

Question 97

summer solstice in the northern hemisphere, occurs around June 21 and is the moment when the NH is tipped most directly toward the sun and receives the most direct sunlight.

Answer 97

June Solstice

Question 98

Winter solstice in the Northern Hemisphere, occurs around December 21st and is the moment when the NH receives the least direct sunlight.

Answer 98

December Solstice

Question 99

Spring equinox in the North Hemisphere, occurs around March 21st and is the moment when the NH goes from being tipped slightly away from the sun to being tipped slightly toward the sun.

Answer 99

March Equinox

Question 100

Autumn equinox in the Northern Hemisphere, occurs around September 21st/22nd and is the moment when the NH first starts to be tipped away from the sun.

Answer 100

September Equinox

Question 101

Phases of the moon starting a New Moon

Answer 101

New moon, waxing crescent, first quarter, waxing gibbous, full moon, waning gibbous, third quarter moon, waning crescent.