Astronomy Test 1

Front 1

A large glowing ball of gas that generates heat and light through nuclear fusion.

Back 1

star

Front 2

A moderately large object that orbits a star; it shines by reflected light and its composition may be rocky, icy, or gaseous.

Back 2

planet

Front 3

An object that orbits a planet.

Back 3

moon (or satellite)

Front 4

A relatively small and rocky object that orbits a star.

Back 4

asteroid

Front 5

A relatively small and icy object that orbits a star.

Back 5

comet

Front 6

A star and all the material that orbits it, including its planets and moons.

Back 6

solar system (star system)

Front 7

An interstellar cloud of gas and/or dust.

Back 7

nebula

Front 8

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

Back 8

galaxy

Front 9

The sum total of all matter and energy; that is, everything within and between all galaxies.

Back 9

universe

Front 10

A transparent globe around the Earth where the Sun, Moon, and stars appear.

Back 10

Celestial Sphere

Front 11

Position north or south of the equator.

Back 11

latitude

Front 12

Position east or west of the prime meridian.

Back 12

longitude

Front 13

Projections of the Earth's north and south poles onto the celestial sphere.

Back 13

Celestial poles

Front 14

Projection of the Earth's equator onto the celestial sphere.

Back 14

Celestial equator

Front 15

Point directly overhead.

Back 15

zenith

Front 16

Marks the intersection of the Earth an sky.

Back 16

horizon

Front 17

Angular height above the horizon.

Back 17

altitude

Front 18

Line through the zenith, connecting North and South on horizon.

Back 18

meridian

Front 19

Why do stars rise and set?

Back 19

Earth rotates west to east on its axis, so stars appear to circle from east to west about the celestial poles.

Front 20

Stars near a celestial pole that never "set".

Back 20

circumpolar stars

Front 21

Why don't we see the same constellations throughout the year?

Back 21

The constellations we see vary with latitude and the time of year because the Earth orbits the Sun.

Front 22

The path the sun seems to take eastward along the celestial sphere.

Back 22

ecliptic

Front 23

Why do we see different stars at night throughout the year?

Back 23

The night sky is opposite the Sun and as we go around the Sun, the direction of "night" changes.

Front 24

What causes the seasons?

Back 24

The tilt of the Earth's rotation axis. Sunlight is either concentrated or spread out along each hemisphere at different times of the year.

Front 25

The highest path of the Sun; it rises and sets at the most extreme north of due east.

Back 25

summer solstice

Front 26

The lowest path of the Sun; it rises and sets at the most extreme south of due east.

Back 26

winter solstice

Front 27

When the ecliptic crosses the celestial equator; Sun rises precisely due east and sets precisely due west.

Back 27

equinoxes

Front 28

The "wobble" of the Earth's axis.

Back 28

precession

Front 29

Why do we only see one face of the Moon?

Back 29

The Moon has a synchronous orbit and its rotation period equals its orbital period, so we always see the same face of the Moon.

Front 30

What causes eclipses?

Back 30

When the Earth or Moon passes through the others shadow.

Front 31

How do lunar eclipses occur?

Back 31

They occur when the Moon passes into the Earth's shadow; it can only happen at a FULL MOON and can be penumbral, partial, or total.

Front 32

How does a solar eclipse occur?

Back 32

They occur when the Moon's shadow falls directly on the Earth; it can only happen at a NEW MOON and can only be totally visible on part of the Earth.

Front 33

When the moon only partially blocks the Sun.

Back 33

partial eclipse

Front 34

When the Moon completely blocks the Sun.

Back 34

total eclipse

Front 35

When the moon is too small in the sky to completely block the sun.

Back 35

annular eclipse

Front 36

Why don't we have an eclipse at every new and full moon?

Back 36

The Moon's orbit is tilted 5 degrees to the ecliptic plane and the Moon must be close to the ecliptic for an eclipse to occur.

Front 37

What are the two conditions that need to be met for there to be an eclipse?

Back 37

1) It must be a full moo (lunar) or new moon (solar).
2) The Moon must be at or near one of the two points in its orbit ("nodes") where it crosses the ecliptic.

Front 38

Explain retrograde motion.

Back 38

Apparent retrograde motion occurs when we "lap" another planet (or it laps us). The planets do not actually move backwards.

Front 39

Why do we see moon phases?

Back 39

We see moon phases because we observe some combination of the day and night sides of the moon.

Front 40

What did ancient civilizations achieve in astronomy?

Back 40

Ancient civilizations kept track of time and seasons, monitored lunar cycles, planets and stars, predicted eclipses, and aided in navigation.

Front 41

How did the Greeks explain planetary motion?

Back 41

They made models placing the Earth at the center of the universe and claimed that the Heavens must be "perfect" and so objects orbited the Earth in perfect spheres or in perfect circles.

Front 42

The apparent change in the location of an object due to the difference in location of the observer.

Back 42

parallax

Front 43

What is Kepler's First Law of Planetary Motion?

Back 43

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

Front 44

What is Kepler's Second Law of Planetary Motion?

Back 44

As a planet moves around its orbit, it sweeps out equal areas in equal times. A planet travels faster when it is nearer to the Sun and slower when it is farther from the Sun.

Front 45

What is Kepler's Third Law of Planetary Motion?

Back 45

More distant planets orbit the Sun at slower average speeds, obeying the relationship p^2 = a^3.

Front 46

What did Galileo see through his telescope?

Back 46

Sunspots on the Sun, mountains and valleys on the Moon, four moons orbiting Jupiter, and the phases of Venus.

Front 47

What is the First Hallmark of Science?

Back 47

Modern science seeks explanations for observed phenomena that rely solely on natural causes. A scientific model cannot include supernatural elements.

Front 48

What is the Second Hallmark of Science?

Back 48

Science progresses through the creation and testing of models of nature that explain the observations as simply as possible.

Front 49

What is the Third Hallmark of Science?

Back 49

A scientific model must make testable predictions about natural phenomena that would force us to revise or abandon the model if the predictions do not agree with observations.

Front 50

What must a scientific theory do?

Back 50

It must explain a wide variety of observations with a few simple principles, must be supported by a large, compelling body of evidence, and must not have failed any crucial tests of validity.

Front 51

A tentative explanation for an observation that can be tested by further investigation.

Back 51

hypothesis

Front 52

An observed mathematical relationship seen in nature, though we may not have an explanation for it.

Back 52

law

Front 53

An explanation that accounts for existing observations and predicts new ones.

Back 53

model

Front 54

A model that is supported by a large body of evidence and has not failed any tests of its predictions.

Back 54

theory

Front 55

The rate at which an object moves.

Back 55

speed

Front 56

What is the speed equation?

Back 56

speed = distance / time

Front 57

Speed and direction.

Back 57

velocity

Front 58

Any change in velocity.

Back 58

acceleration

Front 59

What is the momentum equation?

Back 59

momentum = mass x velocity

Front 60

Rotational momentum of a spinning or orbiting object.

Back 60

angular momentum

Front 61

The amount of matter in an object.

Back 61

mass

Front 62

The force that acts upon an object.

Back 62

weight

Front 63

What is Newton's First Law of Motion (Inertia)?

Back 63

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

Front 64

What is Newton's Second Law of Motion?

Back 64

Force = mass x acceleration

F = m x a

Front 65

What is Newton's Third Law of Motion?

Back 65

For every force, there is always an equal and opposite reaction force.

Front 66

What is the Universal Law of Gravitation?

Back 66

Every mass attracts other mass. Attraction is directly proportional to the product of their masses. Attraction is inversely proportional to the square of the distance between their centers.

Front 67

What is Newton's Law of Gravity?

Back 67

Gravity depends on masses of two objects divided by their distance, squared.

Front 68

What is Newton's version of Kepler's First Law?

Back 68

Orbits are ellipses, parabolas, and hyperbolas.

Front 69

What is Newton's version of Kepler's Second Law?

Back 69

An orbit's angular momentum is conserved.

Front 70

What is Newton's version of Kepler's Third Law?

Back 70

Orbital period depends on distance and the masses of the orbiting bodies.

Front 71

What is conservation of momentum?

Back 71

The total momentum of interacting objects cannot change unless an external force is acting on them. Interacting objects exchange momentum through equal and opposite forces.

Front 72

The collective kinetic energy of many particles. Depends on both temperature and density.

Back 72

thermal energy

Front 73

The average kinetic energy of the many particles in a substance.

Back 73

temperature

Front 74

How are tides caused?

Back 74

Tides are caused by the difference in gravitational pull across the Earth by the Moon.

Front 75

What is true of falling objects on a planet?

Back 75

Acceleration of gravity on a planet is the same for all falling objects, regardless of mass.