Astronomy Quiz 2

Front 1

total solar eclipse

Back 1

a solar eclipse during which the Sun becomes fully blocked by the disk of the Moon

Front 2

focus (of an ellipse)

Back 2

one of two special points within an ellipse that lie along the major axis; when one object orbits a second object, the second object lies at one focus of the orbit

Front 3

arcseconds

Back 3

one arcsecond is 1/60 of an arcminute

Front 4

analemma

Back 4

the figure eight path traced by the Sun over the course of a year when viewed at the same place and the same time each day; represents the discrepancies between apparent and mean solar time

Front 5

north celestial pole

Back 5

the point on the celestial sphere directly above the Earth's North Pole

Front 6

science

Back 6

the search for knowledge that can be used to explain or predict natural phenomena in a way that can be confirmed by rigorous observations or experiments

Front 7

constellation

Back 7

a region of the sky

Front 8

scientific theory

Back 8

a model of some aspect of nature that has been rigorously tested and has passed all tests to date

Front 9

pseudoscience

Back 9

something that purports to be science or may appear to be scientific but does not adhere to the testing and verification requirements of the scientific method

Front 10

lunar phase

Back 10

describes the appearance of the Moon as seen from Earth

Front 11

longitude

Back 11

the angular east-west distance between the prime meridian and a location on the Earth's surface

Front 12

annular solar eclipse

Back 12

a solar eclipse during which the Moon is directly in front of the Sun but its angular size is not large enough to fully block the Sun; thus a ring (or annulus) of sunlight is still visible around the Moon's disk

Front 13

meridian

Back 13

a half-circle extending from your horizon due south, through your zenith, to your horizon due north

Front 14

eclipse seasons

Back 14

periods during which lunar and solar eclipses can occur because the modes of the Moon's orbit are nearly aligned with the Earth and Sun

Front 15

antimatter

Back 15

refers to any particle with the same mass as a particle of ordinary matter but whose other basic properties are precisely opposite

Front 16

DNA

Back 16

the molecule that represents the genetic material of life on Earth

Front 17

precession

Back 17

the gradual wobble of the axis of a rotating object around a vertical line

Front 18

aphelion

Back 18

the point at which an object orbiting the Sun is farthest from the Sun

Front 19

altitude (above horizon)

Back 19

the angular distance between the horizon and an object in the sky

Front 20

Arctic Circle

Back 20

the circle on the Earth with latitude 66.5 degrees N

Front 21

winter solstice

Back 21

the point on the celestial sphere where the ecliptic is farthest south of the celestial equator; the moment in time when the Sun appears at that point each year (December 21)

Front 22

Ptolemaic model

Back 22

the geocentric model of the universe developed by Ptolemy in about 150 AD

Front 23

axis tilt

Back 23

the amount by which a planet's axis is tilted with respect to a line perpendicular to the ecliptic plane

Front 24

Copernican revolution

Back 24

the dramatic change that occurred when we learned that Earth is a planet orbiting the Sun rather than the center of the universe

Front 25

carbon dioxide cycle

Back 25

the process that cycles carbon dioxide between the Earth's atmosphere and surface rocks

Front 26

arcminutes

Back 26

one arcminute is 1/60 of a degree

Front 27

geocentric model

Back 27

any of the ancient Greek models that were used to predict planetary positions under the assumption that Earth lay in the center of the universe

Front 28

paradigm

Back 28

refers to general patterns of thought that tend to shape scientific beliefs during a particular time period

Front 29

altitude (above horizon)

Back 29

the angular distance between the horizon and an object in the sky

Front 30

Arctic Circle

Back 30

the circle on the Earth with latitude 66.5 degrees N

Front 31

winter solstice

Back 31

the point on the celestial sphere where the ecliptic is farthest south of the celestial equator; the moment in time when the Sun appears at that point each year (December 21)

Front 32

Ptolemaic model

Back 32

the geocentric model of the universe developed by Ptolemy in about 150 AD

Front 33

axis tilt

Back 33

the amount by which a planet's axis is tilted with respect to a line perpendicular to the ecliptic plane

Front 34

Copernican revolution

Back 34

the dramatic change that occurred when we learned that Earth is a planet orbiting the Sun rather than the center of the universe

Front 35

carbon dioxide cycle

Back 35

the process that cycles carbon dioxide between the Earth's atmosphere and surface rocks

Front 36

arcminutes

Back 36

one arcminute is 1/60 of a degree

Front 37

geocentric model

Back 37

any of the ancient Greek models that were used to predict planetary positions under the assumption that Earth lay in the center of the universe

Front 38

paradigm

Back 38

refers to general patterns of thought that tend to shape scientific beliefs during a particular time period

Front 39

horizon

Back 39

a boundary that divides what we can see from what we cannot see

Front 40

ecliptic

Back 40

the Sun's apparent annual path among the constellations

Front 41

eccentricity

Back 41

a measure of how much an ellipse deviates from a perfect circle; the center-to-focus distance divided by the length of the semimajor axis

Front 42

spring equinox

Back 42

the point in Pisces on the celestial sphere where the ecliptic crosses the celestial equator; the moment in time when the Sun appears at that point each year (March 21)

Front 43

eclipse

Back 43

occurs when one astronomical object casts a shadow on another or crosses our line of sight to the other object

Front 44

perihelion

Back 44

the point at which an object orbiting the Sun is closest to the Sun

Front 45

angular size (distance)

Back 45

a measure of the angle formed by extending imaginary lines outward from our eyes to span an object

Front 46

celestial navigation

Back 46

navigation on the surface of the Earth accomplished by observations of the Sun and stars

Front 47

Kepler's first law

Back 47

states that the orbit of each planet about the Sun is an ellipse with the Sun at one focus

Front 48

apparent retrograde motion

Back 48

the apparent motion of a planet, as viewed from Earth, during the period of a few weeks or months when it moves westward relative to the stars in our sky

Front 49

celestial equator

Back 49

the extension of the Earth's equator onto the celestial sphere

Front 50

focus

Back 50

the point at which rays of light that were initially parallel converge

Front 51

partial solar eclipse

Back 51

a solar eclipse during which the Sun becomes only partially blocked by the disk of the Moon

Front 52

fossil

Back 52

any relic of an organism that lived and died long ago

Front 53

celestial coordinates

Back 53

the coordinates of right ascension and declination that fix an object's position on the celestial sphere

Front 54

Kepler's laws of planetary motion

Back 54

three laws discovered by Kepler that describe the motion of the planets around the Sun

Front 55

retrograde motion

Back 55

motion that is backward compared to the norm

Front 56

ellipse

Back 56

a type of oval that happens to be the shape of bound orbits

Front 57

nodes

Back 57

the two points in the Moon's orbit where it crosses the ecliptic plane

Front 58

solar eclipse

Back 58

occurs when the Moon's shadow falls on the Earth, which can occur only at new moon

Front 59

scientific method

Back 59

an organized approach to explaining observed facts through science

Front 60

fall equinox

Back 60

the point in Virgo on the celestial sphere where the ecliptic crosses the celestial equator; the moment in time when the Sun appears at that point each year (September 21)

Front 61

south celestial pole

Back 61

the point on the celestial sphere directly above the Earth's South Pole

Front 62

circumpolar star

Back 62

a star that always remains above the horizon for a particular latitude

Front 63

lunar eclipse

Back 63

occurs when the Moon passes through the Earth's shadow, which can occur only at full moon

Front 64

theory of evolution

Back 64

the theory that explains how evolution occurs through the process of natural selection

Front 65

prime meridian

Back 65

the meridian of longitude that passes through Greenwich, England, defined to be longitude 0 degrees

Front 66

local sky

Back 66

the sky as viewed from a particular location on Earth; objects in the local sky are pinpointed by the coordinates of altitude and azimuth (direction)

Front 67

stellar parallax

Back 67

the apparent shift in the position of a nearby star that occurs as we view the star from different positions in the Earth's orbit of the Sun each year

Front 68

penumbral lunar eclipse

Back 68

a lunar eclipse in which the Moon passes only within the Earth's penumbral shadow and does not fall within the umbra

Front 69

apparent solar time

Back 69

time measured by the actual position of the Sun in your local sky defined so that noon is when the Sun is on the meridian

Front 70

partial lunar eclipse

Back 70

a lunar eclipse in which the Moon becomes only partially covered by the Earth's umbral shadow

Front 71

zenith

Back 71

the point directly overhead which has an altitude of 90 degrees

Front 72

saros cycle

Back 72

the period over which the basic pattern of eclipses repeats (about 18 years and 11 1/3 days)

Front 73

Kepler's third law

Back 73

the square of a planet's orbital period is proportional to the cube of its average distance from the Sun (semimajor axis); tells us that more distant planets move more slowly in their orbits

Front 74

latitude

Back 74

the angular north-south distance between the Earth's equator and a location on the Earth's surface

Front 75

Drake Equation

Back 75

an equation that lays out the factors that play a role in determining the number of communicating civilizations in our galaxy

Front 76

semimajor axis

Back 76

half the distance across the long axis of an ellipse (average distance of an orbiting object)

Front 77

Metonic cycle

Back 77

the 19 year period over which the lunar phases occur on the same dates

Front 78

habitable world

Back 78

a world with environmental conditions under which life could potentially arise or survive

Front 79

model

Back 79

a representation of some aspect of nature that can be used to explain and predict real phenomena without invoking myth, magic or the supernatural

Front 80

geological time scale

Back 80

the time scale used by scientists to describe major eras in Earth's past

Front 81

evolution

Back 81

the gradual change in populations of living organisms responsible for transforming life on Earth from its primitive origins to the great diversity of life today

Front 82

direction

Back 82

one of the two coordinates needed to pinpoint an object in the local sky; the direction in which you must face to see the object

Front 83

geocentric universe

Back 83

the idea that the Earth is the center of the entire universe

Front 84

hypothesis

Back 84

a tentative model proposed to explain some set of observed facts, but which has not yet been rigorously tested and confirmed

Front 85

total lunar eclipse

Back 85

a lunar eclipse in which the Moon becomes fully covered by the Earth's umbral shadow

Front 86

totality

Back 86

the portion of either a total lunar eclipse during which the Moon is fully within the Earth's umbral shadow or a total solar eclipse during which the Sun's disk is fully blocked by the Moon

Front 87

habitable zone

Back 87

the region around a star in which planets could potentially have surface temperatures at which liquid water could exist

Front 88

celestial sphere

Back 88

the imaginary sphere on which objects in the sky appear to reside when observed from Earth

Front 89

umbra

Back 89

the dark central region of a shadow

Front 90

Antarctic Circle

Back 90

the circle on the Earth with latitude 66.5 degrees S

Front 91

penumbra

Back 91

the lighter, outlying regions of a shadow

Front 92

summer solstice

Back 92

the point on the celestial sphere where the ecliptic is farthest north of the celestial equator; the moment in time when the Sun appears at that point each year (June 21)

Front 93

zodiac

Back 93

the constellations on the celestial sphere through which the ecliptic passes