Astronomy Test 1

Front 1

the standard expression of numbers with one digit (which can be zero) to the left of the decimal point and multiplied by 10 to the exponent require to give the number its correct value.

Back 1

scientific notation

Front 2

the event that occurred 13.8 billion years ago that marks the beginning of time and the universe.

Back 2

big bang

Front 3

he (testable) assumption that the same physical laws that apply here and now also apply everywhere and at all times, and that there are no special locations or directions in the universe.

Back 3

cosmological principle

Front 4

the principle that the simplest hypothesis is the most likely

Back 4

Occam’s razor

Front 5

the formal procedure—including hypothesis, prediction, and experiment or observation—used to test (attempt to falsify) the validity of scientific hypothesis and theories

Back 5

scientific method

Front 6

all of the space and everything contained therein

Back 6

universe

Front 7

a large conglomeration of galaxy clusters and galaxy groups; typically more than 100 million light years (more than 30 Mpc) in size and containing tens of thousands to hundreds of thousands of galaxies.

Back 7

supercluster

Front 8

the small group of galaxies of which the Milky way and Andromeda galaxies are members

Back 8

local group

Front 9

the galaxy in which or sun and solar system reside

Back 9

milky way

Front 10

the gravitationally bound system made up of the sun, planets, dwarf planets, moons, asteroids, comets, and kuiper belt objects, along with their associated gas and dust

Back 10

solar system

Front 11

the distance that light travels in one year (about 9 trillion km)

Back 11

lightyear

Front 12

the imaginary great circle that is the projection of Earth’s equator onto the celestial sphere

Back 12

celestial equator

Front 13

the northward projection of earth’s rotation axis onto the celestial sphere

Back 13

north celestial pole

Front 14

he southward projection of earth’s rotation axis onto the celestial sphere

Back 14

south celestial pole

Front 15

the point on the celestial sphere located directly overhead from an observer

Back 15

zenith

Front 16

the point on the celestial sphere located directly below an observer

Back 16

nadir

Front 17

the angular distance north (+) or south (-) from the equatorial plane of a nearly spherical body

Back 17

latitude

Front 18

the slow change in orientation between the ecliptic plane and the celestial equator caused by the wobbling of earth’s axis

Back 18

precession

Front 19

the average distance between from the sun to earth: approximately 150 million km

Back 19

astronomical unit

Front 20

the constellation lying along the plane of the ecliptic

Back 20

zodiac

Front 21

1) the apparent annual path of the sun against the background of stars 2)the projection of earth's orbital plane onto the celestial sphere

Back 21

ecliptic

Front 22

1) one of the two points where the sun crosses the celestial equator 2) the day on which the sun appears at this location, marking the first day of spring

Back 22

vernal equinox

Front 23

1) one of two points where the sun crosses the celestial equator 2) the day on which the sun appears at this location, marking the first day of autumn

Back 23

autumnal equinox

Front 24

1) one of two points where the sun is at its greatest distance from the celestial equator 2) the day on which the sun appears at this location, marking the first day of winter

Back 24

winter solstice

Front 25

an eclipse that occurs when the sun is partially or entirely blocked by the moon

Back 25

solar eclipse

Front 26

an eclipse that occurs when the moon is partially or entirely in earth’s shadow

Back 26

lunar eclipse

Front 27

the case in which the period of rotation of a body on its axis equals the period of revolution in its orbit around another body. a special type of spin-orbit resonance

Back 27

synchronous rotation

Front 28

a coordinate system having the center of the sun as its center

Back 28

heliocentric

Front 29

a coordinate system having earth at its center

Back 29

geocentric

Front 30

1) rotation or orbital motion of a moon that is in the opposite sense to the rotation of the planet it orbits 2) the clockwise orbital motion of solar system objects

Back 30

retrograde motion

Front 31

a conic section produced by the intersection of a plane with a cone when the plane is passed through the cone at an angle to the axis other than 0 degrees or 90 degrees

Back 31

ellipse

Front 32

is the brightest star in the constellation of Ursa Minor. It is very close to the north celestial pole, making it the current northern pole star.

Back 32

polaris

Front 33

type of photograph that utilizes long-exposure times to capture the apparent motion of stars in the night sky due to the rotation of the Earth

Back 33

star trail

Front 34

the angle between an object's rotational axis and its orbital axis, or, equivalently, the angle between its equatorial plane and orbital plane

Back 34

tilt of the earth

Front 35

each of the four divisions of the year (spring, summer, autumn, and winter) marked by particular weather patterns and daylight hours, resulting from the earth's changing position with regard to the sun.

Back 35

season

Front 36

the action of rotating around an axis or center

Back 36

rotation

Front 37

a single orbit of one object around another or about an axis or center

Back 37

revolution

Front 38

either of the two points at which a planet's orbit intersects the plane of the ecliptic or the celestial equator

Back 38

node

Front 39

the apparent diameter of a planet or other celestial object measured by the angle that it subtends at the point of observation

Back 39

angular diameter

Front 40

geometric model used to explain the variations in speed and direction of the apparent motion of the Moon, Sun, and planet

Back 40

epicycle