Ch. 2 - User's Guide To The Sky: Patterns And Cycles

Front 1

Zenith

Back 1

The point in the sky directly above the observer

Front 2

Arc Second

Back 2

1/60th of an arc minute

Front 3

Sidereal period

Back 3

The period of rotation or revolution of an astronomical body relative to the stars

Front 4

Asterisms

Back 4

A named grouping of stars that is not one of the recognized constellations

Front 5

Aphelion

Back 5

The orbital point of greatest distance from the sun

Front 6

Flux

Back 6

A measure of the flow of energy through a surface, usually applied to light

Front 7

North Celestial Pole

Back 7

The points on the celestial sphere directly above Earth's north and south poles

Front 8

Angular Distance

Back 8

The angle formed by lines extending from the observer to two locations in the sky

Front 9

Nadir

Back 9

The point on the celestial sphere directly below the observer. opposite of the zenith

Front 10

Summer Solstice

Back 10

The point on the celestial sphere where the sun is at its most northerly point - also the beginning of summer

Front 11

North Point

Back 11

The four cardinal directions, the points on the horizon in those exact directions

Front 12

Precession

Back 12

The slow change in orientation of the Earths axis rotation. Once cycle takes nearly 26,000 years.

Front 13

Autumnal Equanox

Back 13

The point on the celestial sphere where the sun crosses the celestial equator going southward - also the beginning of autumn

Front 14

Solar Eclipse

Back 14

The event that occurs when the moon passes directly between Earth and the sun, blocking your point of view

Front 15

Punumbra

Back 15

The portion of shadow that is only partially shaded.

Front 16

Winter Soltice

Back 16

The point on the celestial Sphere where the Sun is the farthest south.

Front 17

Saros Cycle

Back 17

An 18-year, 11⅓-day period after whichthe pattern of lunar and solar eclipses repeats.

Front 18

Vernal Equanox

Back 18

The place on the celestial sphere where the sun crosses the celestial equator moving northward - also the beginning of spring

Front 19

Horizon

Back 19

The circular boundary between the sky and Earth

Front 20

Evening Star

Back 20

Any planet visible in the sky just after sunlight

Front 21

Synodic Period

Back 21

The Period of rotations or revolutions of a celestial body with respect to the sun

Front 22

Arc Minutes

Back 22

1/60th of a degree.

Front 23

Magnitude Scale

Back 23

The astronomical brightness scale. Thelarger the number, the fainter the star.

Front 24

Annular Eclipse

Back 24

A solar eclipse in which the polarphotosphere appears around the edgeof the moon in a right ring, or annulus.Features of the solar atmospherecannot be seen during an annulareclipse.

Front 25

Circumpolar constellations

Back 25

Any of the constellations to close so thecelestial poles that they never set (ornever rise) from a given location.

Front 26

Lunar Eclipse

Back 26

The darkening of the moon when itmoves through Earth’s shadow.

Front 27

Scientific Model

Back 27

A scientific metaphor; a concept thatorganizes thought about an aspect ofnature without necessarily beingliterally true.

Front 28

Revolution

Back 28

Orbital motion about a point located outside the orbiting body.

Front 29

Apparent Visual Magnitude (Mv)

Back 29

A measure of the brightness of a star as seen by human eyes on earth

Front 30

Umbra

Back 30

The region of a shadow that is totally shaded

Front 31

Contellations

Back 31

One of the stellar patterns identified by name, usually of mythological gods, people, animals or objects. Also the region of the sky containing that star pattern

Front 32

Celestial equator

Back 32

The imaginary line around the sky directly above the earth's equator

Front 33

Morning Star

Back 33

Any planet visible in the sky just before sunrise

Front 34

Perihelion

Back 34

The orbital point of closest approach to the sun

Front 35

Zodiac

Back 35

A band centered on the ecliptic and encircling the sky

Front 36

Rotation

Back 36

Motion around an axis passing the the rotating body

Front 37

Celestial Sphere

Back 37

An imaginary sphere of very large radius surrounding Earth to which the planets, stars, sun, and moon seem to be attatched

Front 38

Ecliptic

Back 38

The apparent path of the sun around the sky

Front 39

Angular Diameter

Back 39

The angle formed by lines extending from the observer to opposite edges of an object

Front 40

East Point

Back 40

The four cardinal directions; the point on the horizon in those exact directions

Front 41

South Celestial Pole

Back 41

The points on the celestial sphere directly above earth's north and south poles

Front 42

South Point

Back 42

The four cardinal directions; the points on the horizon in those exact direction

Front 43

West Point

Back 43

The four cardinal directions; the points on the horizon in those exact directions

Front 44

Apparent Visual Magnitude

Back 44

A measure of brightness of a star as seen by human eyes on Earth

Front 45

Arc Minute

Back 45

1/60th of a degree

Front 46

Arc Second

Back 46

1/60 of an arc minute

Front 47

Asterism

Back 47

A named grouping of stars that is not one of the recognized constellations

Front 48

Circumpolar Constellation

Back 48

Any of the constellations so close to the celestial poles that the never set or never rise from a given location

Front 49

Constellation

Back 49

One of the stellar patterns identified by name of mythological gods, people, animals, or objects. Also the region of the sky containing that star pattern.

Front 50

North and South Celestial Poles

Back 50

The points on the celestial sphere directly above Earth's north and south poles

Front 51

New Moon

Back 51

A solar eclipse can only be observed when the moon is in this position

Front 52

Zenith

Back 52

The point on the celestial sphere directly above an observer who can be at any point on the Earth

Front 53

Magnitude Scale

Back 53

Can be used to indicate the apparent intensity of a celestial object

Front 54

The Big Dipper

Back 54

Is an asterism

Front 55

Precession

Back 55

The apparent motion that the celestial poles and equator slowly move relative to the stars