Astronomy Ch 2

Front 1

angular diameter

Back 1

The angle formed by lines extending from the observer to opposite sides of an object. (p. 21)

Front 2

angular distance

Back 2

The angle formed by lines extending from the observer to two locations. (p. 21)

Front 3

apparent visual magnitude (mv)

Back 3

The brightness of a star as seen by human eyes on Earth. (p. 16)

Front 4

asterism

Back 4

A named grouping of stars that is not one of the recognized constellations. Examples are the Big Dipper and the Pleiades. (p. 15)

Front 5

celestial equator

Back 5

The imaginary line around the sky directly above Earth's equator. (p. 20)

Front 6

celestial pole (north or south)

Back 6

One of the two points on the celestial sphere directly above Earth's poles. (p. 20)

Front 7

celestial sphere

Back 7

An imaginary sphere of very large radius surrounding Earth and to which the planets, stars, sun, and moon seem to be attached. (p. 20)

Front 8

circumpolar constellation (north or south)

Back 8

A constellation so close to one of the celestial poles that it never sets or never rises as seen from a particular latitude. (p. 21)

Front 9

constellation

Back 9

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. (p. 14)

Front 10

east point

Back 10

One of the four cardinal directions. The point on the horizon directly east. (p. 20)

Front 11

horizon

Back 11

The circular boundary between the sky and Earth. (p. 20)

Front 12

magnitude scale

Back 12

The astronomical brightness scale. The larger the number, the fainter the star. (p. 15)

Front 13

minute of arc

Back 13

An angular measure. One sixtieth of a degree. (p. 21)

Front 14

model

Back 14

See scientific model.

Front 15

nadir

Back 15

The point on the celestial sphere directly below the observer. The opposite of the zenith. (p. 20)

Front 16

north celestial pole

Back 16

The point on the celestial sphere directly above Earth's North Pole. (p. 20)

Front 17

north point

Back 17

One of the four cardinal directions. The point on the horizon directly north. (p. 20)

Front 18

precession

Back 18

The slow change in the direction of Earth's axis of rotation. One cycle takes nearly 26,000 years. (p. 18)

Front 19

scientific model

Back 19

A tentative description of a phenomenon for use as an aid to understanding. (p. 18)

Front 20

second of arc

Back 20

An angular measure. One sixtieth of a minute of arc. (p. 21)

Front 21

south celestial pole

Back 21

The point on the celestial sphere directly above Earth's South Pole. (p. 20)

Front 22

south point

Back 22

One of the four cardinal directions. The point on the horizon directly south. (p. 20)

Front 23

west point

Back 23

One of the four cardinal directions. The point on the horizon directly west. (p. 20)

Front 24

zenith

Back 24

The point on the sky directly above the observer. (p. 20)