Astronomy Test 1B study guide

study of celestial objects, space, and the physical universe

astronomy

Phases in which we see decreasing portions of the day side of the moon as time goes forward.

waning

Another name for a star wheel that helps you find stars by lining up the date and the time.

planisphere

an imaginary sphere of which the observer is the center and on which all celestial objects are considered to lie.

celestial sphere

Phases in which we see an increasing percentage of the day side of the moon as time goes forward

waxing

the projection into space of the earth's equator; an imaginary circle equidistant from the celestial poles.

celestial equator

Each of the two times of the year when days and nights are of equal length

equinox

the time it takes for the Earth to complete one full rotation relative to the distant stars, which is approximately 23 hours, 56 minutes, and 4 seconds.

sidreal day

When a shadow of one object falls upon another.

eclipse

Time when the Sun is farthest from the equator.

solstice

a thin ring from the moon that appears when it passes in front of the sun

annulus

figure-eight shape that the sun traces out in the sky each day

analemma

constellations that are close enough to the celestial pole that they are visible all night, year-round

circumpolar

The visible daily (24-hour) motion of the stars caused by earth's rotation

diurnal motion

the time it takes for the Earth to rotate enough to bring the Sun back to the same position in the sky, which is approximately 24 hours.

solar day

Know the phases of the moon in order

New Moon, Waxing Crescent, First Quarter, Waxing Gibbous, Full Moon, Waning Gibbous, Third Quarter, and Waning Crescent

The motion of the planets is complicated because their apparent motion in the sky is the combination of their ________ ___________ around the sun, plus the ___________ ____________ in position due to Earth's motion around the sun.

true motion, apparent shift

In the solar system, planets orbit in ____________ paths.

elliptical

A coordinate system based on the celestial sphere. In particular, they are based on the celestial equator.

Equatorial coordinates system

A coordinate based on the observer's local position and defines the position of an object in the sky using two angles: altitude and azimuth.

Local Horizon Coordinate System

Measured eastward along the celestial equator from the vernal equinox, and expressed in hours, minutes, and seconds.

Right Ascension (RA)

Measured north or south of the celestial equator in degrees. Positive values indicate positions north of the celestial equator, while negative values indicate positions south.

Declination (Dec)

the period over which the basic pattern of eclipses repeats, which is about 18.6 years

saros cycle

The darkest part of the moon's shadow

umbra

the lighter part of a shadow where light is partially blocked

penumbra

the visible surface of the sun

photosphere

Icy objects that follow an extremely elliptical orbit

Comets

The terms "inferior" and "superior" refer to a planet's position relative to Earth's orbit around the Sun. Inferior planets include:

Mercury and Venus

The terms "inferior" and "superior" refer to a planet's position relative to Earth's orbit around the Sun. Superior planets include:

Mars, Jupiter, Saturn, Uranus, Neptune

Memorize Psalm 19:1 (NLT)

“The heavens proclaim the glory of God. The skies display his craftsmanship.”