Study your flashcards anywhere!

Download the official Cram app for free >

  • Shuffle
    Toggle On
    Toggle Off
  • Alphabetize
    Toggle On
    Toggle Off
  • Front First
    Toggle On
    Toggle Off
  • Both Sides
    Toggle On
    Toggle Off
  • Read
    Toggle On
    Toggle Off

How to study your flashcards.

Right/Left arrow keys: Navigate between flashcards.right arrow keyleft arrow key

Up/Down arrow keys: Flip the card between the front and back.down keyup key

H key: Show hint (3rd side).h key

A key: Read text to speech.a key


Play button


Play button




Click to flip

57 Cards in this Set

  • Front
  • Back
the point on the celestial sphere that is directly above our heads at any given time.
Celestial meridian
the imaginary circle passing through north and south on the horizon and through the zenith.
“road of the sun;” the imaginary path that the sun follows on the celestial sphere over the course of a year
North/south celestial poles
Point on the celestial sphere directly above the Earth's north/south poles. The imaginary points about which the daily rotation of the sky appears to take place
the celestial equivalent of latitude; measured in degrees north (positive numbers) or south (negative numbers)
iii) Right ascension
the celestial equivalent of longitude; measures time
i) Vernal equinox
The equinox at which the sun approaches the Northern Hemisphere and passes directly over the equator.
ii) Summer solstice
point on the ecliptic where the sun is most north of the celestial equator during which daylight is longest in the northern hemisphere
iii) Winter solstice
point on the ecliptic where the sun is most south of the celestial equator diring which daylight is shortest in the northern hemisphere
i) Diurnal motion
daily motion of the celestial sphere. Affects all objects in the sky and does not change their relative positions: the diurnal motion causes the sky to rotate as a whole once every 24 hours.
ii) Proper motion
The angular movement of a star across the sky, as seen from Earth, measured in seconds of arc per year. This movement is a result of the star's actual motion through space.
i) Constellations
groupings of stars on the celestial sphere (e.g. Ursa Major).
ii) Asterism
a grouping of stars that is not officially recognized as a constellation (e.g. the Big Dipper).
i) Classical constellations
constellations recognized in ancient cultures that typically have mythological significance.
ii) Zodiac
an imaginary band on the celestial sphere that is eighteen degrees wide and centered on the ecliptic
iii) Constellations of the zodiac
12 constellations that lie in the zodiac
i) Bayer naming system
names brighter stars by assigning a constellation using the latin genitive case of the name and a greek letter in an approximate order of decreasing brightness for stars in the constellation (e.g alpha Orionis, beta Orionis)
ii) Flamsteed naming system
uses same latin name as bayer system, but assigns each star an Arabic numeral based on its nearness to the western edge of the constellation (e.g. 19-Orionis, 58-Orionis).
i) Inferior planets
the planets inside the orbit of earth (mercury and venus)
(1) Gibbous phases
phases of inferior planets between quarter and full phases
(2) Greatest elongation
refers to the largest separtation of the planet from the sun in our skiy, either to the east or to the west
(3) Inferior conjunction
when the dark side of the planet is turned toward earth; A planet is said to be in this when it is directly between the Earth and the Sun.
(4) Superior conjunction
when the lighted side of the planet faces earth; When a planet is in a straight line with the Earth and the Sun and is behind the Sun and as far from the Earth as it ever gets
iii) Inner planets
the planets inside the asteroid belt (a.k.a. the “terrestrial” planets) (mercury, venus, earth, mars).
iv) Outer planets
the planets outside of the asteroid belt (Jupiter, Saturn, Uranus, Neptune, Pluto).
v) Gas giant planets
the planets with a gas and liquid structure (a.k.a. “jovian”) (jupiter, Saturn, Uranus, Neptune).
i) Direct motion
the drift of planets in an eastern direction with respect to the stars on the celestial sphere
ii) Retrograde motion
a temporary, apparent backward and westward motion of a planet compared to the background stars.
iii) Sidereal period
The time it takes one object to complete one orbit around another
iv) Synodic period
how long it takes a planet to move on the celestial sphere and return to the same arrangement relative to the sun
i) Sidereal time
Time measured in relation to fixed stars, as distinguished from clock time, based upon the Sun's position relative to Earth. Astrological time data is listed in sidereal time units.
i) Sidereal day
the time for one complete rotation of the earth relative to a particular star, about 4 minutes shorter than a mean solar day
ii) Solar day
The period of time between the instant when the Sun is directly overhead (ie at noon) to the next time it is directly overhead.
i) Precession of the equinoxes
the right ascension and declination of objects changes very slowly over a 26,000-year period
ii) Sidereal month
Time required for the Moon to complete one trip around the celestial sphere (27.32 days)
iii) Synodic month
Time required for the Moon to complete a full cycle of phases. (about 29.5 days).
iv) Sidereal year
The time required for the constellations to complete once cycle around the sky and return to their starting points, as seen from a given point on Earth. (365.2564 mean solar days)
v) Tropical year
The time interval between one vernal equinox and the next. (365.2422 mean solar days)
i) Lunar calendar
a calendar based on lunar cycles
ii) Solar calendars
a calendar based on solar cycles
iii) Gregorian calendar
our present calendar; derived from roman lunar calendar
i) Tidal locking
Causes the moon’s rotational period and period of revolution to be equal—this is a consequence of the tidal forces acting between the earth and moon
ii) Librations
small deviations from perfect synchronization of the moon’s rotation and revolution. Because of librations, over a period of time, we can actually see about 59% of the lunar surface from earth.
iii) Lunation
the complete set of phases exhibited by the moon over its 29.5 day synodic cycle.
i) Umbra
the region of a shadow that is totally shaded
iii) Total eclipse
a solar eclipse in which the moon completely covers the bright surface of the sun; a lunar eclipse in which the moon completely enters the dark shadow of the earth
iv) Partial eclipse
a solar eclipse in which the moon does not completely cover the sun; a lunar eclipse in which the moon does not completely enter the earth’s shadow
v) Annular eclipse
a solar eclipse in which the solar photosphere appears around the edge of the moon in a bright ring, or annulus. The corona, chromosphere, and prominences cannot be seen
ii) Varying brightness
the planets were observed to be brighter at certain time than others
ii) Uniform circular motion
the classical belief that the perfect heavens could move only by the combination of uniform motion along circular orbits.
i) Epicycle
the small circle followed by a planet in the Ptolemaic theory. The center of the epicycle follows a larger circle (deferent)around earth
ii) Deferent
large circle around the earth along which the center of the epicycle moved
i) Heliocentric universe
a model of the universe with the sun at the center as introduced by Copernicus.
b) Inertia
The tendency of an object to continue in motion at the same speed and in the same direction, unless acted upon by a force.
a) Vectors
quantities that require not only a magnitude, but a direction to specify them completely
i) Velocity
A vector quantity equal to the rate that position changes with time
ii) Acceleration
The change in velocity as a function of time. Acceleration usually refers to increasing velocity and deceleration describes decreasing velocity.