Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
18 Cards in this Set
- Front
- Back
Lightyear
|
~ 9.46 × 10^15 m
the distance light travels in one year |
|
Proper motion
|
the motions of stars relative to one another
|
|
Celestial poles
|
the points where earth's axis intersects the celestial sphere
|
|
Diurnal motion
|
the daily progress of the Sun and other stars across the sky
|
|
Ecliptic path
|
the apparent motion of the Sun relative to background stars over the course of a year
|
|
Zodiac
|
the 12 constellations through which the Sun passes as it moves along the ecliptic
|
|
Summer solstice
|
the point on the ecliptic path where the Sun is at its northernmost point above the celestial equator
|
|
Autumnal equinox
|
Sept. 21
when the Sun passes the celestial equator moving south |
|
Vernal equinox
|
March 21
when the Sun passes the celestial equator moving north |
|
Tropical year
|
365.2422 mean solar days
the interval of time from one vernal equinox to the next |
|
Precession
|
the change in direction of the earth's axis over the course of time
|
|
Synodic month
|
the time required for the Moon to complete a full cycle of phases
|
|
Corona
|
the Sun's outer atmosphere
|
|
Umbra
|
the central region of the Moon's shadow during a solar eclipse
|
|
Penumbra
|
the area of partial solar eclipse - outside the umbra but still in the Moon's shadow
|
|
Annular eclipse
|
a Solar eclipse in which the Moon is too far away to cover the Sun
|
|
Line of nodes
|
the line joining the points on the Moon's orbit where it crosses the plane of the ecliptic
|
|
Eclipse seasons
|
points at which the line of nodes briefly lies along the Earth-Sun line
|