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15 Cards in this Set

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circumpolar stars
do not rise or set; simply rotate around Polaris. never go below horizon
At equator, none. Polaris is on horizon.
As altitude increases, more and more circumpolar stars
At North Pole, all
Altitude of Pole Star=
Observer's latitude
Rotation
Earth rotates West to East.
See objects in sky move from East to West
AM vs PM
Noon=sun crosses observer's meridian
Angles
Arcminute=60th of a degree
Arcsecond=60th of an arcminute
Revolution
rotates counterclockwise about axis and revolves counterclockwise around sun
Ecliptic
apparent path of sun thru the 13 constellations
projection of earth's orbit around sun
Equinox
when ecliptic and celestial equator intersect
days have 12 hour of sunlight everywhere
Declination
value of 0 at equator and increases towards Poles; latitude
Celestial poles have declination of 90
vernal equinox
sun crosses from southern hemisphere to northern hemisphere. first day of spring
autumnal equinox
sun crosses from northern hemisphere into southern
Solstice
sun is farthest away from celestial equator
summer: sun is highest in sky at noon, first day of summer
Winter: sun is lowest in sky at noon, first day of winter
perihelon
closest approach to sun, in january
aphelion
farthest approach to sun, in july
precession
earth wobbles
positions of north and south celestial poles change over course of 26000 years