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15 Cards in this Set
- Front
- Back
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circumpolar stars
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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 |
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Altitude of Pole Star=
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Observer's latitude
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Rotation
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Earth rotates West to East.
See objects in sky move from East to West |
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AM vs PM
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Noon=sun crosses observer's meridian
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Angles
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Arcminute=60th of a degree
Arcsecond=60th of an arcminute |
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Revolution
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rotates counterclockwise about axis and revolves counterclockwise around sun
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Ecliptic
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apparent path of sun thru the 13 constellations
projection of earth's orbit around sun |
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Equinox
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when ecliptic and celestial equator intersect
days have 12 hour of sunlight everywhere |
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Declination
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value of 0 at equator and increases towards Poles; latitude
Celestial poles have declination of 90 |
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vernal equinox
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sun crosses from southern hemisphere to northern hemisphere. first day of spring
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autumnal equinox
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sun crosses from northern hemisphere into southern
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Solstice
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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 |
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perihelon
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closest approach to sun, in january
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aphelion
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farthest approach to sun, in july
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precession
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earth wobbles
positions of north and south celestial poles change over course of 26000 years |
