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Exam 1
Planetary Astronomy
Term | Definition |
---|---|
Relative stellar coordinates | altitude and azimuth |
altitude | distance above the horizon measured in degrees |
azimuth | distance along the horizon measured in degrees from due north |
zenith | 90 degrees |
one degree altitude | width of your pinky |
five degrees altitude | width of three fingers |
ten degrees altitude | width of your fist |
fifteen degrees altitude | width of stretched index and pinky finger |
twenty-five degrees altitude | width of stretched thumb and pinky finger |
zero degrees azimuth | north |
ninety degrees azimuth | east |
one-hundred and eighty degrees azimuth | south |
two-hundred and seventy degrees azimuth | west |
absolute stellar coordinates | declination and right ascension |
declination | a measure above or below the celestial equator measured in degrees |
right ascension | a measure along the celestial equator measured in hours, minutes, and seconds |
celestial equator | a line running due east to due west across the sky |
ecliptic | the sun's annual path across the background stars |
summer solstice | the point where the sun is highest along its path |
winter solstice | the point where the sun is lowest along its path |
equinox | the point where the sun's path crosses the celestial equator |
seasonal progression | the sun's tilted path through the sky with respect to the celestial equator at an angle of 23.5 degrees |
solar eclipse | moon blocks the sun (only during new moon) |
lunar eclipse | moon moves into earth’s shadow (only during full moon) |
diurnal motion | how all objects in the heavens appear to move from east to west across the sky |
gregorian calendar | 365.2425 days in a year |
metonic cycle | a period of 19 years where the new/full moons return to the same days of the year |