astronomy pt. 2 Flashcards
what is the difference between the earth’s rotation and revolution?
rotation: produces day and night
revolution: one year (365.24 days)
how fast does the earth move around the sun?
67,000 mph
when is earth closest to the sun?
around january 2 (147 million km)
when is earth farthest from the sun?
around july 4 (152 million km)
how do we know that the earth revolves around the sun?
parallax
what is parallax?
the apparent shift in position of a nearby star in relation to distant stars
what are seasons caused by?
3 things
- earths revolution
- earths tilt
- earths axis is always pointed toward polaris
- parallelism of the axis
what degree is earth’s tilt?
23.5°
if the earth didn’t revolve and was not tilted, what season would be at each location all year long?
- equator
- poles
- erie
equator: always summer
poles: always winter
erie: always “sprall”
when is the summer solstice? where are the suns direct rays?
around july 21st
tropic of cancer (23.5° N)
when is the winter solstice?
where are the suns direct rays?
around december 21st
tropic of capricorn (23.5° S)
when is the spring/fall equinox?
where are the suns direct rays?
around march 21st & september 21st
the sun is directly overhead at the equator
how many hours of daylight is there in each season?
winter- 8 hours
summer- 15 hours
spring/fall- 12 hours
what is precession?
the movement of the earth’s axis
how long does it take for the earth to “wobble” one full cycle?
26,000 years
what is zenith?
when the sun is directly overhead
what controls the tropics?
the earth’s tilt
where does the sun rise and set in the winter/fall?
rises- SE
sets- SW
where does the sun rise and set in the spring/summer?
rises- NE
sets- NW
when does the sun rise and set exactly in the east and west?
during the equinoxes
what is the celestial equator? how do you calculate it?
the projection of the earth’s equator into space
subtract the current latitude by 90°
what is erie’s latitude?
approximately 42° N
what is the ecliptic?
the path that the sun travels in the sky
what is the waxing moon phase?
waning?
waxing- revolving toward full
waning- revolving toward new
