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Astronomy Chapter 2
Astronomy
Question | Answer |
---|---|
constellation | a region of the sky with well defined borders |
celestial sphere | the illusion of a sphere that encompasses the earth |
North celestial pole | point which lies directly over the North Pole |
South celestial pole | point which lies directly over the South Pole |
celestial equator | projection of Earth's equator into space |
ecliptic | path the sun follows |
number of constellations | 88 |
galactic plane | our galaxy's disk of stars |
local sky | the sky as seen from where you are standing |
horizon | boundary between Earth and sky |
zenith | point directly overhead |
meridian | imaginary half-circle stretching from the horizon from N to S |
azimuth | direction of object along the horizon - measured in degrees |
altitude | position of object from between earth and sky |
angular size | angle that an object appears to span |
angular distance | angle that appears to separate two objects |
arcminutes | one degree divided by 60 |
arcseconds | one arcminute divided by 60 |
circumpolar | stars that never rise but make daily counterclockwise circles |
latitude | measures N to S |
longitude | measures E to W |
prime meridian | line of longitude at 0 degrees - runs through Greenwich, England |
sky visibility | sky varies with latitude |
zodiac | constellations along the ecliptic |
Earth's orbit | summer solstice, winter solstice, spring equinox, fall equinox |
precession | a gradual wobble that changes the orientation of Earth's axis |
lunar phases | new moon, waxing crescent, first quarter, waxing gibbous, full moon, waning gibbous, third quarter, waning crescent |
synchronous rotation | moon must rotate once as it makes a single orbit around the Earth |
lunar eclipse | earth's shadow falls on moon |
solar eclipse | moon's shadow falls on earth |
nodes | two points at which the moon crosses the surface of the earth |
umbra | sunlight is completely blocked |
penumbra | sunlight is partially blocked |
total lunar eclipse | moon passes through earth's umbra - moon turns red |
partial lunar eclipse | part of moon passes through earth's umbra |
penumbral lunar eclipse | moon passes thought earth's penumbra |
total solar eclipse | moon comes between sun and earth - moon looks black |
partial solar eclipse | moon appears red in a crescent form |
annual eclipse | a ring of sunlight surrounds the disk of the moon |
eclipse seasons | two periods where the nodes of the moon's orbit are aligned with the sun |
saros cycle | changing dates of eclipse seasons |