Earth-Sun Geometry
Polaris
the North Star
Tropic of Cancer
23.5 degrees North
Tropic of Capricorn
23.5 degrees South
revolution
Earth's annual trip around the Sun
rotation
Earth's spinning motion
insolation
how Earth's orbit around the Sun and its orientation with respect to incoming radiation influence the seasonal and latitudinal receipt of incoming solar radiation
ecliptic plane
the imaginary surface Earth rides along to orbit the Sun
beam spreading
the increase int he surface area over which radiation is distributed in response to a decrease of solar angle
aphelion
when Earth is farthest from the Sun
perihelion
when Earth is nearest to the Sun
March and September equinoxes
when every place on Earth has 12 hours of day and night and both hemispheres receive equal amounts of energy
June solstice
when the Northern Hemisphere has its maximum tilt toward the Sun (AKA summer solstice)
December solstice
when the Northern Hemisphere has its minimum availability of solar radiation (AKA winter solstice)