8.05 The Earth in Space

sundials

invented in the 16th century to track time based on the sun’s shadows

elliptical

Earth’s orbit around the sun

perhelion

point in Earth’s orbit when it is closest to the sun

aphelion

point in Earth’s orbit when it is furthest from the sun

period (P)

time it takes a planet to complete one complete orbit around the sun

Kepler’s second law

states that the closer a planet is to the sun, the faster it revolves due to the gravititational force between the sun and the planet

apogee

point when the moon is farthest from the Earth

perigee

point when the moon is the closest to Earth

marias

darkened areas on the moon

highlands

lighter areas on the moon

regolith

powdery soil-like substance formed by meteoroids’ impact

Earth’s tilt

changes the angle of sunlight throughout the year

temperature variations

depends on a location’s distance from the equator

latitude lines

distance from the equator is measured in degrees

Seasons

periods of climate changes influenced by Earth’s orbit and axis tilt

leap year

every fourth year has one extra day to align with the Earth-Sun system’s orbital period