any round object that has a surface that is the same distance from its center at all points, for example, a ball or globe
sphere
to turn around a center point or axis. The Earth does this on its axis
rotate
one half of a sphere or globe. The Earth is divided at the equator into the Northern and Southern
hemisphere
without turning or stopping; straight; the shortest way
direct
an imaginary line around the middle of the Earth, at an equal distance from the North Pole and the South Pole
equator
not straight; by a longer way
indirect
a real or imaginary straight line about which something turns. The imaginary line of the Earth passes through the North and South Pole
axis
either of two times of the year when the sun is farthest from the equator in the north or south
solstice
the path followed by a planet, moon, or other heavenly body as it travels around another body. The path of the Earth around the Sun is an orbit
orbit
either of two times of the year when the sun crosses the plane of the earth's equator and day and night are of equal length
equinox