| A | B |
|---|
| rotation | the act or process of turning around a center or an axis |
| revolution | a turning or rotational motion about an axis |
| axis | a straight line about which a body or geometric object rotates or is conceived to rotate |
| intensity | exceptionally great concentration, power or force |
| photoperiod | a recurring cycle of light and dark periods of constant length |
| Sun | huge star over 93 million miles away, an enormous ball of very hot gas |
| Earth | a small planet shaped like a ball that orbits around the sun |
| day | period of daylight hours; time when we face the Sun |
| night | period of darkness; time when we don't face the Sun |
| spin | to cause to rotate swiftly |
| arc | something shaped like a curve or arc |
| model | a small-sized copy of something |
| angle | the figure formed by two lines or flat surfaces that extend from one point or line |
| sphere | a round 3-dimensional figure like a ball |
| tilt | to cause to slope, as by raising one end |
| clockwise | in the direction in which the hands of a clock move |
| counterclockwise | in the direction opposite in which the hands of a clock move |
| equinox | either of the 2 times during the year when the sun crosses the celestial equator; the length of day and night are about equal (vernal and autumnal) |
| solstice | either of the 2 times of the year when the sun is at its greatest distance from the celestrial equator |
| year | 365 days; the time it takes Earth to complete its rotation around the sun |
| degree | unit for measuring angles or arcs |
