Vocabulary

Axis--An imaginary straight line around which an object rotates.
Astronomical Unit ( AU)--The average distance from the Earth to the Sun, 93 million miles.
Circumpolar--Constellations that are close to the north or south celestial poles. These constellations do not set.
Constellation--A grouping of stars, considered by humans to form a picture in the sky. Often related to mythology.
Day--The time it take for a planet to make one full rotation (on Earth, 24 hours).
Diameter--The distance from one side of an object to another as measure through the center.
Gravity--The force of attraction between two objects which is influenced by the mass of two objects and the distance between the two objects.
Moon--A natural satellite orbiting a planet.
Orbit--A specific path followed by a planet, satellite, etc.
Planet--A massive object orbiting a star.
Radiate--Sends out rays or shines brightly.
Reflect--Light bouncing off an object.
Relative Distance--The distance between two objects as compared to something else.
Relative Size--The size of an object as compared to another object.
Revolution--The circling of a smaller object around a larger object.
Rotation--The spinning of an object on its axis.
Scale--Reducing or enlarging measurements by a ratio.
Scale Model--A model of an object that is a different size then the real objects.
Solar System--The system of planets, moons, and other objects revolving around a star (in our case, the Sun).
Star--A massive, self-luminous celestial body of gas that shines by radiation derived from its internal energy sources.
Sun (Sol)--the star that is closest to Earth and from which we get heat and light energy.
Universe--The vast expanse of space which contains all of the matter and energy in existence.
Year--The time it take for a planet to make one full revolution around a star, in our case, the Sun (on Earth, 365.25 days).