Earth and Space Vocabulary

horizon

the line at which the earth's surface and the sky appear to meet

navigate

plan and direct the route or course of a ship, aircraft, or other form of transportation, especially by using instruments or maps

sphere

a round solid figure

equator

an imaginary line dividing the earth into northern and southern hemispheres

gravity

the force that attracts a body toward the center of the earth

axis

an imaginary line around which an object rotates

rotation

the circular movement of an object around a central axis

revolution

the movement of an object around another

altitude

the apparent height of an object above the horizon

constellation

a group of stars in the sky, usually named after some object, animal, or mythological being