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the point along a planet's orbit at which it is farthest from the Sun


a closed curved line on which all points are of equal distance from its center

drawing compass

a mechanical device used to draw circles


A shape like a stretched-out circle; an oval

focus (foci)

the point at the center of a circle


the attractive force between objects


the elliptical path that a satellite travels as it moves around a star or planet


the point along a planet's orbit at which it is nearest to the Sun

radius (radii)

the distance on a circle from the focus to the circumference


a relationship between two measurements

relative distance

the distance between objects when compared with the distance between surrounding objects


an object in orbit around a larger object


a group of items that form a unified whole


the distance from one side of a circle, through the focus, to the other side


a large, spherical satellite of a star

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