Earth Science Vocab Review 1

Front

aphelion

Back

The point in an orbit where a planet is farthest from the Sun.

Front

apparent retrograde motion

Back

The perceived backward movement of a planet against the background stars due to the relative motion of Earth and the planet.

Front

eccentricity

Back

A measure of how an orbit deviates from being circular.

Front

ellipse

Back

An elongated circle, the shape of orbits of planets.

Front

exoplanet

Back

A planet located outside our solar system.

Front

focal points (focus)

Back

The two fixed points in an ellipse used to define its shape.

Front

gravity

Back

The force that attracts two bodies towards each other, proportional to their masses and inversely proportional to the square of the distance between them.

Front

Kepler’s laws

Back

The three laws describing the motion of planets around the Sun.

Front

nebula

Back

A cloud of gas and dust in space, often the site of star formation.

Front

newton (N)

Back

The SI unit of force, named after Sir Isaac Newton.