acceleration

law of universal gravitation

air drag

major axis (of an ellipse)

aphelion

mass

conic section

neap tides

conjunction

Newtonian mechanics

conservation of energy

Newton’s first law of motion

deferent

Newton’s form of Kepler’s third law

direct motion

Newton’s second law of motion

eccentricity

Newton’s third law of motion

ellipse

Occam’s razor

elongation

opposition

epicycle

orbital energy

escape speed

parabola

focus (of an ellipse; plural foci)

parallax

force

perihelion

geocentric model

period (of a planet)

gravitational force

Ptolemaic system

gravitational potential energy

retrograde motion

gravity

semimajor axis (of an ellipse)

greatest eastern elongation

sidereal period

greatest western elongation

speed

heliocentric model

spring tides

hyperbola

superior conjunction

inferior conjunction

superior planet

inferior planet

synodic period

Kepler’s first law

tidal forces

Kepler’s second law

universal constant of gravitation

Kepler’s third law

velocity

kinetic energy

weight

law of equal areas