Month: July 2025

MEAN ANOMALY – The fraction of an orbit’s period that has elapsed since perihelion, measured in degrees.

KEPLER’S EQUATION – A mathematical formula used to describe a planet’s position along its elliptical orbit.

ORBITAL RESONANCE – When two orbiting bodies exert periodic gravitational influence on each other.

TYCHO BRAHE – The astronomer whose precise observational data helped Kepler develop his laws.

JOHANNES KEPLER – The astronomer who formulated the three laws of planetary motion.

SYNODIC PERIOD – The time between successive identical configurations of a planet, as seen from Earth.

SIDEREAL PERIOD – The actual time it takes for a planet to complete one full orbit relative to distant stars.

ASTRONOMICAL UNIT (AU) – The average distance from the Earth to the Sun, about 93 million miles (150 million km).

ORBITAL PERIOD – The time a planet takes to complete one full orbit around the Sun.

PERIHELION – The point in a planet’s orbit closest to the Sun.