Definition

Noun: 1. Kepler's law: (astronomy) one of three empirical laws of planetary motion stated by Johannes Kepler. These are fundamental physical laws that describe the motion of planets around the Sun.

Usage

The term "Kepler's law" is used in scientific and educational contexts to refer to any one of the three specific principles discovered by Johannes Kepler. It is often used in the plural ("Kepler's laws") when discussing all three together. * The professor explained how Kepler's law of equal areas proved that a planet moves faster when it is closer to the Sun. * Understanding Kepler's laws is essential for calculating satellite orbits.

Advanced Usage

• Kepler's First Law (Law of Ellipses): The orbit of a planet is an ellipse with the Sun at one of the two foci.
• Kepler's Second Law (Law of Equal Areas): A line segment joining a planet and the Sun sweeps out equal areas during equal intervals of time.
• Kepler's Third Law (Law of Harmonies): The square of the orbital period of a planet is directly proportional to the cube of the semi-major axis of its orbit.

Variants and Related Words

• Kepler's laws (noun, plural): The collective term for all three laws of planetary motion.
• Law of planetary motion (noun): A more general term for which Kepler's laws are the specific, historically significant examples.
• Newton's law of universal gravitation (noun): The fundamental physical law that mathematically explains and derives Kepler's laws.

Synonyms

• Law of planetary motion
• Keplerian law

Related Phrases

• To obey/follow Kepler's laws: Describes the motion of celestial bodies.
  • All planets in our solar system obey Kepler's laws.
• To derive Kepler's laws: Refers to the mathematical process of showing how the laws follow from a more fundamental theory (like Newtonian gravity).
  • Newton was able to derive Kepler's laws from his law of universal gravitation.

Noun

1. (astronomy) one of three empirical laws of planetary motion stated by Johannes Kepler