kepler's first law
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Kepler's first law describes the elliptical orbit of a planet around the sun.
Definition
Noun: A fundamental law of planetary motion stating that the orbit of a planet around the Sun is an ellipse, with the Sun located at one of the two foci of that ellipse.
Usage
This term is used exclusively in the context of astronomy and physics to describe the shape and geometric property of a planetary orbit. It is the first of Kepler's three laws of planetary motion.
Examples
- In a textbook:
- In an explanation:
Advanced Usage
- Historical Context: The law is named after the astronomer Johannes Kepler, who published it in 1609. It replaced the ancient belief that planetary orbits were perfect circles.
- Scientific Implication: This law implies that a planet's distance from the Sun varies throughout its orbit, being closest at perihelion and farthest at aphelion.
Variants and Related Words
- Kepler's Laws of Planetary Motion: The collective term for Kepler's first, second, and third laws.
- Ellipse (n): The oval-shaped path described by Kepler's first law.
- Focus (n, pl. foci): One of the two fixed points inside an ellipse used to define its shape; the Sun occupies one focus.
Synonyms
- Law of Ellipses: A descriptive synonym for Kepler's first law.
Related Phrases
- Planetary motion: The general movement of planets, which Kepler's laws describe.
- Orbital mechanics: The field of study that applies Kepler's laws.
Kepler's first law describes the elliptical orbit of a planet around the sun.
Noun
- a law stating that the orbit of each planet is an ellipse with the sun at one focus of the ellipse