History
Babylonian astronomers in the first millennium B.C.E. observed that the Sun's motion along the ecliptic was not uniform, though they were unaware of why this was; it is today known that this is due to the Earth moving in an elliptic orbit around the Sun, with the Earth moving faster when it is nearer to the Sun at perihelion and moving slower when it is farther away at aphelion.
In the 17th century, Johannes Kepler discovered that the orbits along which the planets travel around the Sun are ellipses with the Sun at one focus, in his first law of planetary motion. Later, Isaac Newton explained this as a corollary of his law of universal gravitation.
Read more about this topic: Elliptic Orbit
Famous quotes containing the word history:
“The history of the Victorian Age will never be written: we know too much about it.”
—Lytton Strachey (1880–1932)
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“... in America ... children are instructed in the virtues of the system they live under, as though history had achieved a happy ending in American civics.”
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