Orbit converter
Convert an orbit around the Sun between its distance, its year and its speed. Kepler’s law ties all three together.
That's about the same as Earth. A year out there lasts about 1 Earth years.
What it means
How long is its year?
Kepler’s law here assumes the Sun’s mass and a circular orbit. Real orbits are ellipses, and the semi-major axis is what goes into the formula.
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Your orbit in every unit
Learn
Three things worth knowing
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T² = a³
With the period in years and the distance in astronomical units, the constants vanish and the law is that simple.
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Ten years of arithmetic
Kepler tried and discarded dozens of relationships before finding this one in Tycho Brahe’s observations. Newton later showed it falls straight out of gravity.
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Further is slower
Neptune’s year is 165 times Earth’s, but its orbit is only 30 times wider. It also travels at a fifth of Earth’s speed, which stretches the year further still.
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Background
About Kepler’s third law
The further out a planet orbits, the slower it goes and the longer its year — and the relationship is exact: the period in years is the distance in AU raised to the power 3/2.
Jupiter at 5.2 AU takes 11.9 years. Neptune at 30 AU takes 165. Nobody needed to know the masses to work that out; Kepler got it from Tycho’s notebooks in 1619.