How did scientists determine how fast earth's orbit is around the sun?

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How did scientists determine how fast earth's orbit is around the sun?

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Answer 1 · 2016-02-22T15:52:48

The orbital speed of the Earth is easy to calculate using geometry - we can find the circumference (distance) and divide it by a year (time)

Explanation:

The Earth completes one full orbit, $360^{\circ}$ $360^@$ , in one year, which is 365.256 days, or exactly 31,556,926 seconds.

The Earth's orbit is slightly elliptical, but is pretty close to circular. The mean (semi-major) distance from the sun to Earth is 149.6 million km. Remembering our geometry a circle with a radius of 149.6 million km is:

$c = 2 π r$ $c=2 pi r$
$c = 2 \cdot π \cdot 149600000 k m$ $c=2*pi*149600000 km$
$c = 939964522 k m$ $c= 939964522 km$
or
940 million km.

the orbital speed can be calculated using:
$v = \frac{d}{t}$ $v=d/t$
$v = \frac{940000000 k m}{31556926 s}$ $v=(940000000km)/(31556926s)$
$v = 29.79 \frac{k m}{s}$ $v=29.79 (km)/s$

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How did scientists determine how fast earth's orbit is around the sun?

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