How to determine the diameter of Earth?

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Measuring the Earth's diameter cannot be done directly with rulers; instead, methods like those used by Eratosthenes and the Great Arc are suggested for estimation. The discussion highlights that similar techniques can be applied to other celestial bodies, although the methods differ. For planets, diameter estimation can be achieved through occultation, where the timing of a radio signal from an orbiting probe is analyzed as it passes behind the planet. Asteroids are measured using stellar occultation, where observers note the timing of a star's light being blocked by the asteroid. This approach is analogous to observing solar eclipses, where the duration of the eclipse varies based on the observer's location.
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We cannot measure the diameter of Earth inch by inch using rulers, and must somehow estimate the distance on Earth, Does anyone have any suggestions on what approach they use to measure the diameter of Earth? and how does this approach apply to measure the diameter of other planets?
Thanks in advance for any suggestions
 
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Google Eratosthenes, then google 'The Great Arc' and perhaps 'The Prime Meridian through Paris'.
 
And after that, maybe also google Struve Geodetic Arc
 
how does this approach apply to measure the diameter of other planets?

it doesn't.
 
A planet's diameter may be estimated by occultation, such as studying the cut-off time of a radio signal from an orbiting probe as it swings behind the planet.

Asteroids have been 'sized' by stellar occultation, where many observers watch for a star's cut-off time. From their position on Earth, the asteroid does or doesn't eclipse a background star.
http://www.physorg.com/news/2011-10-faraway-eris-pluto-twin-dwarf.html

Analogy is a solar eclipse, where folk off the centre-line see shorter and shorter eclipses...
 
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