How did Astronomers use the transit of Venus across the Sun to calculate the distance between the Sun and Earth back in the 17th century?
In: Mathematics
By recording exactly the moments that Venus “touched” the sun, or was completely within the sun’s disc. These times would be slightly different for different places, because of parallax.
They were observing Venus from different places on earth and the different timings gave the distance to Venus via trigonometry and the fact that we knew the size of the earth. We also knew the proportions of the whole solar system, so knowing the distance to Venus told us the size of the whole solar system, including the earth’s distance from the sun. It actually didn’t work as well as hoped since it’s hard to see the exact instant when the edge of Venus touches the edge of the sun; the sun is so bright.
You say 17th century but Cook’s voyage was in 1769 … in the 18th century.
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