An astronomical unit (AU) is exactly 149,597,870,700 meters (92,955,807 miles or 149,597,871 kilometers), according to the International Astronomical Union (IAU). This is roughly the average ...

That threw the post-1769 figure for the Astronomical Unit off by a few percent from the correct answer. Still not bad, actually. And how did the transit of Venus give us the distances to the stars?

After hundreds of years of approximating the distance between the Earth and Sun, the Astronomical Unit was recently redefined as a set value rather than a mathematical equation.

If you guessed the astronomical unit, you are correct. The au — the rough distance between the Earth and the Sun — was previously determined by a ...