My favorite fun astronomy fact is that a transit like this (Venus, but still) is how we managed to figure out our distance to the Sun in the 1700s

The accuracy is incredible. They determined it to be 93,726,900 miles. This is within the bounds of our perihelion (≈91,000,000 miles) and aphelion (≈95,000,000 miles). Even more precise than Eratosthenes’ estimation of the size of the Earth