Q: What was the big mystery that all these scientists were trying to solve?
A: In two words, it was "how far."
How far is the most important thing in our universe, the sun? And how far would you go to find that answer? Would you be willing to lay down your life? A host of scientists and explorers at this time did just that.
The other question is essential to the story: How far is the shore? That's the other question, the one that ship navigators could not answer. As a result, thousands of people died gruesome deaths at sea by shipwreck or being lost at sea.
These astronomers had invented an 18th-century GPS system that opened up the entire planet to seafaring nations. The voyages were the perfect testing grounds for this new technology.
The cool thing for the story is that to find the answer to both questions, you have to go to the ends of the earth. That sets the stage for an amazing adventure.
Q: How did this one event in the skies provide so much information?
A: Once you got to these far-flung locations, you could time – down to the second – the duration of how long it takes for Venus to pass over the sun. It was about six hours, but it varied depending on where you were on earth. They had to send people to Arctic locations and tropical locations to get as different a set of answers as you could get.
When you measure it down to the second, then you can answer these sorts of astronomical, scientific, and even philosophical questions.
Q: How did the astronomers time the transit so efficiently before they had modern clocks?
A: They would take these big, hulking pendulum clocks with them. Once you landed and set up shop, one of the things you get set up is the pendulum clock. Then you can get a very accurate reading, down to fractions of a second.
Q: Were they like grandfather clocks?
A: Grandfather clocks are quaint versions of the precision clocks.
Q: What drew you to this story?
A: Books talk about the science and all these voyages, yet the thing that I found most wanting in all these stories was just a simple answer to the question why. Why did all of these people risk their lives, why did kings and emperors write checks for the equivalents of millions of dollars to send these voyages halfway across the planet?