It’s hard to believe, but the last time we had the privilege to watch the transit of Venus, common mapping tools like Google Earth or Google Maps weren’t yet among us. It has been only seven years. The screenshot below shows how this very website looked back in November 2004:
The calculator, which helps you find the times of contact for your own observing spot, was already part of the website, but you had to enter your geographical coordinates by hand, and there was but little assistance in retrieving these. Yes, you were provided with a link to a list of place-names where you could see if yours was on it, but otherwise you had to search an atlas.
Today, our calculator makes use of modern internet mapping tools: it automatically detects your location and the transit data presented initially are computed for this position. But if you would like to know how the transit will look like at another place, you can just search for it, or drag the pointer around to the desired location. Thanks to a recent addition to Google Maps, were are now even able to give you a detailed weather forecast in the days leading up to the transit. And we continue to add new features to our calculator by exploiting the possibilities of these geospatial tools: for instance, we are now working on presenting a view of the transit in Street View.
These tools also change the way we can visualise the history of the transit. I created a Google Earth file, which has all the historical places where astronomers observered the transit of Venus in the past, pinpointed to the nearest 10 meters. The research that went into the creation of this list wasn’t possible without the ability to zoom into high resolution satellite images, or the capability to overlay old city maps unto today’s view of Earth from space.
These tools even change the way we will experience the actual transit ourselves. I recall that in 2004 I had to take great pains to get all the values required to contribute to the global experiment conducted by the IMCCE to derive the Sun’s distance from the combination of measurements of the exact moments of contact made all across the world: not only did I had to establish time accurately to the nearest second while in the middle of a sports field, I also needed to find my geographical coordinates. As the map with results shows, not everyone was able to do that last part, as some respondents seem to be located in the middle of the Atlantic Ocean. Next year, things will be quite different: time and geographical location can be submitted to our international database with just two taps on the touch screen of your phone, using our free phone app!
At the previous transit in 2004 this was all unthinkable of. What difference a few years can make, and what a blessing it is to live in this digital era!