Giovanni Schiaparelli's map of Mars showing the imaginary canals (image from wikipedia)
Maps, Maps, Everywhere! That was the theme at this year's inaugural PSERF meeting at UWO given by Phil Stooke. By the way, PSERF stands for Planetary Science & Exploration Research Forum, and truth be told, I'm writing that down here not only for your benefit, but also so I can refer back later and remember what it stands for. To say that the discussions are eclectic is a bit of an understatement. This was my third meeting and so far we've had a presentation on Space Weapons, a report by CPSX's own Bhairavi Shankar on an impact cratering short course, and now a discussion of early terrestrial cartography.
Still for those of us interested in space exploration, maps provide a useful example. In its purest sense, exploration is about "filling in the gaps." Maps also give us a good way to examine the state of knowledge at any one time. For instance, if you look between the "Cantino Planisphere" (a world map from around 1500) and compare it to "The New and Correct Map of The World" from 1700 (you can find both in the slides linked to this article) you'll see how the age of maritime exploration managed to give us a better picture of our own planet.
Sometimes the most interesting places to look on a map are inside of blank areas. This is true because of the human tendency to project onto these areas. It might be something mythological, like the locations of the garden of eden, where moses parted the red sea, or the headwaters of the nile all popular in many T and O maps from medieval europe, as discussed today. Or it might be something at the limits of our abilities that we can talk ourselves into believing we have seen like the "canali" that the famed italian observer Schiaparelli claimed to have seen on Mars.
Interestingly, whether you guessed right or wrong has a lot to do with your ultimate disposition in History. Jose Comas Sola made equally suspect early observations on Titan at around the same time as Schiaparelli in which he claimed to be able to see limb darkening - indicative of an atmosphere - and clouds. His claims are seen as being prescient, but, in truth, the features he claimed to be able to resolve were no larger than Schiaparelli's canali.
Sometimes we can fool ourselves that we're making scientific inferences. So we grasp at theory to fill in what we don't see. Only recently have we begun to move past the stage in the outer solar system in which the brightness of an object leads directly to claims of (1) albedo, (2) size, (3) mass and (4) formation history (in that order).
In today's talk, Dr. Stooke focused on showing us many of the older maps of the world, typically of the T and O persuasion that existed from Babylonian times up until just before the Cantino Planisphere. (as an interesting aside, these are typically oriented with East shown at the tops of such maps leading to the term "Orient" for the lands of the east) One of his most interesting points was that many map-mapkers showed Africa as having a forked southern peninsula and a large island in the atlantic ocean. He posited that this could have resulted from an old belief from the days of Aristotle (and later Plutarch) that the moon was a mirror that reflected an image of the Earth.
To get an idea of what Phil meant, take a look at an image of the moon (shown below from Clementine Data). If you consider it alongside a flipped early map, you find that the mare (dark areas) on the right match up roughly with the location of Africa. These appear to fork as you look towards the bottom of the image and there is another large maria to the right of the forks, in what would have been the atlantic ocean. Both these features are depicted on maps of this periods, and the imaginary island even has an inscription, sometimes, about being the location where souls travel after death (a reference to the moon).
Composite image of the moon using a mosaic of Clementine data. Note on the right hand side two large maria, one on top of the other (serenity and tranquility), with two smaller maria below and to the right (nectar and fecundity). This feature was thought to indicate a forked peninsula for Africa in the days when many thought the moon to be a mirror. The aptly-named sea of crises to the far right across from tranquility was thought to represent an imaginary island in the atlantic.
The idea of the moon as a mirror persisted and Leonardo DaVinci found himself mounting a vigorous debunking. However, the idea didn't ultimately die off until the arrival of Galileo's telescope, which showed the moon to be a world in its own right.
When you get right down to it, what exists in those blank areas is all about us. We can project our theories, our hopes, fears and mythology there. Or we can resolve to go out and see for ourselves.