A Complementary Word for Proprioception
Trying to scale our understanding of our place in relation to our universe
While data visualisations are quite good at giving you an idea of the scale of things, doing so in relation to ourselves is a whole other endeavour. When it comes to making sense of our own bodies, we’re very good it: this is called proprioception. Proprioception is the cognitive awareness of where our body is in space without the need of looking at it (it relies mainly on muscle information), and it’s the sense through which we perceive our position and movement. The word comes from a Latin term meaning ‘unconscious perception of movement.’ Its purpose is allowing the body to control its position for optimal locomotion. So, if we are so good at relating to our own body’s scale and position, why do we fail when it comes to scaling it in respect to other bodies?
In autumn two years ago, my parents and I jumped on a train from London to Bridgwater-on-Taunton, a small town in Somerset, in the west of England. Like many other places in the country, it is crossed by a part of the huge canal network built in the 1800s. The day after arriving — in proper gray, rainy, English weather — we set out to walk a 22 km segment of the canal (my dad has a thing for canals, and for astronomy, which I inherited). Nothing particularly special about this segment, except that in 1997 it was populated with a scale model of the planets and star in our Solar System.
The Somerset Space Walk is a sculpture trail model of the Solar System. It features a model of the Sun and its planets in their proportionally-correct sizes and distances. Unusually for a solar system model, there are two sets of planets, so that the diameter of the orbits is represented as well. Pip Youngman, the head behind it, was well aware of the inadequacies of printed pictures of the Solar System — they depict only one scale, in most cases size, and leave out distance — and he designed the Somerset Space Walk as a way of challenging people’s perceptions of space and allowing them to experience the vastness of the Solar System. The model is built on a scale of 1:530,000,000 — meaning that one meter on the model equates to 530 kilometers. For reference, the Sun is 2.5 meters wide. Pip was well aware of our flawed perception:
‘Why are visitors surprised? After all we live on earth and we have eyes? We can see the Sun and Moon and the stars, so why should a model surprise us?’
Even though it’s set to scale, it’s still incredibly difficult, when doing the parcours, to get a real grasp of the Solar System’s dimensions — probably what stands out the most is how close Earth, Mars, and Venus are. When I stand next to Pluto (one centimeter wide on the Somerset Space Walk) and am so much larger than it, it is difficult to grasp its actual size. Moreover, retaining the memory of each planet’s size as you walk from one to the other is actually a quite difficult task. It seems as if you would need to be reminded of the complete set at every instance. And even when standing next to the Sun (taller than myself), with the faint memory of Pluto (that I could fit between my thumb and index fingers), my body deceives me. My brain deceives me. Just as with a sunrise: it’s near to impossible to feel that it’s the Earth moving and not the Sun. Properly interiorizing the scales of the planets in these types of models takes a lot of brain work.
The idea of a model to scale is attractive — human’s perception of spacetime, however, makes scaling exceptionally problematic. The pace at which you walk, your particular internal clock on that day, the stops made — all make it incredibly difficult to properly grasp how far apart each planet is from its neighbour. Nevertheless, humans have managed to build over sixty permanent scale models of the Solar System all around Earth—which at least speaks of a desire to accurately get a sense of this collection of bodies that we inhabit. The Sweden Solar System, for instance, is the largest permanent model, and uses a building as the Sun. The scale is 1:20 million, and its spans over the whole country.
Usually, when it comes to making sense of things — of getting the ‘full picture’ — humans rely heavily on their sense of sight, and on fitting those things within their frame of vision. Whilst this already is a fantasy (your actual perceptual span covers only about 6° of the 120° you supposedly ‘see’), it seems that whenever they cannot see the complete panorama, humans fail to understand it.
So, the Solar System is difficult to show correctly in models and visualisations. Why? Because the sizes of things are vastly different, and the distances they are apart from each other make these proportions in size negligible. The enormous ratio of interplanetary distances to planetary diameters makes constructing a scale model of the Solar System a challenging task. As one example of the difficulty, the distance between the Earth and the Sun is almost 12,000 times the diameter of the Earth. All of the images you have in your head of the Solar System are therefore wrong. These usually focus on the size variance (taking the opportunity to show each planet’s surface and colour) and are also flattened to a misleading bi-dimensionality. The distances of planets to the Sun are almost always neglected because of the vastness. Other levels of information are even more frequently omitted, such as taking into account the perihelion and aphelion (the nearest and farthest points of a body’s direct orbit around the Sun), as well as the y-position of orbits: planets don’t orbit perfectly in the same plane — instead, they fluctuate on different orbits in three dimensional space. Orreries, for instance, do more or less a better job at this — but they also fail at the distances part.
One astronomical unit (AU) is the distance from the Sun to the Earth. If I wanted to look at (almost) all the planets (still refusing to say ‘bye to Pluto), I would need to go out to about 30 AU to Neptune. That is not a problem, but then if I want to look at the size of the Sun, it is just 0.001 AU across. And the Earth is even smaller, at 0.0001 AU. Now, that is a problem. The distance from the Sun to Neptune is like five orders of magnitude greater than the scale of Earth. You can’t really show that on a sheet of paper. Distances are too big for both our senses and visualisation.
Designs that try to make sense of things in regards to ourselves abound. Pieces such as the earliest helio-centric models, the Eameses’ Powers of Ten clips, or a scale-model with moving, illuminated planets are all very illustrative. However, they almost completely rely on vision, and our bodily sense of scale gets lost in the picture.
Below is a series of visualisations to illustrate everything I’ve described about how the Solar System is usually depicted. Hopefully, these will help prove how difficult it is to put all of the relevant data into one piece, and why people are compelled to scale models that leave the A4 sheet of paper. (Note: I’m leaving out all measurement units as this is just to illustrate the factors at play).
Following the actual sequence of planets from the Sun:
While researching for this piece, the example that stuck with me — and perhaps the most reasonable for our screen-mediated present — was ‘If the moon were only one pixel’, by Josh Worth. This digital visualisation does just what the title says: it takes the smallest body in the system, our Moon, sets it at the smallest unit of measurement in the digital screen, the pixel, and takes things from there (the actual diameter of the Moon is 3,474.2 km). Venus is 4px, Earth 3px, Mars 2px, whilst Jupiter is 40px, and the Sun an impressive 400px. Distances are accurately represented, too: Venus to Sun is 31,000 pixels, and there are 1,699,735 pixels all the way to Pluto. As you scroll across (horizontal scrolling, for a change), you realise, almost with a hint of anxiety, how far apart things are from each other. Josh kindly fills those gaps with prompts to ease our anxiety (and impatience), but, as he points out, what you realise is that most of space is just space.
This model does a pretty good job at referencing scales. Asteroids, for example, don’t make the cut: they’re all too small to appear on the map (that is, under 1px). It references travel times — a 7-month spaceship trip to Mars or the 500-year, 75mph trip from Earth to (well, almost) Jupiter. Once you hit one billion kilometers travelled, you look at the bottom of the screen, and realise that in light minutes this is only 55 of them. Perhaps managing to travel at this speed would aid our understanding? Worth’s model makes it pretty clear why most maps of the Solar System aren’t drawn to scale: what is hard is not drawing the planets — it’s the empty space that is a problem. That’s when you realise that most visualisations leave out the most significant part: all the space. To wrap up with an even more frustrating fact: our Solar System doesn’t even actually finish with Pluto, at 39,5 AU (almost 40 times farther from the Sun than Earth is), but all across at something called the Oort Cloud, the outer edge of which is estimated to be at around 100,000 AU.
Do we need a new word — a variation for proprioception? A term that conveys how to merge two-dimensional data visualisation with three-dimensional experience? Would it be possible to incorporate some of what visualisations make so easy for the brain to understand (making things perceptible) into a bodily experience? In order to understand, humans have a need to reduce things down to something they can see or experience directly. Neurologically speaking, really they only deal with matter of a certain size, and with energy of a few select wavelengths. For everything else, it’s necessary to make up mental models and figure out if they match up to the tiny shreds of hard evidence that actually feel real. But all this empty space, these rotating spheres of a massive scale — that for sure is more than the human mind can conceive. Our maps and metaphors fail to do them justice.
Whether you more strongly feel the monumental significance of tiny things or the massive void between them depends on who you are, and how your brain chemistry is balanced at a particular moment. We walk around with miniature, emotional versions of the universe inside of us.
—Josh Worth
Elena is a graphic designer fascinated by languages and communication, and in a constant search to translate the world through typography and schematics. She believes that language, of any kind, is at the core of what we do and who we are.
