Monday, January 27, 2014

A Meta Portrait of Earth's Surface

The chart and data is certainly not new, but I find myself focusing on it in presentations and since it had previously been embedded in a graphic with ten other charts,  its meta coolness got diluted.  But I think about this map, like, alot, and I wanted to tell you why.  And why I call it a map.

Non-geographic data that can't help but arrange itself into a pixelated portrait of our planet.  What it is: Months on the left, time on top, roll-ups of pedestrian risk in the cells. What it really is: an emergent picture of the Earth's silhouette.

Geography Finds a Way
The data you see in this cell chart (or "heatmap", but since I'm a cartographer that term is sort-of taken) is non-geographic.  It shows the proportion of American traffic fatalities that involved pedestrians by time (left-to right is the time of day and night while the up-and-down splits up the months of the year).
Do you notice how strongly the band of elevated pedestrian risk bows the way it does?  That's because it is especially dangerous to walk at twilight (sun in your face, difficult lighting for object perception, more people walking about, all that).  But twilight is relative depending on the season, so you see the arc of sunset pushing out through summer months and back in for the winter months.  All because we live on a round thing flying through space.  The nature of that roundness is unintentionally revealed in this data.

An Echoed Silhouette of Earth
As we whiz around the sun, once a year, the tilt of our round Earth means that there is a lot of change in the amount and timing of sunlight each day (increasing as you move away from the poles) throughout each trip around.  Amazingly, or not so amazingly to the tougher nuts out there, is that the very roundness of Earth is echoed in the shape of the curve you see in this chart.  It's like what I would expect to see from a rough radio telescope signal of some distant planet, only it's our planet.  And the signal we see is an emergent reflection of our movements on its curved surface.
These traffic events happened in the United States.  But the curve would be the same for other Northern Hemisphere places, and it would bend the other way for places in the Southern Hemisphere.
Because we live on something that is dynamic, data of our lives often reveals the signal of that dynamic process -a roundabout meta image of Earth.  That's a map.

Life and Death
To lump data together and visualize it through different dimensions and isolate different rates can seem to dull the acuity of the very real tragedies that it represents.  While I know this is the data of death, the pixels that paint in this simple chart are sourced from pain and loss in aggregate volumes I can't comprehend.  However, one of the ironies of studying the data of death is that it is often almost perfectly correlated with the data of life and the distinction between the acts of living and the act of death dissolves.
Then, I start down the path of trying to illustrate the thread of life through ups and downs in geography to paint another, maybe more direct, portrait of Earth, which is our vaporous time on it.  And so it goes, the nature of our home to spring up in unexpected places, revealed by proxy in the data we collect about ourselves, nudging us into more questions with the benefit of perspective.

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