Our unique light footprint

Nighttime portrait of Toronto, from orbit

Toronto light footprint, 24 December 2010 @ 1:35:40 am [International Space Station (Electronic Still Camera, Mission 26, image 12469)]

Toronto light footprint, 24 December 2010 @ 1:35:40 am [International Space Station (Electronic Still Camera, Mission 26, image 12469)]

This was shot early on the 24th of December at 1:35:40a, according to the International Space Station’s image metadata.

Few other ways demonstrate so well the excess lighting we generate municipally that is wasted and lost for, well, nothing. Not nearly this much light makes a city safe and, if anything, possibly less so (the South Chicago and San Antonio case studies come to mind).

To be honest, I am less concerned by the “light pollution” problem that is the singular, overarching foe of astronomers — which I have argued is too narrow, too limiting in scope, and impossible to summon an immediate political response to drive public policy change and capital improvements. Rather, I frame this as a nocturnal ecosystem problem: artificial lighting at night negatively impacts the health of nocturnal life up and down the food chain. I frame it as a public health problem, with increasing likelihood from peer-reviewed epidemiological research finding a strong correlation between urban lighting at night and a broad, upward trend in certain carcinogenic activities at a macro scale (namely, breast and prostate cancer). I frame it as an urban economics problem, as both capital cost forecasting for lighting infrastructure and operational costs of indiscriminate, poorly planned outdoor lighting schemes really don’t help the city wisely manage its costs. And I frame it as a criminological problem — where unfocussed, indiscriminate street illumination actually appears to render nocturnal spaces as less safe for individuals, as overlighting actually makes it harder for the low-light capability of our eyes to properly see everything as well.

Also, if you look extremely closely at full size, you can also make out a few nifty features.

  1. The history of Toronto through its street lighting. Aside from the obvious growth axis along Yonge Street up into Richmond Hill and beyond, you can actually see that the old City of Toronto outline is distinct from the rest of Toronto. This is because the old Toronto used a different streetlight bulb — first, mercury vapour, then replaced over time by bluer metal-halide. What is fascinating about every night portrait of city light footprints is that you can make out its historical and morphological features in ways you cannot with a daylight photo.
  2. The concessions of original property lot lines, post-John Graves Simcoe, are easily seen. Moving up (north) from the lake, the concessions, or streets every 2km apart — Queen, Bloor, St. Clair, Eglinton, Lawrence, and so on — are the brightest east-west in the grid, while the narrower 200m spacing between north-south streets (like Yonge, Bay, Avenue, St. George, and so on) are also easily seen.
  3. The purple light seen in the western area of downtown (that very bright cluster)? It’s the Skydome. The purple flood lighting is characteristic of the Rogers era of ownership.
  4. The blurriness towards Mississauga is not cloud cover, but actually the particular portal window the International Space Station photographer was using. This blurry feature appears in many of the ISS’s photos, of which all are added to their public database. But you can still make out a semi-rectangle of darkness. Those are the runways of Pearson Airport. Just a bit to its east, and with a line oriented in a north-northwest/south southeast configuration is the old CFB Downsview runway. Airports are generally the darkest built features inside a city. They need to be in order for air traffic controllers to make visual confirmations and for pilots to safely land aircraft. Behind airports, cemeteries are the other dark built feature. Mount Pleasant Cemetery, just east of Yonge and north of St. Clair East, are seen as two dark rectangles. Interestingly, hospitals make up some of the brightest built features.
  5. Another bright feature found in just about every major city are freight rail yards. For cities like Toronto and Montréal, the yards tend to use the orange, high-pressure sodium (HPS) lighting. If you look again at CFB Downsview, you will notice to its southeast periphery a glob of bright orange. These are the rail yards you can see from the subway between Yorkdale and Downsview station. There is also another rail yard near Royal York and the Lakeshore. Montréal sort of wins in the overlighting game: its Taschereau Yard — aka, “Spaghetti Junction” — drowns out everything else I’ve ever seen in Canada (look to the right — east — of the dark hole of Dorval Airport and find a long, bright line).
  6. In the unlit rural areas, as well as over parts of Lake Ontario, the land doesn’t look black, but a dark grey. That’s because on the night this shot was made, a waning gibbous moon was almost directly overhead. It was about 75–80 percent full and almost at its “lunar noon.” This grey hue is snow and ice cover reflecting moonlight. Had this been shot on the night of December 20th–21st, just before or after the lunar eclipse, the ground cover would have been about three times as bright. The Leslie Street Spit is visible here because of such bright moonlight.
  7. The east west arterial which looks like a string of beads is the 401 407 Express Toll Route [ed. correction: the 401 is actually less visible as a curved arterial further south, running alongside Downsview at one point and bending just south of Pearson; its curve is visible because it is generally not in line with the concession arterial grid]. The “beads” are those super-tall road lighting luminaires which project onto most of the expressway.
  8. The darkish blotches pockmarking the city light grid are the city’s ravines and valleys.

What makes this light footprint photo, only the second known photo of Toronto at night from the ISS (the first, from 2008, can be seen below) particularly special to me — aside from delivering the highest resolution and best quality yet of Toronto at night — is that I was actually outside around that very moment, wrapping up a photo shoot (using Kodachrome film in the final five days one could do so) at Casa Loma. Given my own research on Kodachrome Toronto: 1935–2010 and my separate research on photopollution, there’s something a bit fitting about these interests converging together as one (digital) camera looked down, and the other (Kodachrome film) camera looked up.

It’s kind of astounding.

Toronto light footprint, 20 January 2008 [photo: International Space Station (Electronic Still Camera, Mission 16, image 24232)]

Toronto light footprint, 20 January 2008 [photo: International Space Station (Electronic Still Camera, Mission 16, image 24232)]


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