population density

The Shadow of America, or, Yeah, I’ll Have to Work the Title Some More, Later (And Who Are We Kidding? I’m Never Getting Back to Fix That Title)

Alice Ristroph, via Democracy Journal:

On August 21, 2017, a total solar eclipse will arrive mid-morning on the coast of Oregon. The moon’s shadow will be about 70 miles wide, and it will race across the country faster than the speed of sound, exiting the eastern seaboard shortly before 3 p.m. local time. It has been dubbed the Great American Eclipse, and along most of its path, there live almost no black people.

Presumably, this is not explained by the implicit bias of the solar system. It is a matter of population density, and more specifically geographic variations in population density by race, for which the sun and the moon cannot be held responsible. Still, an eclipse chaser is always tempted to believe that the skies are relaying a message. At a moment of deep disagreement about the nation’s best path forward, here comes a giant round shadow, drawing a line either to cut the country in two or to unite it as one. Ancient peoples watched total eclipses with awe and often dread, seeing in the darkness omens of doom. The Great American Eclipse may or may not tell us anything about our future, but its peculiar path could remind us of something about our past—what it was we meant to be doing, and what we actually did along the way. And if it seems we need no reminding, consider this: We tend to backlight our history, and so run the risk of trying to recover a glory that never existed. When the light in August changes, watch carefully.


Ristroph, Alice. “Blackout”. Democracy Journal. 14 August 2017.

Not Politics (Orb Weaver Mix)

The scientists described their estimate of 35,176 spiders/m³ as “markedly conservative” and “representing a minimum volume” of spiders, by the way.

Question: do you measure spiders in Metric ShitTons? Or in Imperial ShitLoads?

Either way, it’s an awful lot of spiders.

Gwen Pearson

It is, actually, difficult to admit just how it is that spiders affect so many of us so irrationally. And it offers no useful comfort to point to the next person and note that they’re even worse about it. Then again, four acres of orb spinners just waiting for some unfortunate organism to blunder into their trap, amounting to a population estimated somewhere above one hundred seven million spiders, and a “markedly conservative” estimate of maximum population density at 35,176 spiders/m³.

Detail of Greene, et al. (2010). Table 1 shows Architectural Elements Used to Estimate Total Amount of Volumetric Webbing in Back River Sand Filtration Facility.Come on. Admit it. You’d be just as bad about it as the next person.

The 2010 technical paper is available, for those so inclined, either through Pearson’s blog for Wired.com, or in our own archives.


Pearson, Gwen. “4-Acre Spider Web Engulfs Building”. Charismatic Minifauna. 31 October 2014.

Greene, Albert et al. “An Immense Concentration of Orb-Weaving Spiders With Communal Webbing in a Man-Made Structural Habitat (Arachnida: Araneae: Tetragnathidae, Araneidae)”. American Entomologist, 56 (3). 2010.