Pale blue dot

Some time on Friday evening (GMT), the defunct UARS satellite is going to fall to earth. Six tons of blistering, white-hot metal are going to splatter the lower atmosphere and the larger chunks will strike the surface at horrendous speeds.

NASA tells us that there’s only a one in 3,200 chance of any of us being hit, and since there are seven billion of us, I don’t think it’s going to be me.

But out of idle curiosity I thought I’d look up how much of the Earth’s surface is actually occupied by humans. I had to do it by subtraction, from various sources within that amazing oracle of truthiness that is the interwebnet.

I could dismiss 70% of the planet immediately, since everyone agrees that this much of it is ocean. How much is jungle or forest? About one third of the total surface of the earth, apparently. And Wikipedia tells me that one third of the land surface is desert. One third of the 30% that is not ocean works out as 10% of the total surface. I figure deserts don’t contain forests, and oceans contain neither (the polar cap isn’t included in the figure for deserts) so these are mutually exclusive areas. Whatever is left is habitable space.

Okay, so 100% – 70% – 33% – 10% = negative 13%. Hmm. Maybe I need to double-check the figures.

Either way, allowing a decent margin for error, I have to conclude that, at the most optimistic estimate, humans occupy roughly zero percent of the planet, give or take a little. Given that there are an awful lot of us anyway, this means we must be spread out like a spider’s web clinging to a beachball.

Well, maybe not a beachball. If Jupiter is a beachball, Earth is a marble, lost in an emptiness so huge that we’re a barely discernable, sizeless dot in the Jovian night sky. And the star we orbit is just one of two hundred billion in our galaxy alone, and there are about a hundred billion galaxies in the observable universe.

I lost my bike helmet yesterday. It doesn’t seem so important any more.

[Edit: whoops. Corrected the math. D minus.]


About stevegrand
I'm an independent AI and artificial life researcher, interested in oodles and oodles of things but especially the brain. And chocolate. I like chocolate too.

22 Responses to Pale blue dot

  1. You said “And Wikipedia tells me that one third of the land surface is desert. One third of the 70% that is not ocean works out as about a quarter of the total surface.” and I believe you meant “And Wikipedia tells me that one third of the land surface is desert. One third of the 30% that is not ocean works out as 10% of the total surface.” which would make your final calculation make slightly more sense.

    Still, the 70% ocean/33% forest bit is slightly puzzling. Are you sure those are considered fairly accurate figures? If so, then “forest” must surely include a great deal of inhabited space.

    I wonder what percent of the surface of the Earth is dense urban environment (that is, clearly in NO WAY forest).

    • stevegrand says:

      Yeah, I know. I corrected the math as soon as I saw it, but not soon enough! 🙂 And I just found another estimate of jungle coverage that claims one third of the LAND area, not the 1/3 of the total area claimed by my first source. So that leaves 10% of the planet as open, temperate land. Either way, it’s not much, which was the point I was trying to make. I wish I hadn’t started this now!

  2. Talking to Stones says:

    You illustrate an excellent point, Steve. Sometimes, it’s important to stop and re-focus, gain a different perspective on ourselves. We really are a very small part of the world, though at times our travails may loom large enough to seem to fill the universe in import. Some people don’t like realizing they aren’t really central to the operation of things, but I find the shift in perspective comforting. It means that, no matter how difficult or impending-doom-feeling things get in my life, they really aren’t that bad at all, in the greater scheme of things. It’s a bit like getting permission to step back, take a deep breath, and not worry quite so much. After all, there are far bigger issues out there. And most things usually work themselves out with a bit of time and a fresh perspective. This is one way to stop and get that perspective, to put things in context and reassess. Thanks for the pause. I needed it!

  3. Alon says:

    It’s great to read a post from you. I barely check here anymore.

    Make more. 🙂

    • stevegrand says:

      Heh! Thanks Alon – that cheered me up. I was in a kind of whimsical, flippant mood and felt a need to write something over breakfast, but I didn’t actually have anything to say. Most of my output goes into the Grandroids site at the moment (and virtually all of my mental energy into code). I’ll try to look out from my compiler once in a while! Don’t go!

  4. benjamin says:

    another way to calculate it is that we are curently 7 billion on earth. if we atribute 1 square meter (m^2) by men, the human race occupy 7 billion square meter, or 7000 km^2.

    the surface of earth is 510,072,000 km2, so we occupy physicaly (7.0/510072)*100 = 0.0013% of earth surface.

    so yeah, I confirm we occupy rougthly 0 per cent of the planet.

    if all human would hug together, we would fill almost completely the delaware (6,447km^2).

  5. Nekura says:

    I’d prefer to die by a falling satellite than toilet seat.

  6. Simon says:

    I seem to remember seeing a video by Carl Sagan about the “Pale Blue Dot” a few years ago. Your sentiments pretty much echos his.
    Its still there, search for pale blue dot on youtube.
    Best wishes Simon

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