In 1961, Frank Drake helped organise the first Search for Extraterrestrial Intelligence (SETI) conference. In preparation for his speech, he came up with the Drake Equation, which effectively multiplies a whole lot of unknown probabilities together to come up with a figure which may or may not tell us how many real live aliens there might be out there trying to communicate with us.

Drake’s Equation is little more than an interesting thought experiment, since every single variable is a SWAG. Still, people use it to come up with a figure that motivates them to aid the search. Nothing wrong with that.

But even if Drake’s Equation convinces you that there are many many civilisations out there, there’s reason to believe that the Earth is unique, or at least very rare, in one way. From where we stand, the sun and the moon both occupy about 30 arc seconds, or to put it differently, the sun is 400 times bigger than the moon and also 400 times further away.

Where the unique becomes sublime is when we have a total eclipse of the sun. If the moon were bigger, we wouldn’t see a halo. If the moon were smaller, it wouldn’t be a total eclipse.

Which is why Iain Banks, in his novel Transition, suggests that instead of watching the great American eclipse of 2017, you should rather be looking around. Many of the spectators might have hitch hiked a number of lightyears to observe the phenomenon.

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