Looking again

We find ourselves agreeing with Antoine de Saint-Exupéry.

Some weeks ago our astronomer, pondering the awesome capabilities of his smartphone (well beyond anything he’s used so far), thought of a bit of software he had on his desktop computer years ago.  It’s called xearth, and shows a real-time graphic of where the sun is shining over the globe.  Compared to what is available now it’s quite primitive: land is green, sea is blue, and there is no attempt to represent the actual colors of desert or forest, much less clouds (which dominate the actual view of Earth from space).  But for its time it was advanced.  Indeed, he remembers wall-maps in technical headquarters buildings that did the same thing with projected lights, and getting the right curve of the sunrise-sunset line must have required some ingenuity back in the analog days.

Well, the program is not gone.  He found it and downloaded it to his phone.  The view is not the same as he remembers, probably because fitting in the phone’s screen and staying right-side-up does strange things to the Mercator projection.  Instead, he uses a new feature: xearth shows the orthographic (straight-on) view from an orbit you choose.  He decided on an orbit that takes an hour and a half (the time of low Earth orbit) and can pass straight overhead here, about 40 degrees north.  When he uses his phone for some other reason he checks his orbit.

It should not be surprising that half of the time he’s in night, also that half of the time he’s in the southern hemisphere (of course an orbit must go as far south as it does north); or that he spends a lot of time over the Pacific, and southern Africa appears often.  But it was.  The locations he’s in the habit of thinking about or referring to actually cover a rather small part of the Earth’s surface.

This is the same revelation expressed by Antoine de Saint-Exupéry in his book Terre des Hommes, translated into English as Wind, Sand and Stars.  He points out that travel by roads had given humans a very biased view of their planet, for roads only go to certain places, and even those that cross deserts go from oasis to oasis.  Earth seemed on the whole to be “merciful and fruitful.”  But as soon as airplanes started to travel the long routes, going directly from one place to another, they showed just how much of the planet was uninhabited and perhaps uninhabitable.

By following an orbit, our astronomer is taken out of his routine and faced with (say) nightfall in the ocean south of Madagascar, or a thin crescent Earth with only African lakes in sunlight, or the vast central Pacific at high noon.  It’s not that he didn’t know of these things.  He has in fact studied many of them in depth, for various reasons at various times.  But they had been, in a way, stored in the archives of his memory, and dust had collected on them.

It is good to dust off the archives now and then.