2005-08-10

Orbiting Starship Visibility

Friday the 13th, 2029 will be an interesting day.

You see, back in 2004 a new asteroid was found, and its orbit was carefully calculated. As of a month ago, this asteroid had been given the formal number of 99942, and has the formal name of Apophis. As phrased most fabulously in the Wikipedia article, this is the first named asteroid with Earth impact solutions.

(SG-1 fans may now soil themselves at will.)

As it turns out, the asteroid isn't going to hit us . . . but it is going to come pretty damned close. As of May 18, it was estimated that Apophis would approach to within 30,000 kilometers of Earth on April 13, 2029 . . . way closer than the moon, and within geosynchronous orbital range (36,000km). The asteroid is 320m in diameter, and according to astronomers it will shine like a 3rd-mag star . . . in other words, it will be visible to the naked eye that night as it flies over Europe, Africa, and Asia.

And that's the point that got me thinking, since I'd never taken the time to do the math. What I mean is, we all know that the shuttle and the space station are visible in the sky. This never struck me as odd, though, since although they're tiny compared to sci-fi ships and stations, they're still just a couple of hundred kilometers up, in LEO. Obviously in the many Trek episodes where they're in orbit of some backwards civilization (i.e. something like where we are now), the starships would've been in a very high orbit and thus not observable. After all, Voyager is 340m, and the Enterprise-D was 640.

In any case, I always assumed that this orbit would be somewhere in the 40,000km range . . . i.e. transporter range. Well, it seems like that isn't enough. If a big dark asteroid at 30,000km is going to shine like a star, then what's a higher-albedo surface like a starship hull going to do?

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