Truth is stranger ...
by Hugo van der Sanden at 01:40 03/08/05 (Blogs::Hugo)
"The earth's second moon"
Those who watched it may remember an episode of QI in which Stephen Fry asked "how many moons does the earth have", and told the panel that there were two - the standard one, and a smaller more distant one called Cruithne.

I just found this article about it, and the truth is far stranger

  • it is an asteroid, about 5 km in diameter
  • it is in orbit around the sun
  • its orbit is very close to earth's, so from an earth's-eye view it is zig-zagging without going anywhere much
  • it's behind us, and catching up
  • it'll reach us around 2292 AD, coming within about 12 million km
  • when it gets here, it'll do a little dance around us, lose a bit of energy, and start falling back the other way round the orbit until it reaches us from the other side
  • then it'll dance again, gain some energy, and start back
  • and so, ad infinitum

Fascinating stuff,

Hugo

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