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Why don't we see the Geminids twice a year?

  1. Dec 16, 2012 #1
    We see the Geminids as a result of the fragments of the asteroid 3200 Phaethon colliding with the Earth's atmosphere. They are visible every year around December 13-16. As you can see in this NASA simulation (http://ssd.jpl.nasa.gov/sbdb.cgi?sstr=Phaethon;orb=1), we pass through the orbit of the asteroid twice every year (around Dec. 14 and Nov. 1). The circumstances seem to be the same on both dates, so why is it that I don't hear about the Geminids in early November?
     
  2. jcsd
  3. Dec 16, 2012 #2

    Bandersnatch

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    Rotate the orbit diagram to see that the ex-comet's orbit doesn't actually intersect with the Earth's orbit twice.
    In November the two orbits are not plane-aligned.
     
  4. Dec 16, 2012 #3
    We may cross Phaeton's orbit twice a year, but Phaeton itself isn't always where we cross it. So why should the Geminids be? Or are they spread out evenly over the whole orbit?
     
  5. Dec 16, 2012 #4
    Thank you Bandersnatch!
     
  6. Dec 16, 2012 #5

    Bandersnatch

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    Yeah they're spread out, but not evenly. The meteor count each year varies due to this.
    The meteors are just a bunch of debris following the same orbit that the asteroid from which it probably fell off.

    Also, I've just noticed that Phaeton3200 is not only not a comet, but it's also not-gone, so my previous post shouldn't read "ex-comet" but "asteroid".
     
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