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Flickering Comet

  1. Nov 24, 2013 #1
    Hi folks,

    Had an idea for a science fiction story I'm writing, wondered if it would actually work in reality. Basically, if a comet's nucleus were comprised of concentric layers of ice and dust, would it produce a coma/tail in an on-and-off manner?

    Would it outgas and stop, outgas and stop as the materials exposed to the sun cycled?

    I am an astronomy buff, not an astronomer, and I am very aware of the difference. With that in mind, I thought I'd check before I put it to paper.
  2. jcsd
  3. Nov 24, 2013 #2


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    Once you have a layer of dust on the surface, what do you want to happen? Either it loses material or it does not, but not both at the same time.

    Even if that works, I don't see how it would lead to a "flickering" comet.

    How do you want to use the comet in the story? Maybe there is an easier way.
  4. Nov 24, 2013 #3
    I mean that the ices would burn off, creating a tail, then the dust would, extinguishing or diminishing the tail. It's constantly losing material, just different kinds of material.

    It's a device about establishing a character as an astronomer with layers.
  5. Nov 25, 2013 #4


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    What does that mean?

    Every material will reflect a part of the sunlight.

    If you want an object with periodic oscillations in brightness, rotation is a possible approach.
  6. Nov 25, 2013 #5

    Jonathan Scott

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    Here's my non-expert opinion...

    Even if the comet was somehow created in layers, I can't see any obvious way that the rate of loss of the volatile stuff could be synchronized between different parts of the surface, so different layers would be active at different locations on the surface.

    You might just about manage it if the only part which is losing material is some sort of band around a rotating section, although that's still quite implausible. It might work perhaps for a single loose "well" of layered material recently exposed, where the rest of the surface is relatively stable and inert.

    Dust and ice can both create visible tails anyway, but different materials behave in different ways under the pressure of sunlight, so you might get split tails or multiple tails.

    If it's fiction, you can invent some unlikely reason why it should work (perhaps involving heat pipe effects or similar which somehow have the effect of allowing each layer to be lost before the next one is started), but to be realistic I think anyone would normally consider this to be very surprising.
  7. Nov 25, 2013 #6
    Does it have to be a comet? Pulsars seem a better option.
    Or Quasars
    EDIT- The grainy pulsar pic might lead to bias so...
    Last edited: Nov 25, 2013
  8. Nov 26, 2013 #7


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    Nice pictures,Enigman!
  9. Nov 26, 2013 #8
    Very nice pictures!

    Thanks for the replies guys.
    The flickering isn't the hard bit, it was the layers. They're thematically important, so I'll work on a way to include them. A layered well is looking like the way to go. Pulsars are going to feature elsewhere though, errybody loves a good neutron star!
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