back to article Comet Holmes and the case of the Disappearing Tail

The Web is abuzz about Comet Holmes. Comet 17P/Holmes had been expected to make just another routine ultra low visibility departure from perihelion passage this year. But in a record for a comet, it unexpectedly brightened by a factor of around a million on October 24, making it more reminiscent of a stellar nova explosion. " …


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  1. Anton Ivanov

    Everybody got it wrong

    Here is what really happened

    Dialogue on the Bridge:

    Captain: Why is the main drive on while the Earthlings can still see us on you mindless tentaclebrain twats?

    First Officer: Your have ordered it yesterday while legless on ammonia vapour your honour.

    Captain: Well, we might as well make full use of it. Punch it. Maximum burn.

  2. Ross Nixon

    The Electric Universe?

    There is some theory called "The Electric Universe" which is supposedly wacky pseudoscience. Maybe there is a grain of truth in it?

    There certainly is a large body of very shaky cosmology trying to present itself as largely proven fact - the Big bang Theory, for example.

  3. Andrew Bush

    Expansion / contraction

    I'm no astro-expert, but even in the near absolute zero of space wouldn't things still expand and contract as they heat and cool down. If a comet is an icy rockball or a rocky iceball wouldn't the constituent components expand and contract at different rates. Could this cause an object to crack? With water expanding as it cools and rocks contracting as they cool wouldn't moving further from the Sun create the right (cooling) conditions?

    All you experts can shoot me down in flames if you like, but its just a thought.

  4. AngrySup

    Why Doesn't it have a tail?


    The countdown has begun.

  5. Tawakalna
    Paris Hilton

    @Andrew Bush..

    that's exactly what I thought! comets are balls of dirty rock, soil, ice, and gas, all jumbled up together, why shouldn't they expand and contract at different rates as they go round the Sun? Stands to reason that there'd be hairline cracks on the way out and the way in that would get worse as the temperature changed.

    I'm just not getting this plasma/electricity part. Anyone care to explain?

    tbere's no icon for "I may be a thickie but..." so I'll use Paris Hilton again.

  6. Anonymous Coward
    Dead Vulture

    That comet of 1680..

    Apparently made perihel at 0.00622 Astronomical Units ~ 10^6 kilometers.

    So there's a 0 missing at the 100'000 km mentioned.

    Nothing passes the Sun at 100'000 km and lives - except Captain Future!

  7. Chris G

    Shoot em up!

    Clearly this is just another cover up from Roswell. G Dubya's cosmic flyboys are just brushing up their interplanetary top gun skills in their stolen alien spacecraft. What you are all calling comets are in reality just big cosmic clay pigeons.

    In answer to the question `What is a comet?´ It is an airliner manufactured by De Havilland in the sixties, the first jet powered airliner to go into service and in my opinion much better looking than most of the modern wide bodied cattle trucks everyone flies in now.

  8. Lexx Greatrex
    Thumb Up

    Nicely written article Reg :)

    Plus: burst my colon laughing @Anton and @AngrySup

  9. lglethal Silver badge
    Thumb Down

    @ Ross Nixon

    Actually, the Big Bang is pretty much a proven theory. The expected/calculated results of the big bang have been proven by observation going back to within the first few seconds after the big bang. True the exact mechanisms of the moment of the Big Bang have yet to be proven but to claim that the Big Bang is shaky science is a tad ridiculous...

  10. dave everett

    Comet Holmes Website

    There is a new website dedicated to Comet Holmes:

    There are links, news, location, and more....

  11. Charles Manning

    Big bang isn't proven

    In science nothing is ever proven. There is no such thing as "proof by observation/demonstration". All you can say is that a theory is consistent with observations/demonstrations, allowing one to be reasonably confident that you're on solid ground.

    And no, I'm not being anti-Big Bang. The same applies to gravity et al. In theory gravity applies to all objects with mass. The observation that brick released from hand falls on toe does not prove gravity, it merely demonstrates it. Perhaps there is some mass out there that is immune to gravity and the reason we cannot find it (and why it does not amass into planets) is because it needs gravity to form into planets and we use gravity to detect mass.

    The Big Bang is just a model. A model (a parable for people in white coats) draws together various observations and theories and makes them seem consistent (I say seems because I have not personally checked out Big Bang and I expect there are some out-of-focus bits that need hand waving to explain).

    Before we get all uppity and defensive of science, it is worth noting that science goes through phases of making up models, finding a lot of support for those models, then finding a weak spot and watching those models crumble.

    For example, up to approx the 1960s, plate teutonics was rubbished by the scieeeentists of the day as a very stupid idea, yet we (mostly) accept plate teutonics now (40-odd years later) and look back at the pre-teutonic folk as if they were flat-earthers.

    It is really naive to think that many of our pet theories of today won't get trashed within the next 50-odd years. To think otherwise would suggest we've reached as far as science can - that would be a sad thought.

  12. Ross Nixon

    Big Bang in trouble

    The Big Bang is a hypothesis on trouble. and

    for something newer

  13. JeffyPooh

    Locating comet 17P Holmes easily

    Not everyone knows the constellation Perseus. But Cassiopeia is the famous W-shaped constellation that almost everyone knows. Find the 2nd stroke in the W and follow it down (down-stroke) about 5 stroke lengths and you'll be fairly close to a bright star within Perseus. The comet is right there. In fact, tonight that bright star (Mirfak?, a-Perseus?) was within the area covered by the comet.

    Although 17P Holmes is sort-of visible to the naked eye, it is much better using binoculars. Once you find it, you see that it looks like a big fuzzy snowball.

    Using this method it is very quick and easy to find 17P Holmes.

  14. Anonymous Coward
    Anonymous Coward

    RE: That comet of 1680..

    > Nothing passes the Sun at 100'000 km and lives - except Captain Future!

    dont forget Doctor Who and Marther jones, they got very close to the sun ( well a Sun :) ) and they lived :)

  15. Stuart Van Onselen
    Thumb Up

    @Andrew Bush & @Tawakalna

    Your theory is the same one believed by astronomers for years - Differential expansion (plus tidal effects (plus outgassing)) was the cause.

    The problem came in when other astronomers noted that most comets where breaking up miles away, err, many Astronomical Units away from the Sun. At that distance, temperature changes very slowly as the comet moves, and all the components have had many years to settle into thermal equilibrium.

    Which means that differential expansion (plus tidal effects (plus outgassing)) doesn't explain squat when it comes to *most* comets. To which most astronomers replied "WTF?!?!?", albeit in more academically appropriate language. :-)

  16. TeeCee Gold badge


    Do you mean "tectonics" by any chance?

    I must admit though, the idea of geological structures of continental scale stomping around in jackboots wearing uniforms covered in lots of shiny buttons surmounted with pointy helmets and barking harsh, gutteral orders at anyone within earshot is quite surrealistically appealing. Less likely to earn a permanent place in the pantheon of accepted scientific theory I'd have thought though.

  17. Andrew Bolton

    Creationists get everywhere, don't they?

    Nice one, Mr Ross Nixon - slip in a godbotherer article link. Bit of a giveaway when the author has "To be a Disciple of Christ" in his list of other articles. Makes it somewhat hard to take anything he writes seriously.

    Now, where's the icon for a beardy bloke with a big red cross through it...?

    By the way, I hope everybody is aware that today is International Slap a Creationist Day? If you know a creationist, you must give them a slap, accompanied by the statement - "Oy, NO!!!". If they are one of those fundamentalist creationists that think the earth is ACTUALLY 6000 years old, they MUST offer you the other cheek to slap as well. Take full advantage.


  18. Gianni Straniero

    @Charles Manning: "Plate Teutonics"

    Ve have vays of making ze continents move about ven floating on ze mantle!

  19. Anonymous Coward
    Anonymous Coward

    If it's exploded or split why can't it be as simple as....

    ....ikt just hit something too small and dark for us to see? People always look for the complicated when a simple knock-for-knock would account for the whole thing.


  20. Anonymous Coward

    @Ross Nixon

    I would guess that most El Reg readers are smart enough to read the referenced articles and troll the authors' background. The real question is, what is Ross Nixon doing on this website?

  21. Phil Hill

    Electric Universe - Seems Like Common Sense

    I've recently read some stuff about the Electric Universe in an unbiased way, and it just seems to make more sense and explain the observations better than having to invent invisible, undetectable, untestable dark matter, dark energy, black holes and other mysterious stuff, apparently to protect those with long astronomical careers built on this flakey stuff.

  22. Joe Stalin

    @Big bang isn't proven

    Second paragraph.

    There is in thoery a element with no mass. I think CERN did some experiment a few years ago and the results hinted at it. The Universty I worked for at the time had one of there guys in on the experiment and we had the story (possible new scientist) photocopied and pinned on the physics dept notice boards.

  23. Ian Tresman

    More IEEE information

    Comets may have up to three tails, such as the well-known three tails of Comet Hale-Bopp. These are (1) the neutral sodium tail, (2) the blueish ion tail (sometimes called the plasma tail), and (3) dust tail.

    The interaction of the ions with the interplanetary magnetic fields will produce electric currents and magnetic fields within the tails.W.-H. Ip and D. A. Mendis writing in Icarus (vol. 29, Sept. 1976, p. 147-151) estimated that "cross-tail currents as large as 1 billion A may result".

    The contents of the August 2007 IEEE 7th Special Issue on Space and Cosmic Plasma (mentioned in the article) can be seen on their Web site at:

  24. JeffyPooh

    Oh - my - gawd...

    I was looking at 17P Holmes last night. I took a picture and analyzed it on my laptop. It's not a comet. It looks like a doily; an E8 doily. Oh my gawd, Garrett Lisi is right - THE UNIVERSE IS A DOILY !!!!!! ARGHHHHHHH!!!!!!

    (then follow the link pointed by the red arrow)

  25. Alan Jenney

    Incoming giant jellyfish

    When observed through simple binoculars, there is considerably more brightness around a central area as well as the outer glow, looking like a fried egg.

    Because of the position of the Earth and Sun relative to 17P/Holmes, when observed at night the tails of the comet appear behind the bright centre of the comet. These streamers have been quite noticeable as they have come and gone. Looking through a telescope, the impression you get is of a central complex, colourful halo with the tails in the background. Just as if there was a 100-mile-wide jellyfish heading for Earth. Wait a minute...(!)

  26. Andy Worth

    So is it the case...

    ...that no-one actually truly knows the reason why this happened and they're in fact just guessing? Amazing how little we actually know about the things around us really and how much is based on "best guess". Always makes for a nice surprise from time to time :)

  27. Anonymous Coward
    Anonymous Coward

    extra terrestial

    maybe the comet was heading past/towards an alien planet who decided to try out it's firepower/experiment on it

  28. Rick Easton

    @Alan Jenney

    That's no jellyfish, thats the FSM.

    Quick! everyone on their knees - start praying...

  29. Steve

    I for one

    welcome our new comet like overlords.

  30. This post has been deleted by its author

  31. Morely Dotes

    @ Charles

    "For example, up to approx the 1960s, plate teutonics was rubbished by the scieeeentists of the day as a very stupid idea, yet we (mostly) accept plate teutonics now (40-odd years later) and look back at the pre-teutonic folk as if they were flat-earthers"

    Just please don't mention the war during dinner!

    Yes, the long black one, right next to John Cleese's.

  32. Anonymous Coward
    Thumb Down

    Better than the abysmal Dark Matter article...

    That was better than the Dark Matter post; it had links and I didn't have to resort to wikipedia to learn about some crackpot theory. But I still felt I needed to read the sources to get a handle on the debate - all you'd done is point me at the issues, rather than informed me about them.

    And you're pretty disingenuous in your use of Jewitt – quoting the one sentence of "hedging" that happen to support your ideas. Why didn't you mention that comets are spinning so fast that they're on the verge of flying apart? (BTW folks it's this, not fatigue, that is the likely cause of cometary disintegration. Comets are so big (1-100km) that they'd remain gravitationaly bound even if the sun cracked them like a cold glass in hot water.)

    I haven't had time to read the IEEE stuff yet, and probably won't. My loss. But it'd be nice if I didn't have to.

  33. Luther Blissett

    Universe now has a name

    JeffyPooh: >> I was looking at 17P Holmes last night. I took a picture and analyzed it on my laptop. It's not a comet. It looks like a doily; an E8 doily. Oh my gawd, Garrett Lisi is right - THE UNIVERSE IS A DOILY !!!!!! ARGHHHHHHH!!!!!!

    In which case, it's name is Centrino.

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