back to article Massive rugby ball-shaped planet emerges from scrum of space 'scope sightings

Just over 1,500 light-years away in the constellation of Hercules there’s a rugby ball-shaped exoplanet orbiting a star. It’s the first time astronomers have been able to detect such an unusual shape of an alien world. Most planets are more or less spherical due to gravitational forces that pull matter equally in from all …

  1. Christoph

    Jinx?

    They've found Larry Niven's rugby-ball shaped planet Jinx.

    1. Paul Herber Silver badge

      Re: Jinx?

      and two satellites around Jinx called Pixie and Dixie.

  2. Phil O'Sophical Silver badge

    Or rings?

    Wouldn't a ringed planet like Saturn also look that shape when seen side-on from a great distance?

    1. KittenHuffer Silver badge

      Re: Or rings?

      Rings would never survive around a planet that close to a star. They would be stripped off in very short order.

      1. ThatOne Silver badge

        Re: Or rings?

        To put it differently, you don't put your jewelry on display in such a neighborhood...

      2. ravenviz Silver badge

        Re: Or rings?

        How short is short? This observation could be within any ring lifetime.

        Other possibilities could be a recent body break up due to tidal forces blocking light asymmetrically, which could also be a reason for the orbital disturbance, i.e. some sort of close pass in a chaotic gravitational environment.

        1. KittenHuffer Silver badge

          Re: Or rings?

          Rings don't form quickly. When the body they come from breaks up it takes time for the rubble to spread out in an orbit to the point where you can call it a ring. If that happened in this scenario then the gravity of the star would be disruptive enough that the ring would never have time to form in the first place.

          Plus the amount of sunlight the ring would block would be a fraction of the amount a bulge would block. This would change the data that was observed such that the extra sunlight blocked would probably have been hidden amongst the noise of the signal.

    2. Cuddles

      Re: Or rings?

      No. These observations are basically looking at the intensity of light coming from the star, and spotting how the intensity drops when a planet passes in front of it. Planetary rings are extremely diffuse collections of dust and small objects, and therefore won't block anywhere near as much light as the body of a planet. Seeing planets in this way has only become possible in the last couple of decades, and this is the first time someone has managed to get some idea of the shape of such a planet. Measuring things like rings and moons will need a few orders of magnitude more sensitivty, and so is likely at least a couple more decades away, if it becomes possible at all.

  3. KittenHuffer Silver badge
    Boffin

    Just a suggestion

    The Moon is moving farther away from the Earth because it is tidally locked, and is stealing rotational energy from the Earth (via tides) to move to higher orbits.

    Even though this planet is a gas giant its rotaion may have been slowed to almost nothing by the tidal forces of the star, and is now stealing rotational energy from the star to move away from it.

    1. KarMann Silver badge
      Boffin

      Re: Just a suggestion

      The planet's rotation doesn't factor into it for those purposes; what matters is the parent body's rotation, i.e. the star's in this case. Given that the planet orbits in less than a day per the article, I'd be slightly surprised if the star rotated faster than that, as would be required for it to be enlarging/lengthening the planet's orbit (cf. the Earth rotates in rather less than a month, which is why it can boost the Moon's orbit around it), but I'm basing that on a sample size of one, knowing that the Sun rotates in about 26 days (depending on latitude).

      I've added a data point; remembering Vega being fairly remarkable in its rotation, I looked up that that one does rotate in 12.5 hours, but its rotation is quite egregious, so it's possible but unlikely that this star does rotate fast enough for that to happen. Further checking on Wikipedia suggests that the planet's more precise orbital period is 0.926 days, and if I've done my sums right, the star's rotation period is just under a week, so that wouldn't work for an explanation. But it's definitely worth considering before eliminating it, indeed.

      1. Jonathan Richards 1

        Say what?

        > the Earth rotates in rather less than a month

        Well, the moon rotates around the earth in 27.32... days relative to the fixed stars: this is the sidereal month. I don't think the Earth rotates around anything in those timeframes (unless you're using a selenogical frame of reference, in which case, yuk!)

        1. KarMann Silver badge

          Re: Say what?

          Rotates, not revolves; i.e., in about a day, 24 hours even or, more applicably for this purpose, 23 hours 56 minute 4 seconds. I meant 'rather less' in the slightly sarcastic sense of 'much less'.

  4. lglethal Silver badge
    Boffin

    I'm just going to say it...

    Science is awesome. Not only does the universe throw up complete curve balls (sorry rugby balls), but we are able to see it and understand it.

    Awesome!

  5. Disgusted Of Tunbridge Wells Silver badge
    Pint

    This is where Guinness came from. We must go there.

    1. Disgusted Of Tunbridge Wells Silver badge
      Facepalm

      On second thought, if it's an exoplanet it'll be Guinness Extra Cold.

      Nevermind.

      1. KarMann Silver badge
        Pint

        I don't quite see how that follows; exoplanets aren't necessarily, or even often, cold. In this case, it seems to be about 2,200℃, which should be warm enough, even a bit above room temperature. The night side, only about 1,600℃, though.

        1. Disgusted Of Tunbridge Wells Silver badge
          Pint

          So it won't be Guinness Extra Cold?

          Thank God for that.

  6. Mr. V. Meldrew
    Coat

    Sheldon Lee Cooper....

    .... I told you before an I'll tell you again.

    Stop looking at the sky with a dirty telescope lens and no spectacles on.

    The only thing you'll find up in the sky is our god in heaven...

    (and maybe a rugby ballish bit of stone)

    God bless 'ya all, Mary. (PS Prayer meeting tonight cancelled due to Jumble Sale being double booked)

  7. MJI Silver badge

    Six Nations starts soon

    A coincidence?

    Hmmm

  8. Bob Dunlop

    Earth tides not that insignificant

    "The rocky part doesn’t move that much."

    A foot (30 cm) or more vertical displacement is not insignificant, it can upset GPS calibrations and similar. It's only the fact that the period is so long (12 hours plus) and that everything moves together that we don't notice it.

    1. Brewster's Angle Grinder Silver badge
      Facepalm

      Re: Earth tides not that insignificant

      I was about to have the same rant about solid earth tides. One of the groups they're hugely important to is....astronomers (using earth-based observatories to do detailed measurements).

  9. Anonymous Coward
    Anonymous Coward

    Rugby ball shaped?

    I'm not sure if I'm being pedantic or misunderstanding the tidal forces... I'm assuming it's actually a very oblate spheroid making it look like a rugby ball from the side only?

    Or... to be a rugby ball shape (prolate spheroid?), does that imply that the planet's rotational axis is at 90 degrees, similar to Uranus?

    1. KarMann Silver badge
      Boffin

      Re: Rugby ball shaped?

      I think they're saying it's stretched out by tidal forces along one axis, pointing toward & away from the star, so yes, a prolate spheroid, but with a fairly conventional axis, presumable roughly perpendicular to the orbital plane. The oblate spheroids are explained by centrifugal/centripetal force, nothing tidal to that at all.

  10. agurney

    I originally saw this reported on CNN with the headline "This giant exoplanet is so 'deformed' it looks like a football" .. and skipped it because, well, don't they all?

    1. MyffyW Silver badge

      It's not deformed, it's beautiful in it's own unique way ....

    2. W.S.Gosset Silver badge

      "2 nations separated by a common language" :)

      1. John Brown (no body) Silver badge

        ""2 nations separated by a common language proper football and battlechess"

        FTFY :-)

  11. artificial bitterness
    Angel

    Birth of a planet

    If it's now getting further away from the star -- WHEN DID IT HATCH?

    1. MyffyW Silver badge

      Re: Birth of a planet

      There was a Robert Swindells book* about a large interstellar creature laying eggs close to stars. It didn't usually end well IIRC....

      [*Amazon suggests "World-Eater", though I recall it might have been differently titled in my youth]

      1. John McCallum

        Re: Birth of a planet

        Depends The American book market sometimes have the same book with a differant title.

        1. Eclectic Man Silver badge
          Alien

          Re: Birth of a planet

          !!! SPOILER ALERT !!!

          At the end of 'The Light Fantastic'* by Terry Pratchett, some 'planets' orbiting a star hatch into baby star turtles, each with their own tiny disc world and supporting elephants.

          *Start with 'The Colour of Magic', as 'The Light Fantastic' starts off directly from the end of that book.

      2. Paul Kinsler

        Re: Birth of a planet

        More about the hatching than laying, but "Born of the Sun", Jack Williamson, 1934

  12. W.S.Gosset Silver badge

    Reminds me...

    Hal Clement's classic 1954 book: A Mission of Gravity".

    Set on a large planet spinning so fast it flattens out to look like an old style spinning top (days take minutes), such that the surface gravity varies hugely with latitude, which itself has all sorts of interesting consequences (eg, the sky+horizon looking inverted, bowl-shaped).

    Recommended! A great hard-sf classic.

    1. Anonymous Coward
      Anonymous Coward

      Re: Reminds me...

      fwiw, there is some Hal Clement on Gutenberg:

      https://www.gutenberg.org/ebooks/author/46167

  13. Anonymous Coward
    Coat

    Everyone knows

    It Takes Leather Balls to Play Rugby.

    Gas balls just wouldn't survive the scrum.

    1. John Brown (no body) Silver badge
      Mushroom

      Re: Everyone knows

      "Gas balls just wouldn't survive the scrum."

      Surely the opposite is the true case. The scrum wouldn't survive the gas balls.

  14. Jonathan Richards 1

    Pluto has entered the chat

    One of the defining characteristics of a planet, according to the IAU, is that it must be massive enough to assume a spherical shape under its own gravity. I think that this object thus cannot be a planet. </smug>

    1. KittenHuffer Silver badge

      Re: Pluto has entered the chat

      Nice try but the point of this article is that it's not its 'own' gravity that is causing the bulge!

      And technically within its own gravitational frame of reference the planet does think that it is spherical, it's just that due to the proximity to the star that frame of reference is a bit skewed.

      This is similar to the fact that light always travels in a straight line. Any light that 'bends' (lensing/micro-lensing) is actually still travelling in a straight line, it's just that the space that it is travelling through is warped such that a straight line is actually a curve as far as the rest of the Universe is concerned.

      1. Jonathan Richards 1

        Re: Pluto has entered the chat

        Ho, well, within my personal frame of reference I think I am Napoleon, but it doesn't get me much traction with the authorities.

        I am confident that a sphere is the solution to x² + y² + z² = C where x, y and z are cartesian coordinates and C is a constant, and this holds even in deep space. The source of the non-sphericity here is tidal deformation of the matter of the quasi-planet, not the gravitational warping of space-time.

        1. John Brown (no body) Silver badge

          Re: Pluto has entered the chat

          I'm just sitting here agreeing with both of you in case my head implodes!

    2. Anonymous Coward
      Anonymous Coward

      Re: Pluto has entered the chat

      Still one of my favourite book titles (by the astronomer most involved with the reclassification of Pluto):

      https://en.wikipedia.org/wiki/How_I_Killed_Pluto_and_Why_It_Had_It_Coming

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