back to article Your FREE end-of-the-world guide: What happens when a sun like ours runs out of fuel

When a star dies, destroying so much around it, it’s the small, dense rocky planets that are the objects most likely to be left standing while the heavy, gassy planets crumble and perish. A team of astrophysicists came to this conclusion after modeling the tidal interactions between a white dwarf star and a nearby planet to …

  1. Anonymous Coward
    Anonymous Coward

    Perhaps

    Theresa May will still be clinging-on as Prime Minister and still not have got Brexit over the line by then ?

    1. Rich 11 Silver badge

      Re: Perhaps

      She plans to delay the heat death of the universe by getting Parliament to debate her deal, time and time and time again.

      1. Dan 55 Silver badge

        Re: Perhaps

        In an ever-expanding universe the rest of Westminster could have accelerated away from her, clinging onto the dispatch box, in a starless void. And she still wouldn't manage to get an agreement.

        1. hopkinse

          Re: Perhaps

          Welcome to the Brexit at the End of the Universe. Watch Theresa May implode while dining on Ameglian Major Cow and sipping a particularly fine Pan Galactic Gargleblaster. With guest speaker

          Max Quordlepleen.

      2. Arthur the cat Silver badge

        Re: Perhaps

        She plans to delay the heat death of the universe by getting Parliament to debate her deal, time and time and time again.

        Surely all that hot air will accelerate the heat death?

        1. Rich 11 Silver badge

          Re: Perhaps

          Surely all that hot air will accelerate the heat death?

          Arguably any activity would accelerate heat death, but in this case I think we have to allow for interdimensional transfer of energy to members of Parliament from the Eighth Circle of Hell.

    2. TheVogon Silver badge

      Re: Perhaps

      "Theresa May will still be clinging-on as Prime Minister"

      Only because everyone knows that the alternative of Corbyn is much worse.

  2. Sgt_Oddball Silver badge
    Mushroom

    I am Jack's complete lack of surprise...

    So the sun's still going to get us in the end as pretty much a given.

    We'll have brought the sun much closer to ourselves by then anyways, via much more portable packages, though somewhat shorter lived (see icon).

    1. tfb Silver badge
      Mushroom

      Re: I am Jack's complete lack of surprise...

      Tangentially relevant to the nuke thing: although we know that the Sun is too small to be a candidate for a future supernova, if it wasn't there's an interesting question:

      which is brighter: a supernova seen from the distance we are from the Sun, or an exploding hydrogen bomb pressed against your eyeball?

      The supernova is brighter, by nine orders of magnitude. Inevitably this comes from what-if.xkcd.com. Supernovae are just fucking silly.

      1. I ain't Spartacus Gold badge
        Happy

        Re: I am Jack's complete lack of surprise...

        Erm, does this matter? How am I supposed to grade the level of brightness at these ludicrous levels? This on goes up to 11 man...

        Oh and what factor of suncream to I require for the experiment?

        1. Francis Boyle Silver badge

          I don't

          anything on What If matters. Doesn't stop it being interesting though.

      2. I ain't Spartacus Gold badge
        Mushroom

        Re: I am Jack's complete lack of surprise...

        tfb,

        Sadly only one upvote to give you. As I've just read the xkcd link you provided, and it's even more cool and interesting than that.

        Sure it's amazing how bright that supernova is.

        But he's using it as an illustration of how stupidly amazing supernovae are. In that you can get an instantly lethal does of neutrino radiation out to about the orbit of Mars.

        So assuming that you built a bunker in the centre of Mars, with really good air conditioning and survived the expansion of the star, the absurdly stupidly ludicrously huge numbers in the neutrino burst would simply wander through the planet, as neutrinos do, and kill you anyway. That's a lot of neutrinos. Given our detectors at the bottom of mines pick them up in ones, out of the zillions passing through the Earth all the time.

        1. magickmark
          Thumb Up

          Re: I am Jack's complete lack of surprise...

          "So assuming that you built a bunker in the centre of Mars, with really good air conditioning"

          Sounds like the perfect position to listen a Disaster Area concert, shall we book them now?

      3. Michael H.F. Wilkinson Silver badge

        Re: I am Jack's complete lack of surprise...

        Supernovae are really cool, but you wouldn't want one to go off in your back garden. There is actually one visible in 8" scopes in NGC 5353 at the moment, a comfortable 110 million light years away. It is the 14th one I have managed to see. Odd to think that when this last one went off dinosaurs were roaming the earth

    2. bombastic bob Silver badge
      Trollface

      Re: I am Jack's complete lack of surprise...

      don't worry, some wackos will claim it's human activity causing the sun to die, and come up with charts and graphs and modeling and legislation to curb our personal freedoms and screw us up economically in order to "solve" it.... and accuse EVERYONE who doesn't buy into this nonsense of being "deniers"...

      (troll icon, naturally)

  3. Blockchain commentard Silver badge

    The Sky at Night has always said our Sun will expand as it dies, engulfing us, before shrinking. Does that now mean I need to stockpile factor 1 million sun cream?

    1. disgustedoftunbridgewells Silver badge
      Mushroom

      Don't be stupid. Your sun cream will have gone off by then and you'll have to buy more.

    2. Chrissy

      Like a red-head at the beach.... wear a t-shirt

  4. rmason Silver badge

    We all know

    The Great Prophet Zarquon returns.

    At Milliways.

    This is fake news.

    1. Anonymous Coward
      Anonymous Coward

      Re: We all know

      I'll see you there and we'll meet the meat ..!

  5. Mystic Megabyte Silver badge
    Joke

    Seen this before

    “Our study, while sophisticated in several respects, only treats homogenous rocky planets that are consistent in their structure throughout. "

    They used snooker balls?

    1. Anonymous Custard Silver badge
      Trollface

      Re: Seen this before

      Nah, in a vacuum everyone knows you can only use spherical cows.

      1. Spherical Cow

        Re: Seen this before

        That's what I assumed ;-)

  6. David Harper 1

    It's worse than you think

    The Sun's luminosity and surface temperature are increasing by about 10% every billion years, so in a couple of billion years time, the Earth's surface will be too hot to sustain liquid water. Game over. And in five billion years, when the Sun runs out of hydrogen and turns into a red giant, there's an even chance that it will swallow the Earth as it expands. Mercury and Venus are definitely doomed to this fate, and the Earth may also end up inside the Sun.

    But on a truly astronomical timescale, on the order of 10**38 years, all baryonic matter will vanish as protons decay into muons and electrons. Then we're *really* stuffed. (Reference: "A Dying Universe", F.C. Adams and G. Laughlin, 1997, Reviews of Modern Physics, Vol. 69, pp 337-372)

    1. disgustedoftunbridgewells Silver badge
      Pint

      Re: It's worse than you think

      "so in a couple of billion years time, the Earth's surface will be too hot to sustain liquid water."

      But it'll be a dry heat

      1. Kane Silver badge
        Mushroom

        Re: It's worse than you think

        "But it'll be a dry heat"

        Time for a barbecue then!

    2. I ain't Spartacus Gold badge
      Happy

      Re: It's worse than you think

      Oh well. Just enough time for a nice hot bath then...

    3. Robert Helpmann?? Silver badge
      Childcatcher

      Re: It's worse than you think

      Mercury and Venus are definitely doomed to this fate, and the Earth may also end up inside the Sun.

      This would be true in a stable system, but there is a good chance that Mercury will eventually be out of its orbit and roaming elsewhere by that point.

      1. bombastic bob Silver badge
        Devil

        Re: It's worse than you think

        you sure about mercury leaving orbit? I would expect it to crash into the sun before that would happen... due to very slow orbital decay from solar wind, if for no other reason.

        so that's something to ponder I guess, if mercury's orbit is affected more by constant mass loss from the sun [energy from fusion as well as solar wind], or by the solar wind itself creating friction and orbital decay.

        As mass of the sun goes down, mercury's escape velocity would ALSO go down, but very very slowly. Similarly, the slow orbital decay. Maybe they balance each other out?

      2. David Harper 1

        Re: It's worse than you think

        "This would be true in a stable system, but there is a good chance that Mercury will eventually be out of its orbit and roaming elsewhere by that point."

        Reference to peer-reviewed paper in a reputable journal, please?

        1. David Harper 1

          Re: It's worse than you think

          Answers own question:

          Existence of collisional trajectories of Mercury, Mars and Venus with the Earth

          Laskar, J. & Gastineau, M. (2009)

          Nature, 459, pages 817–819 (11 June 2009)

          https://www.nature.com/articles/nature08096

          Jacques Laskar is the real thing when it comes to Solar System dynamics. This paper reports numerical simulations of the orbits of the planets over 5 billion years. In around 1% of them, the eccentricity of Mercury's orbit is pumped up by secular resonances, leading to scenarios where it plunges into the Sun or collides with Venus. In one scenario, the orbits of all four inner planets are de-stabilised, with catastrophic consequences.

          Don't have nightmares :-)

  7. Anonymous Coward
    Anonymous Coward

    homo sapiens has a solution for EVERY problem :)

    buy one shovel and get 2nd ABSOLUTELY FREE

  8. JimPoak

    The World Will End

    I think this a bit academic. The image it's self show's a solar system exploding outward.

    Red Giant sweeping along the inner planets and so cooking the rocky bits to a crisp but intact

    As fissionable material dwindles the sun will collapse sending out a shock wave (OK we're saved, whoops)

    The much loved book Isaac Asimov collapsing universe before I'd even heard of Stephen Hawking as my mantra

    The alternative version is:-

    The world will end a week next Tuesday.

    Note to Siti 3000 BCE before the written word who would have considered communication through radio waves?

    1. DJV Silver badge

      Re: The World Will End

      I see lots of words that are, individually, mostly correct and understandable but your post, taken as a whole, has completely done my head in. Have you been taking lessons from amanfrommars?

      1. VikiAi Silver badge
        Happy

        Re: The World Will End

        They have been taking something, that's for sure!

  9. Aristotles slow and dimwitted horse Silver badge

    So what that means...

    So what that means from an Existential philosophical perspective is that no-one gets out of here alive? No one. At any point. Anywhere. Which then makes the meaning of life (not that I actually believe there is one) to be to stop worrying and just enjoy the time while we are here, because as Proximo said to Maximus... "ultimately we're all dead men".

    Which in turn means that the philosophy of Bill S Preston Esq. and Theodore "Ted" Logan were right all along. Whoah!!!!

    1. Dan 55 Silver badge

      Re: So what that means...

      The meaning of life is to propagate itself, so you get bonus points if you help unlock the space-faring civilization or keep Earth habitable achievements. Being excelent to each other might help others achieve that goal even if you directly don't.

      1. Anonymous Custard Silver badge
        Trollface

        Re: So what that means...

        And don't do your homework without wearing headphones...

    2. Dave 32
      Coat

      Re: So what that means...

      The meaning of life? Well, obviously, the answer is 42.

  10. Aladdin Sane Silver badge

    Can't it happen any sooner?

    1. bombastic bob Silver badge
      Devil

      yeah let's dump nukular waste into the sun and make it go 'critical', that'll speed it up!

  11. Rudolph Hucker the Third
    Thumb Up

    "On a long enough timeline, the survival rate for everyone drops to zero."

    Just so El Reg isn't accused of plagiarism:

    (C) Copyright Chuck Palahniuk, Fight Club 1996

    FTFY

  12. G R Goslin

    Tidal forces?

    I fail to see where tidal forces come in. The sun will have substantially the same mass, through time, and gravity is a function of mass (and distance) neither of which stand to change. Strictly, gravitational force is the attraction between two (or more) bodies, or the constituents of one body. So, nothing changes substantially, in a gravitational sense, as the sun dies, to the orbiting bodies

    1. David Harper 1

      Re: Tidal forces?

      Not so. The orbiting bodies raise tides on the central body. Energy and angular momentum are exchanged. The orbits change. This is why the Moon is slowly drifting away from the Earth and the Earth's rate of rotation is decreasing. That in turn leads to the need for leap seconds, and hey presto, it becomes an IT problem :-)

      1. FrogsAndChips Bronze badge

        Re: Tidal forces?

        Still, the mass of the Sun is not going to increase, it should even decrease when the outer layers are expelled. From the point of view of a planet, the star's gravity has not increased, so why would tidal forces increase to the point that they can rip it apart?

        1. David Harper 1

          Re: Tidal forces?

          The force of gravity grows stronger, the closer you approach a massive object such a a star or gas giant like Jupiter. Now consider a planet or moon orbiting such a massive central body. There's a critical distance, known as the Roche Limit, where the difference between the force of gravity on the star/planet-facing side is so much greater than the force of gravity on the side furthest from the star/planet that it tears the orbiting body apart. This is a likely scenario for how Saturn's rings were formed: a small satellite's orbit took it so close to Saturn that the differential gravitational forces ripped it apart. It's also the fate that awaits Phobos and Deimos, the moons of Mars, which are slowly spiralling in towards the planet.

        2. TechnicalBen Silver badge

          Re: Tidal forces?

          The distribution of the gradient does change.

          See below. Consider a black hole of 3 sun masses, and a red giant of 3 sun masses. The Roche Limit, of each would be different (AFAIK, I've not googled the math to check it, sorry, I'm a layman! :P ).

          PS, it seems that "R" radius of the larger body (Sun in our case) is influential in the variable of the Roche Limit. :)

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

          I guess this is because each position in the volume of the star/planet will also have a gravitational gradient caused by the surrounding material (if it's the size of a planet, it's a lot of rock! and you can be gravitationally pulled in any direction the material is, just less on your side with less material ). Imagine falling through a planet or star, you would feel gravity pulling in both directions as you pass the center, but still get some gravity on both directions until you reach a surface where all the gravity would then be in one direction (as the whole star/planet would be on one side of you).

          So the gradient in gravity will effect how strong a "slope" and difference is exerted on the second/smaller body.

          1. KarMann

            Re: Tidal forces?

            You're misreading that Wikipedia article. Yes, R_M appears in one of their equations, but only because that's the one that compares their densities, rather than their masses directly. In the case we're considering here, the density and radius are changing, but the mass is staying relatively constant. Radius of the Sun doesn't enter into it. The only situation where it's relevant to the gravity field when comparing spherical bodies is when you'd be within one of them.

            ETA: See also Wikipedia on the shell theorem, https://en.wikipedia.org/wiki/Shell_theorem . It's pretty much what you were saying in your penultimate paragraph.

            1. TechnicalBen Silver badge

              Re: Tidal forces?

              I also missed that due to GR you don't feel gravity "pulling" in both directions... (as gravity/acceleration is all you feel and cannot distinguish between it).

              I'm still trying to understand how distributing the mass over a greater space does not change the shape of the gravitational field the earth would be in. We are talking about inflating the sun to the size of our current orbit here! (As you say, when R becomes large enough to overtake the earth).

              Though I will concede if I can figure out/be shown how the math/field/etc does not change shape/concentration as the size of the sun increases or decreases.

              1. FrogsAndChips Bronze badge

                Re: Tidal forces?

                Just have a look at the WP article on Shell theorem mentioned above by KarMann, the math is detailed there. It demonstrates how the gravity field outside an homogeneous spherical body is the same as if all the mass was concentrated at the center of the body. It derives that the gravity only depends on the mass of the body, not its size, however close you may be to its surface.

  13. TVU Silver badge

    "What happens when a sun like ours runs out of fuel"

    The response to that scenario is easy - you emigrate to a habitable planet around a K or M class star because they last tens of billions of years.

    1. HildyJ
      Alert

      "What happens when a sun like ours runs out of fuel"

      Finally, a use for all that coal nobody (besides Trump) wants anymore.

    2. TechnicalBen Silver badge

      Earth...

      The best space ship we have. What are the probabilities of losing our sun and moving in with a nice younger model? (wandering/lone planets exist... but I think are rather rares than stellar collisions during galaxy mergers).

      1. eldakka Silver badge
        Coat

        Re: Earth...

        What are the probabilities of ... moving in with a nice younger model?

        For people over 30, the chance of that is inversely proportional to money/age2. Where money is in millions of dollars. The full formula is:

        1 - money/(age2)

        e.g. have $1billion and are 40 years old:

        = 1 - (1b/1m)/(402)

        = 1 - 1000/1600

        = 1 - 0.625

        = .375

        if you have $1billion and are 90 years old:

        = 1 - (1b/1m)/(902)

        = 1 - 1000/8100

        = 1 - 0.123

        = 0.877

        1. FrogsAndChips Bronze badge
          Holmes

          Re: Earth...

          If you have $2 billion and are 40, the probability becomes negative. What do you make of it?

  14. SirDigalot
    Coat

    so am I the only one heading to the horse and groom for some liquid relaxant and protein replenishment then?

    >>>>>> it's a towel >>>>>>>

    1. magickmark
      Thumb Up

      Remember to feed the small dog the cheese sandwich on the way out !!

  15. Ribfeast

    Surely the drag caused on the orbiting planet from all the gases and plasma it is orbiting through would cause it to de-orbit into the dying star?

  16. Long John Brass Silver badge

    Easy fix for dear old Sol

    Star-Lifting (https://en.wikipedia.org/wiki/Star_lifting)

    Given that our Sun is 99.8% of *all* the mass in our solar system; If we can extract elements heavier than Hydrogen, we have all the building materials we need and we can then feed the hydrogen back into the sun extending it's life!

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