back to article Jupiter suffered growing pains before becoming our system's big daddy

Jupiter may be heavier than all the other planets in the Solar System combined, but it took a surprisingly long time to balloon in size. The gas giant is the fifth planet from the Sun and is the oldest planet, known for its magnitude and number of moons. It’s swollen and puffy with hydrogen gas, and measures about 318 times …

  1. james 68


    318 times the mass of the sun? Really?

    I think you might want to correct that, considering that in the reality where the planets orbit the sun and not the sun and planets orbit Jupiter it's around 0.001 times the mass of the sun, but it is 318 times the mass of earth.

    1. diodesign (Written by Reg staff) Silver badge

      Re: Doh!

      Software has bugs, and articles have brainfarts. It's fixed. Don't forget to email corrections at theregister dot com if you spot any errors.


      1. Richard 12 Silver badge

        Re: Doh!

        Can that email link be made a comment forum?


        Not everybody wants to send an email - or even can, depending on their browsing device.

        Sent from a kiosk

        1. Anonymous Coward
          Anonymous Coward

          Re: Doh!

          Can you imagine how many corrections like "You hate Apple", "You hate Microsoft", "I disagree with the author", "the authors mother was a hamster and their father smelt of elderberries" they would get?

      2. Claptrap314 Silver badge

        Re: Doh!

        Seriously, the email is a pain. For me, at least, the whoopsies happen often enough that I am in a near-constant state of being annoyed at being asked to play editor.

        For instance, the whopper about Jupiter being close to ignition mass. I'm not even a little bit an astronomer. But I know better than to accept that claim. I did follow the link to see if there was some sort of incredible discovery. No, that was an article about solid mass planets.

  2. Terje

    It would need to gobble up a fair bit more then just a little more mass to turn into a star, as the cutoff limit for a brown dwarf (still not rely a star) is about 13 Jupiter masses, it is true though that without changing other parameters (Such as a lot of heating by being excruciatingly close to the sun for example.) if Jupiter were to gobble up more gas it would stay approximately the same size.

  3. Anonymous Coward
    Anonymous Coward


    From article:

    "In the second phase, the planetesimals also added a bit of mass, but what is more important, they brought energy." The energy heated the young Jupiter’s atmosphere and prevented it from cooling down, where it could contract and accrete more mass.

    How can this be so? The inverse problem tells us that the gravitational pull would be the same is the atmosphere had contracted or not, as long as the mass was there. In fact, with an extended atmosphere it would catch more particles and today it is effectively a huge vacuum cleaner with a mighty suction and a giant dust bag, keeping our part of the solar system relatively free from hazards.

    1. Brewster's Angle Grinder Silver badge

      Re: Why?

      Mass comes in several classes: metre- to kilometre-sized planetesimals; mm and cm sized dust and pebbles; and gas. The primitive solar nebula is overflowing with gas, has about 1% dust, and has a sprinkling of planetesimals.

      When the primitive cores are barely more than wee planetesimals themselves, they accrete pebbles. Eventually they get big enough to sweep their orbit clear and keep it clear, and it this point they can't accrete any more pebbles ("the pebble isolation mass") and stop growing - except for increasingly infrequent collisions with planetesimals, comets and asteroids. That's what happened to the outer "ice" giants.

      But Saturn and Jupiter were able to successfully accrete gas and balloon up in size. It's this phase I suspect they're talking about. And I suspect it's routine hydrostatic equilibrium: the outwards pressure of hot gas, retards gas from being accreted. Eventually, after a few megayears, the gas envelope has cooled sufficiently and the planet increased in size to a point where it's gravitational attraction can overcome the thermal pressure and it wraps itself in gas like a stick wrapping itself in candyfloss.

  4. Kleykenb

    Not even close to a star

    It's a misconception that Jupiter got close to being a star. Even to become a brown dwarf it would need about 13x it's current mass.

  5. Doctor Syntax Silver badge

    "It’s also so big that if it gained any more mass it could actually shrink; all the gas would violently compress into a small ball and it would turn into a star."

    So stop sending up spacecraft to crash into it.

  6. Aladdin Sane

    violently compress into a small ball and it would turn into a star

    That actually happened 8 years ago.

    1. BoldMan

      Re: violently compress into a small ball and it would turn into a star

      I thought it happened at ten past eight?

      1. Aladdin Sane

        Re: violently compress into a small ball and it would turn into a star

        Then as well.

  7. 89724102172714182892114I7551670349743096734346773478647892349863592355648544996312855148587659264921

    Uranus doesn't want growing pains.

  8. Peter Clarke 1

    Compulsory Sci-Fi Reference

    Surely all it needs to become a star is a bazillion black Monoliths???

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