• Question: How many Earths could you fit into Jupiter?

    Asked by anon-244744 to Ondrej, Jordan, Eleanor, Ed, Christine, Alice on 16 Mar 2020.
    • Photo: Edward Banks

      Edward Banks answered on 16 Mar 2020: last edited 16 Mar 2020 9:07 pm

      In terms of pure maths, Jupiter has a volume about 1300 times larger than that of the Earth (1322)! But you start to run into problems; you can’t squish spheres all that close to each other, there’s always some empty space in-between. If we assume that the Earth is perfectly spherical (it’s actually more of an oblate spheroid), and further assume optimal sphere packing- which is around 74%, that brings us down to only 978 Earths inside Jupiter.
      But I don’t think we really can assume optimal sphere packing, because we’re not putting them inside a box, we’re putting them inside another sphere! So using the previous 74% estimation, we’d probably cut some of the edges off. So let’s use the somewhat optimistic estimate of random sphere packing, which gives us about 65% packing- this brings us down to 860 Earths.

      Of course, once you get that many Earths close to each other then they will start to pull each other to pieces gravitationally, and you’ll end up with more compressed shapes, so maybe you could actually fit a lot more in… let’s not go in to those calculations right now!

    • Photo: Eleanor Jones

      Eleanor Jones answered on 18 Mar 2020:

      I love Ed’s answer. It really shows how many “issues” you could run into when considering what you would think of as a simple problem. Often thinking about one small question can lead to a myriad of more complications that you never even considered – which is what’s so fun about science!

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