• Question: What Makes The World Round?

    Asked by xlxkelsey2k10xlx to Anne, Carolyn, Joe, Mariana, Nick on 18 Mar 2010 in Categories: .
    • Photo: Nick Bradshaw

      Nick Bradshaw answered on 18 Mar 2010:

      Not really my field, but I will give it a go! Basically beacuse of gravtiy and beacuse it has been spinning for a very long time. Spheres spin better than any other shape (they are more aerodynamic – the same reason that we play tennis will balls rather than cubes).

      Originally Earth would have been a huge cloud of dust and gas (bits of an exploded star) orbiting the sun which slowly pulled itself together by gravity. This would have started off small but slowly got bigger as more and more dust was pulled in. More of the this would tend to end uo on whichever bit of the Earth was closest to the centre (as gravity here would be strongest), so over time any big “holes” would have been filled in and a huge sphere would have formed.

    • Photo: Joseph Devlin

      Joseph Devlin answered on 18 Mar 2010:

      In a nutshell: gravity. Think of all the mass that makes up our planet (or any planet) but in its previous state as primarily a combination of gases. All that material is attracted to itself collapsing it into a more dense object. If the object were non-spheroid, then the parts that were further away would get pulled in until the whole thing was basically a sphere. This is the optimal shape to reduce the differences in forces. As the planet cooled and became solid (or at least more solid than gas), this sort of crystalizes.

      Of course, Earth isn’t a perfect sphere because of mountains and oceans but also because of our rotation, but that’s another issue. To a first approximation, it’s a sphere and gravity is the cause.

    • Photo: Carolyn McGettigan

      Carolyn McGettigan answered on 18 Mar 2010:

      Wow, tricky question for a neuroscientist!

      Well, apparently the Earth isn’t exactly spherical, but more like a slightly squished sphere (an ‘ellipsoid’). There’s a whole scientific discipline devoted to this stuff (geodesy – learned that 5mins ago), but I reckon it’s something to do with gravity and the Earth’s magnetic field, and achieving the most stable state in the presence of these effects.

    • Photo: Anne Seawright

      Anne Seawright answered on 18 Mar 2010:

      Erm, it isn’t completely round?

    • Photo: Mariana Vargas

      Mariana Vargas answered on 18 Mar 2010:

      Hello there… the Earth is round because of gravity that pull together material when the solar system formed (although it’s not perfectly round! it has an oblate shape because of the rotation).

      Or do you mean what makes the world go round? I understand that nothing in particular makes the world go round! what happens is that there is nothing to stop it… and after the formation of the solar system it just had momentum that has kept it going since!

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