• Question: How did the world start

    Asked by ! ROW-SEY ! to Pierre, Joe, Jos, Kate, Lisa on 14 Nov 2014. This question was also asked by sam, 653tema26.
    • Photo: Pierre Lasorak

      Pierre Lasorak answered on 14 Nov 2014:

      Hi
      World as Earth? So basically we all come from stars, in fact planet Earth is a big amount dust from a dead star! We don’t come straight from the Big Bang because in the Big Bang, you basically have not enough time to create heavy elements like Carbon, Oxygen. There is only Helium and Hydrogen after the Big Bang… So you have to wait that these light elements come together through gravitation in a star. Then they react with a nuclear process -which we call fusion- to create heavier elements. Once this is finish, the star has not enough light elements to make fusion. If there is not enough gravitation pull any more, everything explode (that’s a supernova) and produce an enormous amount of dust of heavier elements. Once this dust come together again, you form the Earth and the planets!

    • Photo: Joe Reed

      Joe Reed answered on 17 Nov 2014:

      Initially our solar system was a big cloud of gas and dust that was spinning. At the centre it became very dense and very hot until eventually our Sun was born.
      Gas and dust continued to orbit the sun. Sometimes bigger lumps would form due to gravity and bump into other lumps and join to them. Over millions of years these lumps became planet sized. And one of them, the third from the sun, is us, the Earth.

    • Photo: Kate Dobson

      Kate Dobson answered on 17 Nov 2014:

      Carrying on from where Pierre and Joe finished…. in our case the dust clumps together to form asteroids, and then asteroids stick together to form planetesimals, and the planetesimals get bigger. As they get bigger the pressure in the middle of them increases (the weight of the rock above them gets more) Once the size of the planetesimals reaches about 1000 km it’s own mass starts to make it into a spherical shape we know as rocky planets.

      Eventually the pressure and temperature in the middle of the planetesimal becomes high enough to start melting the dust, and then once things are molten the light elements begin to float up, and the heavy element begin to sink. This led to the formation of the iron rich core and the iron poor crust. All this time the p0lanetessimal would be being hit by more asteroids and there would have been lots of volcanoes as the thin cool crust was broken by the impacts. Most researchers think that the tilt of the earth was caused by one major impact that formed the moon.

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