• Question: My question is how was our earth created and how can we be sure.

    Asked by Flammable Cow to Arthur, Clare, Daniel, David, Tora on 11 Nov 2014.
    • Photo: Tora Smulders-Srinivasan

      Tora Smulders-Srinivasan answered on 11 Nov 2014:

      Again, this isn’t my area of science, but the current theories (as far as I know) are that the earth was created from leftover bits after the sun was formed. And actually that all the planets in the solar system were created similarly.

      It’s possible that collecting information on Mars and combining it with what we know about the make-up of the Earth might tell us if they both had a similar origin in leftover bits of the sun.

      Does this agree with what you know about?

    • Photo: Daniel Parsons

      Daniel Parsons answered on 11 Nov 2014:

      Maybe David will give a better response as this is closer to his area of Science. However, from dating rocks we know that the Earth formed about 4600 million years ago. There was a big cloud of gas an dust in space that maybe got disturbed from a nearby exploding star. This caused waves in the giant disc-shaped cloud of material – and bits started coming together and as it did so the disk started to spin (a bit like an ice dancer who spins on the spot…as they pull their arms in they spin quicker!) – all these collisions caused clumps to come together that then bumped into each other to make small early planets called planetesimals. These objects collided over and over again and gradually got bigger, building up the planets in the Solar System, including the Earth.

      These exact details of how the Earth (and all the other planets) formed are still being worked out. The key bit of evidence is the types of materials that make up all the different planets, that gives us our main clues to test this model of how the solar system was formed. Scientists also study meteorites to see what happened in these earliest times in the Solar System.

      Have you been following the rosetta landing: http://rosetta.esa.int/ – the results from should tell us about the early solar system!!!

    • Photo: Clare Harding

      Clare Harding answered on 12 Nov 2014:

      Being sure is very hard in science! There is always a chance that someone will find a new fact and we will all change our minds (this bit usually takes a while!). However, we have lots of different pieces of evidence for the formation of the earth as Tora describes. Lots of geologists over many years have looked at the rocks in different layers and dated them (found out how old they were), the amount of isotopes (particular forms of elements) and how they must have been formed. This can tell us, for instance, that the earth was once covered in a layer of magma which was so hot it allowed all of the iron to sink into the planets core, which gives us the magnetic field.

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