• Question: Why is there sea

    Asked by peaches247 to Donna, Jo, Mark, Stuart, Tim on 17 Jun 2010 in Categories: .
    • Photo: Mark Lancaster

      Mark Lancaster answered on 16 Jun 2010:


      That’s a good question – tricky – I don’t think there is an accepted answer to this one – one theory that I’m familiar with is water-rich meteorites/asteroids bombarded the earth bringing water with them.
      Hydrogen is the most abundant element in the universe and oxygen although far less abundant is very reactive so it’s not too surprising that icy asteroids formed and then that they bombarded the earth….

    • Photo: Joanna Buckley

      Joanna Buckley answered on 16 Jun 2010:


      Nice question, peaches247!

      I believe it’s because we’ve been hit very many times by meteorites packed full of water. They were just sort of left here by them.

      Water is a very simple molecule and hydrogen and oxygen are very reactive so it’s easy for them to combine.

      Do you know in a 100-year period, a water molecule spends 98 years in the sea, 20 months as ice, about 2 weeks in lakes and rivers, and less than a week in the atmosphere. Cool, huh?

    • Photo: Donna MacCallum

      Donna MacCallum answered on 16 Jun 2010:


      Oceans are amazing – they cover 70% of the Earth’s surface but contain 97% of all of the water on Earth!
      The oceans and seas are the source of water vapour into the atmosphere to produce rain for freshwater, which eventually makes its way back into the sea. Not only that but the oceans also affect weather and climate.

      The oceans also amazingly contain 50-80% of all life on Earth – absolutely amazing!

    • Photo: Tim Craggs

      Tim Craggs answered on 17 Jun 2010:


      What an interesting question. I suppose there is sea, because such a large proportion of our planet (at least on the surface) is made up of water. But that just leads us to another question, why is there so much water?

      Any ideas?

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