• Question: Are there any particles in space if so how many different types are there?

    Asked by Befney to Julian, Jane, Hugh, Helen, Heather on 16 Nov 2014. This question was also asked by kaitlyno.
    • Photo: Julian Onions

      Julian Onions answered on 16 Nov 2014:

      Yes there are particles out in space, just many many less than on Earth.
      There are trillions of trillions of atoms per cubic centimetre on Earth in the atmosphere – whereas in outer space it may get as low as just one or two atoms per cubic centimetre.
      These atoms are mostly hydrogen and helium.
      However also present are particles of light, photons, which is light coming from stars. Also present are neutrinos, these travel very fast and are hard to detect.
      There are also we think dark matter particles in space too – but these are almost impossible to detect.

    • Photo: Helen Johnson

      Helen Johnson answered on 16 Nov 2014:

      Hi Befney, as Julian explained the particles in space are all very spread out – there’s less than 1 atom in every cubic metre of gas (imagine a box with all sides a metre long). Even galaxies are mostly empty space, because there are large gaps between each star. The distance between galaxies is even more incredible – the distance to our nearest galaxy is about 2 million light years. Imagine a huge cathedral or stadium – if you put a grain of sand in it that’s how ‘full’ space is.

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