• Question: how big is our galaxy? do we even know the answer?

    Asked by Emma to Ashley, Bernard, Carsten, MariaMagdalena, Monique on 18 Nov 2015.
    • Photo: Monique Henson

      Monique Henson answered on 18 Nov 2015:

      It depends a little bit on where you say the galaxy ends. In the same way there isn’t a specific line dividing the Earth’s atmosphere and space, there isn’t a hard cut off between the edge of the galaxy and outer space. To give a rough estimate, it’s around 100,000 lightyears in diameter, which is around 950 000 000 000 000 000 kilometres – it’s pretty huge. Galaxies vary in size massively though – there are dwarf galaxies that are a lot smaller than ours (and usually dimmer). You can see some a photo of one here. There are also galaxies that are much bigger – these are usually elliptical galaxies that look like this

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