Why can you see faint stars better if you don't look directly at them? © Getty Images

Why can you see faint stars better if you don’t look directly at them?

Rod cells in your eye work better than cone cells in the dark, making them perfect for star gazing.

Asked by: Leah Victoria Smith, Hereford

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Astronomers call the technique ‘averted vision’, and it exploits the fact that our eyes contain two types of light-detecting cells. Around the centre of the retina are so-called cone cells, which give us colour vision and need good light levels.

Away from the centre are rod cells, which are responsible for black-and-white vision, and work better than the cone cells at low light levels. Looking off to one side allows more light from faint objects to strike the rod cells, and become visible to us.


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