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At night you only see faint stars if you look away.

Your retina carries about 120 million rods for dim light and some 6 million cones for colour and detail. In the fovea, your point of sharpest vision, there are essentially only cones – rods are absent there. That's why astronomers use averted vision and deliberately look slightly to the side.

Useful: A faint point of light vanishes the moment you fixate it, and returns off-centre.

Source: en.wikipedia.org

AugeSinne

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Question on this card

Why are faint stars easier to see when you look slightly off to the side?

  1. The pupil opens wider
  2. The fovea has essentially no light-sensitive rods
  3. The eye trembles less that way
  4. Cones are more light-sensitive than rods
Show the answer

Correct: The fovea has essentially no light-sensitive rods

The fovea contains essentially only cones; the dim-light rods sit further out.

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