How does doubling the aperture diameter affect a telescope's light-gathering power?
Answer
It gathers four times as much light.
Light gathering power is directly related to the area of the main light-collecting element, known as the aperture. Since the area of a circle is proportional to the square of its diameter ($D^2$), if the diameter of the aperture is doubled (multiplied by 2), the light-gathering capacity increases by a factor of $2^2$, resulting in four times the light capture. This increased capacity is vital for making faint objects visible and for reducing the negative impact of background skyglow when observing from light-polluted environments.
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