How much dimmer does the Sun appear from Pluto than from the Earth?

1 Answer
Aug 7, 2016

On average, the ratio of apparent brightnesses is about 1560 to 1.


The apparent brightness of the Sun from any orbiting object varies, because the orbits are elliptical and so the distances vary. But on average Pluto is about #39.5# times as far from the Sun as Earth is.

Then the apparent brightness of the Sun varies inversely with the square of distance, so:

#{"Brightness on Earth"}/{"Brightness on Pluto"}=39.5^2=1560#.