How much dimmer is the sun appear from Neptune than from earth?

Answer 1

Neptune is a heck of a lot farther out than 5 times the Earth's distance. More like 30 times as far which means you'd only get 1/900th the light.

Answer 2

It’s an easy sum.

Work out how many times further from the sun is Neptune than Earth.

That is, Distance of Neptune divided by Distance of Earth.

Then square that value – because the light drops off at square of the distance.

e.g. if neptune is 10 times as far from the sun (it is more in fact), the sunlight will be 10 x 10 = 100 times less.

Answer 3

Brightness is inversely proportional to the square of the distance.

So if Neptune was 5 times as far from the sun as the Earth, the sun would be 1/25 as bright.

So all you need to find out is how far Neptune is from the sun (look on wikipedia and find it's distance in AU's).
Square that number, and you have how much fainter the sun would appear at Neptune.

Answer 4

Since Neptune is about 19.19 AU's from the Sun vs Earth being only 1 AU from the SUN. So we know that through inverse square law that the sun would be 368.2561 dimmer on Neptune vs Earth (19.61^2=368.2561)