Here's why:

* Distance: Pluto is incredibly far from the Sun, about 3.7 billion miles (5.9 billion kilometers) on average. That's about 40 times farther than Earth is from the Sun.

* Inverse Square Law: The intensity of light decreases with the square of the distance from the source. So, being 40 times farther away means the Sun's light is about 1600 times weaker on Pluto.

* Visual Brightness: The Sun would appear as a very bright star from Pluto, but not nearly as bright as it does from Earth. It would be similar to a very bright star seen from Earth, but with a distinctly yellowish hue.

Imagine looking at a flashlight from across a football field – the light is still there, but significantly dimmer than if you were holding it close. That's kind of like the Sun from Pluto.