How far can light travel?

Out there

You can see the Sun and stars, therefore light can travel over enormous distances (150 million kilometres from the Sun). There is no known limit to how far light can travel. But even very bright stars seem to be dim if they are a long way off.

Here on Earth

You cannot see torch beams or car headlights from a long way off.

Compared to a star, they are not very bright. What light there is spreads out from a bulb, so the further away your eye the smaller the share that you get. Also, some of the light from the bulb is scattered and absorbed by particles in the air, so there is less for your eye to detect.


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