Eli5: Why don’t we go blind staring at distant stars in the night sky, unlike staring at our own sun?


I’m guessing it’s the apparent magnitude? Can you explain like I’m five absolute magnitude vs apparent magnitude, flux and other related concepts in simple terms?

To add further, do we know how far from our own sun would you have to be so that it’s not blinding?

In: 1

This isn’t really a question about light, it is a question about geometry.

Stars emit a certain amount of light in every direction. You can model the amount of light as being spread out over the surface of a sphere with a radius of your distance from the star. The surface area of a sphere can be calculated by multiplying 4 times pi times the radius squared.

As the radius increases so does the surface area of the sphere. The same amount of light then is spread out over a larger area, meaning the light in a given area reduces.

The light from a star goes out in all directions, so in 3D space, it would decrease according to the inverse square law. That means the amount of light coming from a star decreases as you move away from it by the same factor squared. For example, Jupiter is about 5x as far from the sun as we are, therefore the sun would appear to be 25x dimmer on Jupiter.