How fast is light?

Question

Setup: I am at point A and point B is an object between point A and the source of light (Point C) {could be the sun}.

How long would it take for the light from point C to reach point A once B is removed, if the distance between A and C is (x) light years/miles away?

What i'm really asking is, is the speed of light dependent on the distance between point A and point C?

Could you give me some examples such as:

If the distance between point A and C is ___ miles then it would take the light from point C _____ amount of time to reach point A.

Is there a formula for this?

Answer 1

The speed of light is a constant 186,000 miles per second!

Answer 2

When you say "once B is removed" you are suggesting that B is blocking the light between C and A. If so...

If B is blocking the light between A and C, then the time it takes A to see C's light when B is removed is the distance between A and B, divided by the speed of light. How far away C is does not affect anything.

Example, an eclipse with the moon (B) blocking the light from the sun (C), and the observers are on Earth (A). When the moon (B) moves, the time it takes for someone on Earth (A) to see the light from the sun (C) is (distance A to B)/c. In this specific case... say 380,000 km / 3x10^8 m/s = 1.267 seconds.

It would be the same if C was light from a distant star. As the moon moves out of the way, you see the star's light 1.267 seconds later.

The distance to C doesn't matter as B can't block the light unless the light from C had already reached B. Otherwise it wouldn't be blocking it.