# Is speed of light ( Sun-to-Earth ) related to the movement speed of solar system?

The speed of light has been measured to be 299 792 458 m/s. Now, the Solar System is traveling at an average speed of 828,000 km/h (230 000 m/s). Summing up the numbers we get close to 300 000 000 m/s

Does it mean, that the speed of light can be actually a relative number based on the movement of the source?

Does it mean that it IS actually 300 000 000 m/s but is calculated incorrectly due to sun moving round the galaxy?

• The Michelson-Morley experiment tested this. – Brandon Enright Mar 31 '14 at 15:44
• Also, 300,000,000 only looks special in our arbitrary base-10 system with arbitrary human-sized units. There is no reason to believe the speed of light should be any nice (to us) number. – Brandon Enright Mar 31 '14 at 15:47

## 2 Answers

No the speed of light in vaccuum is an absolute constant $c$ = 299 792 458 m/s

The way to add up relativistic speeds is:

$u' = \frac{u-v}{1-\frac{uv}{c^2}}$ to account for the constancy of the speed of light

You cannot simply add them up.

Edit: This also applies to normal everyday speeds. The reason we don't use this formula is because the speeds we are dealing with are too small and it simply doesn't matter. The difference is very very small to be noticable.

No. Speed of light in Vacuum isn't dependent on Solar System's motion. It's a constant. It'd be same even if the motion wasn't there.

Due to your question type problems, we've even calibrated our scales to create Relativistic Physics.