# Speed astronauts measure moving at the speed of light

Lets suppose a spaceship travels with v = 0.9c relative to the Earth. The time inside the spaceship would pass slower than on Earth. Would the astronauts measure a different speed (that means, a different one that the observer on Earth does) in relation to the same reference frame (Earth)?

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 Speed of what? What are these astronauts measuring? – Chris White Jan 12 at 1:32

The time inside spaceship would pass slower than Earth and distance measured by astronauts would be less than distance measured by Earth scientists. As $speed=distance/time$, they would observe different speed of something other than light. Speed of light would be observed same by all.