When a planet is in a uniform circular motion, it is always at the same distance from the sun.
The gravitational force between the sun and the planet provides the necessary energy to keep the planet in the orbit.
This gravitational force is responsible for the centripetal force on the planet.
But the tangential velocity changes its direction in each moment of time due to the centripetal acceleration.
The speed of the planet around the circular orbit remains the same. But the velocity component varies at each point because it is a vector that has a direction.
However, the angular velocity of the planet remains the same which is a vector.
