As a planet draws away from the sun in its orbit, the force between the sun and the planet decreases and the planet’s speed also decreases.
This is due to the gravitational force between the sun and the planet, which follows Newton's law of universal gravitation. As the distance between the sun and the planet increases, the gravitational force decreases. According to Kepler's laws of planetary motion, as the planet moves farther from the sun, its orbital speed decreases.