Here's why:
* Orbital Velocity: The speed of an object in orbit depends on both the mass of the central body and the distance between the two objects.
* Gravitational Force: The larger the mass of the central body, the stronger the gravitational force it exerts. This stronger force requires a higher velocity for the orbiting object to maintain its orbit.
* Distance: The farther away an object is from the central body, the weaker the gravitational force, and therefore, the slower the orbital velocity.
Example:
* The Moon orbits Earth at a much slower velocity than the Earth orbits the Sun, even though the Sun is significantly more massive than Earth. This is because the Moon is much closer to Earth than Earth is to the Sun.
Conclusion:
The speed of a celestial body in orbit is determined by the mass of the central body and the distance between them, not simply by the size of the central body.