Gravitation and Centrifugal forces combine together to keep planets in their respective orbits.

Gravitation:
- Gravitation is the force of attraction between two objects due to their masses.
- In the case of planets, the force of gravitation is exerted by the Sun, as it has a much larger mass compared to the planets.
- The gravitational force between the Sun and a planet acts as a centripetal force, pulling the planet towards the Sun.

Centrifugal Force:
- Centrifugal force is a fictitious force that appears to act on an object moving in a curved path.
- It is experienced by an object in a rotating frame of reference and acts outward from the center of rotation.
- In the case of planets in their orbits, the centrifugal force is caused by the planet's inertia, which tends to keep it moving in a straight line.
- This force acts outward, away from the center of the orbit.

Combining Gravitation and Centrifugal Force:
- In the case of planets in their orbits around the Sun, the gravitational force towards the Sun and the centrifugal force away from the center of the orbit are balanced.
- The gravitational force acts as the centripetal force required to keep the planet in its orbit.
- The centrifugal force, on the other hand, counteracts the gravitational force, preventing the planet from falling into the Sun.
- The balance between the gravitational and centrifugal forces allows the planets to maintain a stable orbit around the Sun.

Importance of the Balance:
- If the gravitational force were stronger, the planet would be pulled closer to the Sun, causing it to spiral inward and eventually collide with the Sun.
- If the centrifugal force were stronger, the planet would move away from the Sun, causing it to escape its orbit and move into space.
- The delicate balance between these two forces allows the planets to maintain their orbits, ensuring the stability of the solar system.

Conclusion:
The combination of gravitation and centrifugal forces is crucial in keeping planets in their respective orbits. The gravitational force acts as the centripetal force required for the orbit, while the centrifugal force counteracts the gravitational force, preventing the planet from falling into the Sun. This delicate balance ensures the stability of the solar system.