What is the source of centripetal force that a planet requires to revolve around the sun ? On what factors does that force depend?

Explanation

### Step-by-Step Solution:

1. **Understanding the Concept of Centripetal Force**:
- When a planet revolves around the sun, it moves in a circular path. To maintain this circular motion, a force is required that acts towards the center of the circle. This force is known as centripetal force.

2. **Identifying the Source of Centripetal Force**:
- The centripetal force that keeps a planet in orbit around the sun is provided by the gravitational force between the planet and the sun. According to Newton's law of universal gravitation, every mass attracts every other mass.

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