Measuring gravity on other planets using a pendulum involves understanding the relationship between the pendulum's period and gravitational acceleration. The formula T = 2π√(L/g) indicates that the period T of a pendulum is dependent on its length L and the gravitational acceleration g. By measuring the period of a pendulum on a different planet, one can rearrange the formula to solve for g, thus determining the planet's gravitational strength. This method relies on precise timing and knowledge of the pendulum's length. Overall, using a pendulum provides a practical approach to measuring gravitational differences across celestial bodies.