Where g is the gravitational constant, with the value of 6.67×10-11n m2/kg2, r is the radius of the planet, and t is the period of the probe around the planet.
Therefore, as long as we can measure the radius or diameter of the planet and the period of the probe around the planet, it is easy to get the mass of the planet.
Measure the radius of the planet:
With regard to the measurement of the radius of the planet, we can measure the distance L from a point on the earth to the top and bottom of the planet with a rangefinder, and it is easy to know the angle θ changed by the instrument during the measurement. Then the radius r of the unknown planet can be easily calculated by using the mathematical knowledge of trigonometric function.
Extended data
When we have approximately calculated the radius of the planet, we can bring the measured value into the expression of the mass of the planet, thus calculating the mass of the planet.
From the above analysis, it is not difficult to see that the measured planet radius, the irregular shape of the planet and other factors, the final planet mass is only an approximation.
reference data
Baidu Encyclopedia-Law of Gravity