If a gravitational field is relatively weak, such as that of a planet or an ordinary star, the following formula tells us that the fractional amount of gravitational time dilation at a distance r from the center of an object of mass
Mobject: (1/c2) X (GMobject/r)
(Recall that G= 6.67x10-11 m3 / (kg X s2) and c=3 X 108 m/s.) For example, while 1 hour passes in deep space far from the object, the amount of time that passes at a distance r is 1 hour multiplied by the factor above. Note that the formula does not apply to strong gravitational fields, like those near black holes. Use the formula to calculate the amount of time that passes on Earth’s surface while 1 hour passes in deep space.