In theory, the loss of energy through gravitational radiation could eventually drop the Earth into the Sun. However, the total energy of the Earth orbiting the Sun (kinetic energy + gravitational potential energy) is about 1.14 × 10 joules of which only 200 watts (joules per second) is lost through gravitational radiation, leading to a decay in the orbit by about 1 × 10 meters per day or roughly the diameter of a proton. At this rate, it would take the Earth approximately 3 × 10 times more than the current age of the universe to spiral onto the Sun. This estimate overlooks the decrease in r over time, but the radius varies only slowly for most of the time and plunges at later stages, as r ( t ) = r 0 ( 1 − − t t coalesce ) 1 / 4 , with r 0 the initial radius and t coalesce the total time needed to fully coalesce.