We know (measured) that a clock on a mountain "ticks" faster than a clock at sea level. At higher altitude, the clock runs even faster. Now, if we go much higher, towards the Sun, on the line between the center of the Earth and the center of the Sun, the clock should begin, at some point, to run slower, influenced by Sun's gravitation. Where is that "point" (where the clock would stop increasing its tick rate and then start to decrease again), at what distance from the center of the Earth? It was calculated and/or tested experimentally? PS I asked the same question on another forum and made some progress in finding the answer, but it seems that the value I got is not good enough ... Please help.