By analyzing the data available from passive scans. You are assuming that no strides have been made in scan sensitivity and spectral ranges over a thousand years or so, which is ludicrous. The data, in the form of signals from various types of materials and biological processes, is always present in the system, just waiting to be detected, just as are starlight and radio and x-rays here on Earth. Nothing instantaneous about it. The farside issue is a stretch, but I never assume that the FSS examines the entire planet, it just reports what it can detect. Perhaps there is some extrapolation based on statistical analysis. In any case, I assume a full-globe DSS mapping session is necessary to pin it down to specifics, including locations.Tell me again how we can instantaneously determine the composition of, calculate the distribution of elements in rocks on the surface of, and detect the presence of geological and biological activity on the far side of a planet 500,000 Ls away without 'breaking physics to pieces'?