Large distances are the realm of astronomers with the characteristic that one cannot experiment but only deal with the information we can collect from the Heavens, primarily of electromagnetic nature, even though new promising messengers such as the neutrino astronomy and the emerging one with gravitational waves, are just ahead of us with new challenges. In this brief overview, given the broadness of the field, I have attempted to show that an astronomer dealing with precision measurements must display the same rigour as a metrologist in his/her laboratory, by ceaselessly controlling his apparatus and above all calibrate and calibrate again. The metrological spirit pervades every area of experimental and observational science, whatever the scale of space or time under consideration.