https://wiki.kerbalspaceprogram.com/wiki/Science

The most efficient way to gather all science on a planet or moon from orbit is to enter a polar orbit at or near 90 degrees inclination, set the periapsis to the lowest point that will not impact the surface or the atmosphere and adjust the semi-major axis to twice the sum of the radius of the orbited body and the margin between high and low orbit. This will cause the craft to be at various times both high and low over every biome on the body, eventually gathering all science that can be gathered from orbit. For example, with the Mun this means a polar orbit of 90 degrees, with a periapsis of 20 Km and an apoapsis of 620 Km. Both the periapsis and apoapsis should be exactly at the equator for best results.