1. Method for estimating the movement of an observation instrument ( 10 ) on-board a vehicle flying over a celestial body, the observation instrument ( 10 ) comprising at least two strips (b 1 , b 2 ) with different lines of sight, each strip realizing the acquisition of successive image lines making up a composite image, by scanning its line of sight over the celestial body, parts of the composite images representing substantially a same scene of the celestial body, characterized in that the estimated movement is determined by optimization of an image similarity function that associates, to a given movement hypothesis, a similarity between values of matched pixels of at least a pair of composite images, matched pixels being pixels that represent, theoretically, the same point of the observed scene, given the considered movement hypothesis, and in that the method comprises, for each movement hypothesis considered during the optimization of the image similarity function, the following steps: ( 200 ) determining, for the at least one pair of composite images, at least one spatio-temporal transformation using the considered movement hypothesis and a geometric model of the observation instrument ( 10 ); ( 201 ) matching the pixels of the at least one pair of composite images using the at least one spatio-temporal transformation.