Abstract. The analysis of solar radiation pressure force and its influence on the motion of artificial satellites has been developed by researchers. Accurate models to describe the influence of the Earth's shadow on the torque and force due to solar radiation pressure have been presented. In this work the solar radiation torque (SRT) and its influence on the attitude of an artificial satellite are taken into account by the introduction of the Earth's shadow function in the equations of motion. This function assumes a unitary value when the satellite is in the fully illuminated region of its orbit, and the value zero for the full shade region. The main objective of this study is to analyze the magnitude of SRT using the equations described by quaternions during a 35 day period and to compare the results with the satellite transition through the shadow region and the time interval in this region. The duration and transition through the shadow region were obtained using the software "Shadow Conditions of Earth Satellites". The formulation is applied to the Brazilian Data Collection Satellites SCD1 and SCD2, and the torque model is presented in terms of the satellite attitude quaternion, distance of the satellite to the Sun, orbital elements, right ascension and declination of the Sun. IntroductionThe study of the rotational motion of artificial satellites leads to a more precise results when the torques caused by external forces that influence their motion are included. In this paper, the force caused by the solar radiation pressure is one of the external forces that has been modeled, taking into account the effects of Earth´s shadow, and inserted in the equations in order to propagate the rotational motion of the artificial satellites.In the literature several papers considered the influence of the solar radiation torque (SRT) on the attitude of the artificial satellite [3,6,7,9,11,12]. Most of them modeled the torque acting on the artificial satellite and determine analytical and numerical solutions for the dynamic system of equations describing the rotational motion of the satellite, including the shadow region of the Earth.The goal of this paper is the analysis of the magnitude of the SRT during a 35 day period using the Brazilian Satellites SCD1 and SCD2 data. Here it is assumed that the orbital motion is known and given by the problem of two bodies and quaternions are used to represent the space orientation (attitude) of the satellite. The equations of motion are given by Euler's equation, relating the rate of change of the components of the satellite angular velocity with the external torques, and by the attitude