Science of the observation of the sky; study of the stars. There is a freeware allowing to trek in the space with picture of met objects issued from NASA space programs. This is Celestia, whom the link is precised with the definition of 'Orbit'. Numerous planetariums, freeware, exist also and allow to have sky maps particularly complete. One of them is Stellarium, for example. The picture shows the Pleiads. See Orbit, Astrophysics and Cosmology.