For some exoplanets within 50 light-years (15 pc) of the Earth by a method of the Geo-space universal X – structu re it is studied questions of the definition of the exoplanets parameters: density – diameter etc. I give also the Universal Geo – space X – structure theoretical Levels of the similarity of natural satellites of Solar system planets. From the theory in particularly follows the mystery similarity between the Mercury and the Earth’s Moon
Keywords: Geo-Space, Universal, X-Structure