Science and Education Publishing International Journal of Physics 2333-4886 3 1 2015 01 13 Gravitational Mass Defect 29 31 EN F. F. Mende B.I. Verkin Institute for Low Temperature Physics and Engineering NAS, Ukraine, Lenin Ave., Kharkov, Ukraine IJP2015315 10.12691/ijp-3-1-5 2014 11 17 2014 12 01 2015 01 13 Explosive energy in the nucleus of the galaxy NGC 3034 composed 9 ? 1048 J. In this case of its nucleus of galaxy was rejected the mass equal to 5,9 ? 107 of the masses of the sun. At present are not known the physical mechanisms, which can explain such immense explosions. In the article is examined the new physical phenomenon, gravitational mass defect, which can explain the phenomenon indicated. This phenomenon leads to the fact that the summary mass of bodies before and after the collisions differ. Indicated we will call mass defect gravitational mass defect and it can serve as a reason for explosions in the nuclei of galaxies.