2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/5301Following a quantum-gravity approach we use a gravitational quantum defined elsewhere as well as an effective gravitational "cross section" in conjunction with Mach's Principle and the de Broglie wavelength concept. We find the speed of gravity v_g related to a gravitational mass m as given by v_g of order c (M_u/m)^(1/2), where c is the speed of light and M_u the mass of the seeable Universe. For the solar system we get v_g of order 10^(11) c, which agrees very well with experimental results. For the Universe v_g is of the order of c.To be submitted to New Journal of Physics; 3 pages; LaTeX fileAstrophysicstext