Solar system measurements and the local Hubble tension

The existing astrophysical paradigm asserts that cosmological expansion does not operate on gravitationally bound bodies. However, there is now considerable evidence that such expansion does occur within the Solar System. Seven quantitative estimates of “local” expansion phenomena suggest that H 0 , the mean (±σ) current value of the Hubble‐Lemaître parameter, is (49 ± 11) (km/s)/Mpc. That is far lower than has been derived from analysis of the cosmic background radiation, i.e., H 0 = (67.4 ± 0.5) (km/s)/Mpc or the luminosity of type Ia supernovae, i.e., (73.04 ± 1.04) (km/s)/Mpc. Furthermore, there are several other situations within the Solar System where precise values are less readily obtained, but there is some suggestion that H 0 might also have a lower value. These findings, when considered alongside the large-scale “Hubble tension,” may support the suggestion that H 0 may be scale-dependent, although the physical origin of that effect is unclear.