In modified theories of gravity including a critical acceleration scale a0
, a critical length scale rM = (GM/a0)1/2
will naturally arise with the transition from the Newtonian to the dark matter mimicking regime occurring for systems larger than rM
. This adds a second critical scale to gravity, in addition to the one introduced by the criterion v < c
of the Schwarzschild radius, rS = 2GM/c2
. The distinct dependencies of the two above length scales give rise to non-trivial phenomenology in the (mass, length) plane for astrophysical structures, which we explore here. Surprisingly, extrapolation to atomic scales suggests gravity should be at the dark matter mimicking regime there.