As I understand the metric expansion of space, space itself is expanding uniformly, isotropically. Distant light, passing through our solar system expands, as does the distance between atoms on earth. Any matter that is gravitationally bound does not expand, presumably, because gravity compensates by holding everything together, but it must be stretched apart before being held back together by stronger local forces.
So I did the calculations based on the current Hubble constant, and I determined that space everywhere is expanding by about 7% every billion years. So if the space between the sun and earth has expanded 7%, then I would expect it the orbit increase, and the length of a year to be shortened. Problem is, it seems like this is not accounted for in models of earths orbit.
So my question is, does light not expand as it passes through the solar system? And if not, then, how can that be explained in an isotropic universe? My understanding is that it is space that is expanding not the matter within it. If that is true, then I would expect all distances to be affected even between gravitationally bound objects like the sun and earth.