On what scale does local gravity typically become the primary driver dictating motion, sometimes causing blueshifts despite cosmic expansion?

Answer

Within gravitationally bound groups and clusters like the Local Group

On smaller scales, such as within our Local Group, the gravitational pull between major bodies can overcome the general expansion of space, leading to local dynamics dominating.

On what scale does local gravity typically become the primary driver dictating motion, sometimes causing blueshifts despite cosmic expansion?
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