"Comoving distance" factors out the expansion of the universe, which gives a distance that does not change in time due to the expansion of space (though this may change due to other, local factors, such as the motion of a galaxy within a cluster); the comoving distance is the proper distance at the present time.Two comoving objects at constant redshift formula_1 that are separated by an angle formula_30 on the sky are said to have the distance formula_31, where the transverse comoving distance formula_32 is defined appropriately.