Space may be expanding, though that doesn't mean that matter is (although Paul Dirac's LNH suggests otherwise): imagine a background of 'space' expanding but that not having any affect of the mass of the earth. @haydentaylor its not like an explosion because an explosion starts in a certain location and explodes through a pre-existing volume of space. Expansion has no centre (everywhere in the universe is the centre if you look at it that way, as all space in the universe derived from this small starting point).