Christ Ascending on High
The Penny Catechism sums up all we need to know for practical purposes:-
Q. Where is Jesus Christ?
A. As God, Jesus Christ is everywhere. As God made man,
he is in heaven, and in the Blessed Sacrament of the Altar.
Yet it is natural for us to ask, ‘where is heaven?’ Or perhaps, more precisely, ‘where is heaven in relation to earth?’
Some people would say that this is a misguided question. They think of heaven and earth as spatially unrelated. According to this view, asking how far it is from heaven to earth would be like asking how far it is from Iceland to 1964. If they are orthodox, and accept that Christ still has a material body, they would in effect be saying that there are (at least) two different universes.
There are two problems with this. First, a philosophical one. Is it conceivable that any material body can travel from place A to place B, except by passing along a continuum uniting A and B? It seems not. St Thomas, at any rate thought not: Summa Theologiae 1a, q. 53, ad 2: ‘to move from one place to another without passing through the middle can pertain to an angel but not to a body’.
Secondly, a theological problem. Again according to St Thomas, there is only one universe (‘mundus’ – which means universe, not ‘world’ in the sense of an inhabited orb). He argues this both on the basis of Jn 1:10, mundus [not mundi] per ipsum factus est; and on the general principle that ‘whatever things are from God, have an ordering to Him and amongst themselves’. Considering His absolute power, that is, His power as mentally distinguished by us from His wisdom, God could have created any number of universes existing simultaneously, each ordered to Him, but not ordered among themselves. But this would have been to introduce an imperfection into creation.
So it seems to me that there is a distance, in principle expressible as a number of miles, between heaven and earth; though God has ordained that no mortal being will ever cross it.