We are marching through Luke’s use of “heaven” this week, and I’m not so sure we will finish. So here are a few more references:
Luke 12:56 You hypocrites! You know how to interpret the appearance of earth and sky, but why do you not know how to interpret the present time?
Luke 13:19 and the birds of the air made nests in its branches.
Luke 15:7 Just so, I tell you, there will be more joy in heaven over one sinner who repents than over ninety-nine righteous persons who need no repentance. … 18 I will get up and go to my father, and I will say to him, ?Father, I have sinned against heaven and before you … 21 Then the son said to him, ?Father, I have sinned against heaven and before you; I am no longer worthy to be called your son.?

Luke 16:16 The law and the prophets were in effect until John came; since then the good news of the kingdom of God is proclaimed, and everyone tries to enter it by force. 17 But it is easier for heaven and earth to pass away, than for one stroke of a letter in the law to be dropped.
Heaven is sky; it is up; it is the air above us.
Heaven is the presence of God so much that God’s presence can be called heaven.
Sin is against Heaven and God — that is, against God and his glorious presence.
Luke 16:16-17, like Mark 13:31, indicates that heaven and earth, as we know them now, might not be eternal. The Law, as the Word of God, is more permanent than heaven and earth. It could be a trope, on the other hand, for what is taken by everyone as permanent not being as permanent as God’s Word. It is also possible for the following schematic to represent Luke 16:16-17:
Law and Prophets –> John/Kingdom
Heaven and Earth –> Kingdom
That is, does “heaven and earth” stand here for the time of the Law and prophets passing away into the time of the kingdom. But, this means we have to deal delicately with the strokes of the law being more permanent than heaven and earth. Anyway, something to think about.