It is not for you to know the times or seasons that the Father has established by his own authority. But you will receive power when the Holy Spirit comes upon you, and you will be my witnesses in Jerusalem, throughout Judea and Samaria, and to the ends of the earth.” When he had said this, as they were looking on, he was lifted up, and a cloud took him from their sight. While they were looking intently at the sky as he was going, suddenly two men dressed in white garments stood beside them. They said, “Men of Galilee, why are you standing there looking at the sky? This Jesus who has been taken up from you into heaven will return in the same way as you have seen him going into heaven" (Acts 1:7-11)
Ascension, by American artist John Singleton Copley, 1775
It is easy to overlook the words of the angels to Christ's disciples, but following Christ does not mean standing there looking up into heaven. I like to say that the angels level the gaze of Jesus' companions. Just why this is so is not revealed to them until Pentecost, when the Holy Spirit descends upon them and they begin to bear witness to the One whose kingdom they set about to proclaim and, at least to an extent, to establish.