Christ's Ascension marks the definitive entrance of Jesus' humanity into God's heavenly domain, whence he will come again (cf. Acts 1:11); this humanity in the meantime hides him from the eyes of men (cf. Col 3:3).
Jesus Christ, the head of the Church, precedes us into the Father's glorious kingdom so that we, the members of his Body, may live in the hope of one day being with him forever.
Jesus Christ, having entered the sanctuary of heaven once and for all, intercedes constantly for us as the mediator who assures us of the permanent outpouring of the Holy Spirit (Catechism of the Catholic Church 665-667).