The Ascension of Christ is celebrated, well it used to be celebrated on Thursday, this Sunday. My diocese celebrates it on Sunday and other diocese still celebrate it on Thursday. So today, being the original day known as Ascension Thursday, here is a special post. I posted this cartoon a while back, as you can see from the date on the picture, but it is appropriate for today.
There are some theologians who speculate that Christ's ascension into Heaven was partly so that His sacrifice would be completed, this idea ties in well with the Mass being the Heavenly Liturgy. I am no expert on this, so don't take my word on it. It is just something I've heard discussed.
The CCC says the following about the Ascension:
"HE ASCENDED INTO HEAVEN AND IS SEATED AT THE RIGHT HAND OF THE FATHER"
659 "So then the Lord Jesus, after he had spoken to them, was taken up into heaven, and sat down at the right hand of God."532 Christ's body was glorified at the moment of his Resurrection, as proved by the new and supernatural properties it subsequently and permanently enjoys.533 But during the forty days when he eats and drinks familiarly with his disciples and teaches them about the kingdom, his glory remains veiled under the appearance of ordinary humanity.534 Jesus' final apparition ends with the irreversible entry of his humanity into divine glory, symbolized by the cloud and by heaven, where he is seated from that time forward at God's right hand.535 Only in a wholly exceptional and unique way would Jesus show himself to Paul "as to one untimely born", in a last apparition that established him as an apostle.536
660 The veiled character of the glory of the Risen One during this time is intimated in his mysterious words to Mary Magdalene: "I have not yet ascended to the Father; but go to my brethren and say to them, I am ascending to my Father and your Father, to my God and your God."537 This indicates a difference in manifestation between the glory of the risen Christ and that of the Christ exalted to the Father's right hand, a transition marked by the historical and transcendent event of the Ascension.
661 This final stage stays closely linked to the first, that is, to his descent from heaven in the Incarnation. Only the one who "came from the Father" can return to the Father: Christ Jesus.538 "No one has ascended into heaven but he who descended from heaven, the Son of man."539 Left to its own natural powers humanity does not have access to the "Father's house", to God's life and happiness.540 Only Christ can open to man such access that we, his members, might have confidence that we too shall go where he, our Head and our Source, has preceded us.541
662 "And I, when I am lifted up from the earth, will draw all men to myself."542 The lifting up of Jesus on the cross signifies and announces his lifting up by his Ascension into heaven, and indeed begins it. Jesus Christ, the one priest of the new and eternal Covenant, "entered, not into a sanctuary made by human hands. . . but into heaven itself, now to appear in the presence of God on our behalf."543 There Christ permanently exercises his priesthood, for he "always lives to make intercession" for "those who draw near to God through him".544 As "high priest of the good things to come" he is the center and the principal actor of the liturgy that honors the Father in heaven.545
663 Henceforth Christ is seated at the right hand of the Father: "By 'the Father's right hand' we understand the glory and honor of divinity, where he who exists as Son of God before all ages, indeed as God, of one being with the Father, is seated bodily after he became incarnate and his flesh was glorified."546
664 Being seated at the Father's right hand signifies the inauguration of the Messiah's kingdom, the fulfillment of the prophet Daniel's vision concerning the Son of man: "To him was given dominion and glory and kingdom, that all peoples, nations, and languages should serve him; his dominion is an everlasting dominion, which shall not pass away, and his kingdom one that shall not be destroyed."547 After this event the apostles became witnesses of the "kingdom [that] will have no end".548
665 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).