In Brief CCC 665
© Libreria Editrice Vaticana Source: vatican.va
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).
Read the full chapter 2. I Believe in Jesus Christ, the Only Son of God ¶422–682