According to the New Testament, Jesus Christ met with his disciples several times during the 40 days after his resurrection, in order to instruct them on how to carry out his teachings. After 40 days he took them to the Mount of Olives, where the disciples saw how he ascended to heaven, after announcing that he would send them the Holy Spirit.
Ascension Day is traditionally celebrated on "Thursday." However, in some places, it is celebrated on the following Sunday. On this day we celebrate the definitive triumph of Jesus, who left the Father and now returns to the place where his Father is. He has told us that he has a place prepared for us, so that where he is, those of us who have believed in his Word may also be.