The Christian festival of Pentecost, the seventh Sunday after Easter, commemorates the descent of the Holy Spirit upon Christ’s disciples (Acts 2) while they were in Jerusalem celebrating the Feast of Weeks, as described in the Acts of the Apostles (Acts 2:1–31).
In Eastern Christianity, Pentecost also refer to the entire fifty days of Easter through Pentecost inclusive; hence the book containing the liturgical texts is called the “Pentecostarion“.
The term Pentecost comes from the Greek Πεντηκοστή (Pentēkostē) meaning “fiftieth”. It refers to the festival celebrated on the fiftieth day after Passover, also known as the “Feast of Weeks” and the “Feast of 50 days” in rabbinic tradition.
The feast itself lasts three days. The first day is known as “Trinity Sunday”; the second day is known as “Spirit Monday” (or “Monday of the Holy Spirit”); and the third day, Tuesday, is called the “Third Day of the Trinity.”
According to the New Testament writings (Acts 2, 1-11), this event took place in the day of Shavuot, 50 days after the resurrection of Jesus of Nazareth.
Shavuot it is a Jewish holiday that occurs on the sixth day of the Hebrew month of Sivan, meaning it may fall May 15 – June 14. Begins in the 6th day of Sivan (or the Sunday following the 6th day of Sivan in the Karaite tradition) and ends in the 7th (in Israel: 6th) day of Sivan.
Shavuot has a double significance. It marks the all-important wheat harvest in Israel (Exodus 34:22), and it commemorates the anniversary of the day when G-d gave the Torah to the nation of Israel assembled at Mount Sinai.
In 2019, Shavuout starts at sunset in the 8th of June – nightfall and ends at 10th of the June.