The Epiphany, or revelation, of the baby Jesus as the Son of God come into the world, is traditionally celebrated on the 6 January.
As the date of Easter varies from year to year, dates which depend on Easter also vary: for example, Ash Wednesday, and Pentecost. So, when Easter is early, it encroaches on the nine Sundays after Epiphany. However, the number of Sundays after Pentecost expands to compensate for the deficit.