This weekend, the Solemnity of the Epiphany falls on a Sunday. Since it is not a holy day of obligation in the US, it used to be celebrated only in monasteries, cathedrals and at daily Mass in parishes. After Vatican II, the American bishops moved it to the closest Sunday. The principle of double-effect is at work here. While moving it to Sunday allowed American Catholics to celebrate this wondrous feast when they would normally be going to church anyway, it also cut the Epiphany from its calendrical mooring of January 6. Thus Twelthnight (Epiphany night) often falls on less or more days than the traditional twelve days of Christmas. This is some cultural loss, except this year when Epiphany and Sunday are the same day. We will truly have the full twelve days of Christmas and Twelthnight on the proper day.
Three things are celebrated at the Epiphany: the visit of the Magi, the Lord's baptism, and the miracle at the wedding feast at Cana. All three are "epiphanies" of Christ: to the gentiles in the person of the Magi; to John the Baptist and the Apostles at the Jordan; and the first miracle of Christ's ministry,recorded by St. John the Divine.
In the Greek Orthodox Church, this feast centers on the Jordan, and usually, wherever possible, the bishop will throw a cross into the nearest river, and young men will dive for it. This can be quite exhilarating, especially in a Russian winter!