Wallpaper Description:

Moveable Feast:
A feast day that falls on the same day of the week each year but which has a date which varies.
Origin:
The Christian moveable (or movable) feasts are those holy days that are set by the date of Easter Sunday.
Over the centuries there have been many disputes over how the date of Easter should be calculated, involving differing views concerning the calendar and religious observance.
This rather complex canonical rule is the one used now in the Christian Church:
Easter Day is the first Sunday following the first ecclesiastical full moon (which is the 14th day of an astronomical new moon) that occurs on or after the day of the Vernal Equinox (March 21st).

Easter sets the date for numerous Christian feasts or fasts. For example:
 Triodion — the period of 70 days before Easter (Eastern and Oriental Orthodox, Greek-Catholic)
 Septuagesima — 63 days (ninth Sunday) before Easter (Pre–Vatican II Calendar)
 Saturday of Souls — 57 days before Easter (Eastern and Oriental Orthodox, Greek-Catholic)
 Sexagesima — 56 days (eighth Sunday) before Easter (Pre–Vatican II Calendar)
 Quinquagesima Sunday — 49 days (seventh Sunday) before Easter (Pre–Vatican II Calendar)
 Shrove Monday — 48 days before Easter. (Western Christianity)
 Shrove Tuesday — 47 days before Easter. (Western Christianity)
 Ash Wednesday — 46 days before Easter. (Strictly speaking, Ash Wednesday is not a feast but a fast, characterised by solemnity and acts of self-denial.) (Western Christianity)
 Triumph of Orthodoxy — 42 days before Easter (Eastern and Oriental Orthodox, Greek-Catholic)
 People's Sunday — 41 days before Easter (in Malta)
 Mothering Sunday — 21 days before Easter (Anglicanism)
 Passion Sunday — 14 days before Easter (Anglicanism)
 Lazarus Saturday — 8 days before Easter (Eastern and Oriental Orthodox, Greek-Catholic)
 Palm Sunday — 7 days before Easter
 Maundy Thursday — 3 days before Easter
 Good Friday — 2 days before Easter (Good Friday is actually a fast rather than a feast day. See Ash Wednesday above.)
 Holy Saturday - 1 day before Easter
 Easter — the date around which the others are placed
 Saint Gregory's Day — 3 days after Easter (in Malta)
 The Octave of Easter or Divine Mercy Sunday, also known as Low Sunday or Quasimodo Sunday — the Sunday after Easter.
 Radonitsa — 8 or 9 days after Easter (Eastern Orthodox)
 Ascension Day — 39 days after Easter
 Pentecost — 49 days after Easter (50th day of Easter)
 Trinity Sunday — 56 days after Easter (Western Christianity)
 All Saints — 56 days after Easter (Eastern and Oriental Orthodox, Greek-Catholic), but in the West this feast is fixed on November 1
 Corpus Christi — 60 days after Easter (Western Christianity)
Although Mardi Gras (Fat Tuesday - also known as Shrove Tuesday) moves around the calendar because it is celebrated 47 days before Easter, it is not technically a moveable feast, because it is not a holiday on any church calendar.