Divine Mercy Novena is a "prayerful devotion," according to CatholicFire.blogspot.com.
The Divine Mercy Novena begins today, Friday, April 2 (and always begins on Good Friday). This year Divine Mercy Sunday will be Sunday, April 11, 2010.
Divine Mercy Sunday, or The Feast of the Divine Mercy, is observed on the octave of Easter, meaning one week after Easter Sunday. The feast is meant to celebrate the "fullness of Christ's Resurrection," according to St. Louis Review.com.
According to CatholicFire.blogspot.com, the late Pope John Paul II called the second Sunday of Easter (the week after Easter Sunday) to be Divine Mercy Sunday. Ten years ago, he made this proclamation in connection with Sister Faustina Kowalska's canonization. The Sister was a Polish nun who had visions of Christ and out of those visions came the Divine Mercy devotion.
St. Faustina died at the age of 33, in 1938. And it is said that Christ revealed to her a powerful prayer called the Chaplet of Divine Mercy. St. Faustina wrote in her diary that Jesus said to her, "On each day of the novena you will bring to My heart a different group of souls and you will immerse them in this ocean of My mercy ... On each day you will beg My Father, on the strength of My passion, for the graces for these souls."
There is a list of the different "souls" that are to be prayed for on each day. You can find a complete list here. Day 3, Easter Sunday, "All devout and faithful souls," are to be prayed for. On Day 4, Easter Monday, "Those who do not believe in Jesus those who do not yet know Him," shall be acknowledged through prayer.
I'd never heard of the Divine Mercy Sunday or Novena until doing this research today. Interesting stuff!