Today, the 1st Sunday after Easter Sunday and the 2nd Sunday of Easter in the Catholic Church, is also "Divine Mercy Sunday". It was on the 2nd Sunday of Easter in 2000 that Pope John Paul II decreed that this Sunday should be designated as "Divine Mercy Sunday". This is a day that celebrates the merciful love of God shining through the whole Easter Triduum and the whole Easter mystery. It is a day of declaration of reparation for all sin, thus the Day of Atonement. (thedivinemercy.org)
The Second Sunday of Easter was already called "Octave Sunday" and was a solemnity. "...the title 'Divine Mercy Sunday' does highlight and amplify the meaning of the day. In this way, it recovers an ancient liturgical tradition, reflected in a teaching attributed to St. Augustine about the Easter Octave, which he called 'the days of mercy and pardon,' and the Octave Day itself 'the compendium of the days of mercy.' "
Today also just happens to be the Beatification of Pope John Paul II. What an amazing man he was! He was arguably our most athletic pope: He hiked, skied, played soccer, and was very "outdoorsy". After the assassination attempt, he went to the prison and forgave the man who shot him. This man was a professional assassin, and, when he saw the Pope, he asked him why he wasn't dead. The shots were at close range, and there were 3 fired. He had one of the bullets placed in the crown of the Virgin Mary at Fatima, Portugal, because he gave her the credit for saving him. (One of the bullets barely missed his heart.) The attempt happened on the feast of Our Lady of Fatima. He was the first pope to pray in a synagogue, to enter a mosque in a Muslim country, and to preside in a meeting that involved all of the world's major religious heads. He stuck to his guns on Catholic teachings and refused to budge.