Pope Francis (C) exits his plate upon landing at Havana's international airport, Sept. 19, 2015, on the first leg of a high-profile trip that will also take him to the United States.

The wind carries away Pope Francis' cap as he deplanes in Havana, Cuba, Sept. 19, 2015.

Pope Francis (C-L) is welcomed by Cuban President Raul Castro (C-R) upon landing at Havana's international airport, Sept. 19, 2015, on the first leg of a high-profile trip that will also take him to the United States.

Pope Francis hugs a boy as Cuba's President Raul Castro looks on after landing at the airport in Havana, Cuba, Sept. 19, 2015.

Pope Francis blesses a girl as Cuba's President Raul Castro looks on after landing at the airport in Havana, Cuba, Sept. 19, 2015.

People react after the arrival of Pope Francis outside the airport in Havana, Cuba, Sept. 19, 2015.

People watch as Pope Francis is shown on television as he arrives in Havana, Cuba, Sept. 19, 2015 in Santiago de Cuba, Cuba.

Pope Francis meets with former Cuban President Fidel Castro at Castro's resident in Havana, Sept. 20, 2015.

Pope Francis arrives at Revolution Square in Havana, Cuba, Sept. 20, 2015.

Pope Francis arrives to the Plaza of the Revolution to celebrate Mass in Holguin, Cuba, Sept. 21, 2015.

Cuba's President Raul Castro, left, and First Vice President Miguel Diaz-Canel, applaud as Pope Francis arrives at the Plaza of the Revolution to celebrate a Mass, in Holguin, Cuba, Sept. 21, 2015.

Pope Francis is greeted by Cuba's President Raul Castro as he arrives to celebrate Mass in the Plaza of the Revolution, in Holguin, Cuba, Sept. 21, 2015. Francis traveled to Cuba's fourth-largest city, Holguin, and celebrated a Mass where Cuban rhythms mixed with church hymns under a scorching tropical sun.

Pope Francis holds a Mass in the Plaza de la Revolution on Sept. 21, 2015 in Holguin, Cuba.

Yulieisis Medreno, 24, smiles after checking the picture she took of Pope Francis on his way to the Hill of the Cross in Holguin, Cuba, Sept. 21, 2015.

Pope Francis conducts a blessing of the city from the Loma de la Cruz, or the Hill of the Cross on Sept. 21, 2015 in Holguin, Cuba.

People wait for the arrival of Pope Francis who will lead Mass at the sanctuary of the Virgin of Charity, or Our Lady of El Cobre, in El Cobre, Cuba, Sept. 22, 2015.

Members of the Armed Forces Full Honor Cordon from the Military District of Washington roll up the red carpet after a practice run for the arrival of Pope Francis, Sept. 22, 2015, at Andrews Air Force Base in Md.

People watch as Pope Francis arrives from Cuba, Sept. 22, 2015 at Joint Base Andrews, Md.

The plane carrying Pope Francis arrives at Andrews Air Force Base, Md., Sept. 22, 2015.

Clergy brace for the wind as they stand along the red carpet on the tarmac at Andrews Air Force Base, Md., Sept. 22, 2015, as the plane carrying Pope Francis arrives.

Pope Francis takes off his cap while stepping off an airplane after arriving from Cuba, Sept. 22, 2015 at Joint Base Andrews, Md.

Pope Francis is greeted by President Barack Obama, first lady Michelle Obama, Vice President Joe Biden and other political and Catholic church leaders after arriving from Cuba, Sep. 22, 2015 at Joint Base Andrews, Md.

Pope Francis is escorted by President Barack Obama, as he greets other political and Catholic church leaders, after arriving from Cuba on Sept. 22, 2015 at Joint Base Andrews, Md.

Pope Francis departs in a Fiat after arriving from Cuba, Sept. 22, 2015 at Joint Base Andrews, Md.

Pope Francis arrives at the Vatican Embassy in Washington, Sept. 22, 2015.

Cardinal Donald Wuerl, Archbishop of Washington, speaks with school children after Pope Francis arrived at the Apostolic Nunciature, the Vatican's diplomatic mission in the heart of Washington, Sept. 22, 2015.

A man holds up a Papal flag as he waits for Pope Francis departure from the Apostolic Nunciature, the Vatican's diplomatic mission in Washington, Sept. 23, 2015.

A man kisses Pope Francis while he greets well-wishers outside the Apostolic Nunciature in Washington, Sept. 23, 2015, prior to his departure to the White House.

Children of parents who work at the Lithuanian Embassy take selfies with Pope Francis as he departs the Apostolic Nunciature in Washington, Sept. 23, 2015.

Pope Francis greets well-wishers as he departs the Apostolic Nunciature, the Vatican's diplomatic mission in Washington, Sept. 23, 2015.

People wait for the arrival of Pope Francis at the White House on Sept. 23, 2015 in Washington, DC.

President Barack Obama and Pope Francis wave at the end of an arrival ceremony at the White House on Sept. 23, 2015 in Washington, DC.

In this photo provided by L'Osservatore Romano, President Barack Obama meets with Pope Francis at the White House in Washington, Sept. 23, 2015.

President Barack Obama walks with Pope Francis down the West Wing Colonnade to a meeting in the Oval Office of the White House in Washington, Sept. 23, 2015.

President Barack Obama talks with Pope Francis in the Oval Office of the White House in Washington, Sept. 23, 2015.

In this photo provided by L'Osservatore Romano, Pope Francis and first lady Michelle Obama pet the Obama's dogs Bo and Sunny as President Barack Obama looks at the White House in Washington, Sept. 23, 2015.

Pope Francis stands at the altar of the Blessed Sacrament Chapel for a private prayer before participating in the Midday Prayer Service at the Cathedral of St. Matthew, Sept. 23, 2015 in Washington.

Pope Francis attends the Midday Prayer Service at the Cathedral of St. Matthew on September 23, 2015 in Washington.

Pope Francis places his hand on the forehead of a young woman in a wheelchair as he arrives at the Apostolic Nunciature in Washington, Sept. 23, 2015.

Pope Francis waves to the crowd before conducting Mass and the Canonization of Blessed Junipero Serra at the Basilica of the National Shrine of the Immaculate Conception, Sept. 23, 2015 in Washington.

Pope Francis arrives inside the Basilica of the National Shrine of the Immaculate Conception in Washington, Sept. 23, 2015.

Pope Francis Celebrates Mass Of Canonization on the East Portico of the Basilica of the National Shrine of the Immaculate Conception on Sept. 23, 2015 in Washington.

People gather in front of the US Capitol in Washington, Sept. 24, 2015, before Pope Francis addresses a Joint Session of Congress on the third day of his six-day visit to the US.

Pope Francis gives a thumbs-up while greeting school children before departing the Apostolic Nunciature, the Vatican's diplomatic mission in Washington, Sept. 24, 2015, en route to the Capitol to address a joint meeting of Congress.

Speaker of the House John Boehner speaks with Pope Francis in the U.S. Capitol building before the Pontiff speaks to a joint meeting of Congress, Sept. 24, 2015, in Washington.

Pope Francis pauses in front of a sculpture of Spanish-born Junipero Serra, the Franciscan Friar known for starting missions in California, in Statuary Hall at the U.S. Capitol in Washington, Sept. 24, 2015.

Pope Francis arrives to address the joint session of Congress, Sept.24, 2015, in Washington.

A nun listens as Pope Francis addresses a joint meeting of the U.S. Congress in the House Chamber of the U.S. Capitol, Sept. 24, 2015, in Washington.

Pope Francis, accompanied by members of Congress, waves to the crowd from the Speakers Balcony on Capitol Hill in Washington, Sept. 24, 2015, after addressing a joint meeting of Congress inside.

Congressional staffers and guests strain to view and photograph the departure of Pope Francis in his Fiat 500L, on Capitol Hill in Washington, Sept. 24, 2015, after his speech before a joint meeting of Congress.

Pope Francis arrives for his departure from Washington, en route to New York on Sept. 24, 2015 in Joint Base Andrews, Md.

Pope toys are displayed on the walls on Sept. 24, 2015 in New York.

A New York City police officer searches nuns outside St. Patrick's Cathedral prior to the arrival of Pope Francis in New York, Thursday Sept. 24, 2015.

Pope Francis makes his way up Fifth Avenue toward St. Patrick's Cathedral in the popemobile Sept. 24, 2015 in New York.

Nuns celebrate as they wait for the arrival of Pope Francis at St Patrick's Cathedral in New York on Sept. 24, 2015.

Pope Francis walks down the aisle of St. Patrick's Cathedral in New York, as he arrives to celebrate vespers, Sept. 24, 2015.

Pope Francis speaks during evening prayer service at St. Patrick's Cathedral in New York, Sept. 24, 2015.

Pope Francis arrives for a plenary meeting of the United Nations Sustainable Development Summit 2015 at United Nations headquarters, New York, Sept. 25, 2015.

Pope Francis speaks at the United Nations General Assembly in New York on Sept. 25, 2015.

A miniature Vatican flag is placed at the 9/11 memorial where Pope Francis attend a multi-faith prayer service in New York on Sept. 25, 2015.

Pope Francis pauses during a visit to Ground Zero on Sept. 25, 2015 in New York.

Pope Francis, center left, reads during a multi-religious service at the 9/11 Museum, Sept. 25, 2015 in New York.

People make their way in huge lines on the western edge of New York City's Central Park, waiting to get in to see Pope Francis' precession through the park on Sept 25, 2015.

Wilfredo Cedron displays a specially made hat near New York's Central Park where thousands of people were waiting in line to get in to see Pope Francis' precession through the park on Sept. 25, 2015.

Pope Francis rides in the Popemobile through New York City's Central Park on Sept. 25, 2015.

Fans flock to view Pope Francis' motorcade and Popemobile as it proceeds through Central Park in New York City on Sept. 25, 2015.

A policeman stands guard near the Madison Square Garden where Pope Francis will attend a prayer mass in New York on Sept. 25, 2015.

Pope Francis is shown on three large video monitors as he celebrates high Mass at Madison Square Garden on Sept. 25, 2015 in New York City.

Pope Francis is greeted by nuns from the Monastery of the Precious Blood who presented the pontiff with a gift of flowers before boarding his flight from New York en route to Philadelphia on Sept. 26, 2015.

Pope Francis kisses and blesses Michael Keating, 10, of Elverson, Pa. after arriving in Philadelphia and exiting his car when he saw the boy, Sept. 26, 2015, at Philadelphia International Airport. Keating has cerebral palsy and is the son of Chuck Keating, director of the Bishop Shanahan High School band that performed at Pope Francis' airport arrival.

Pilgrims wave cardboard cutouts of Pope Francis as they gather outside the Cathedral Basilica of Saints Peter and Paul, ahead of the papal mass this morning in Philadelphia, Sept. 26, 2015.

Pilar Cedeno, of Hackensack, N.J., prays as Mass conducted by Pope Francis is broadcast to crowds on the Benjamin Franklin Parkway from inside the Cathedral Basilica of Saints Peter and Paul, Sept. 26, 2015, in Philadelphia.

Pope Francis celebrates mass at the Cathedral Basilica of Saints Peter and Paul in Philadelphia, on Sept. 26, 2015.

Pope Francis greets the crowd from the Pope Mobile as he arrives at Independence Mall on Sept. 26, 2015 in Philadelphia..

Pope Francis kisses a baby as he arrives to Independence Mall, Sept. 26, 2015, before delivering a speech in front of Independence Hall, in Philadelphia.

Pope Francis delivers remarks at Independence Hall in Philadelphia on, Sept. 26, 2015.

People react and a women in center wipes a tear as Pope Francis speaks in front of Independence Hall, Saturday, Sept. 26, 2015 in Philadelphia.

Pope Francis has his head covered by his vestments as he delivers remarks on the theme "We Hold These Truths," a quote from the U.S. Declaration of Independence, in front of Independence Hall in Philadelphia, Sept. 26 2015.

Pope Francis makes his way to the Festival of Families along Benjamin Franklin Parkway in Philadelphia on Sept. 26, 2015. (Eric Thayer/The New York Times via AP, Pool)

Bellatrix, right, has her costume adjusted by owner Ashley Spann while posing for photos for pedestrians with Addie, left, and owner Emily Mariani, right, outside the Pennsylvania Convention Center, host of the World Meeting of Families conference, Sept. 25, 2015, in Philadelphia.

People react as Pope Francis greets them from the pope mobile during a parade as he visits the Festival of Families in Philadelphia on Sept. 26, 2015. (Alex Wong/Pool Photo via AP)

Pope Francis is received as he visits the Festival of Families in Philadelphia on Sept. 26, 2015.

American singer Aretha Franklin sings as Pope Francis and others listen during the World Meeting of Families festival in Philadelphia, Sept. 26, 2015.

Pope Francis speaks at the Festival of Families in Philadelphia on Sept. 26, 2015. (Eric Thayer/The New York Times, Pool)

Pope Francis touches a woman in a wheelchair after he addressed a gathering in Saint Martin's Chapel at St. Charles Borromeo Seminary, Sept. 27, 2015, in Wynnewood, Pa.

Pope Francis greets seminarians as he walks the loggia to his address to the Bishops at St. Martin of Tours Chapel at Saint Charles Borromeo Seminary, Sept. 27, 2015 in Wynnewwod, Pa.

Inmate David Hernandez, 39, of North Philadelphia, prays during Pope Francis' visit to Curran Fromhold Correctional Facility in Philadelphia, Sept. 27, 2015.

Pope Francis shakes hands with an inmate as he meets with prisoners at Curran-Fromhold Correctional Facility in Philadelphia, Sept. 27, 2015.

An unidentified child, who was carried from the crowd, touches Pope Francis' face during a parade on his way to celebrate Sunday Mass on the Benjamin Franklin Parkway in Philadelphia, Sept. 27, 2015.

Dana and Daniel Madden's daughter, Quinn, met Pope Francis in Philadelphia on Sept. 26, 2015.

Spectators pray as they listen to the papal Mass during the World Meeting of Families on Sept. 27, 2015 in Philadelphia.

Pope Francis' mass is pictured in Philadelphia on Sept. 27, 2015.

Pope Francis reaches to bless a little girl as he accepts gifts from her family during mass at the World Meeting of Families at Benjamin Franklin Parkway on Sept. 27, 2015 in Philadelphia.

Pope Francis' mass is pictured in Philadelphia on Sept. 27, 2015.

Pope Francis greets volunteers from the World Meeting of Families at Philadelphia International Airport in Philadelphia before departing for Rome on Sept. 27, 2015.

Vice President Joe Biden bids farewell to Pope Francis before he boards his plane in Philadelphia on Sept. 27, 2015.

Pope Francis boards his plane as he prepares to depart Philadelphia International Airport in Philadelphia on Sept. 27, 2015.

Pope Francis is pictured at the airport in Philadelphia, prior to his departure on Sept. 27, 2015.