Pope Benedict XVI, riding in the Popemobile, makes his entrance into the stadium. (AP photo by Pablo Martinez Monsivais)

9:58 a.m.

Pope Benedict has processed into the stadium and to the altar, wearing red vestments and a gold miter and wearing the white, woolen stole, or pallium, of an archbishop.  He has just scooped incense into the censor and is incensing the altar for the start of the mass, which will last about 90 minutes. He will deliver a homily shortly, and is expected to touch on several themes including the clergy sex abuse scandals, which he has addressed on the two previous days of his visit. 

9:40 a.m.

The Pope has arrived! About seven minutes ago the crowd was asked to take their seats, and moments ago the white "popemobile" made its way into the infield of Nationals' Park. Pope Benedict has the windows down, waving as he did yesterday entering the grounds of the Shrine of the Immaculate Conception.

Many in the crowd are waving gold and white papal flags, and a choir somewhere is singing as he circles infield and approaches the altar. 

Catholic clergy walk on the field. (AP photo by Susan Walsh)

Pope Benedict XVI starts the second full day of visit to the United States with a mass at Nationals' Park baseball stadium in Washington, D.C.. It starts at 10 a.m., but the stadium is already filling up.

The outfield is home to a to very large white and gold superstructure over the moden altar where Benedict will celebrate the mass, and behind the altar there's a large and very traditional wooden crucifix. The structure appears to offer some protection against rain, but that won't be necessary today: There's not a cloud in sight - just security helicopters whirling over the stadium.

The crowd, which is expected to fill all the 47,000 available seats, is being treated to the music of live choirs interspersed with videos generated by various dioceses and archdioceses greeting Benedict. The Philadelphia Archdiocese's video flashed on the Jumbotron about 20 minutes ago: It features lots of cute kids standing in front of Philadelphia landmarks, but we can't hear it in the glass-enclosed press gallery.

I wonder if the Washington Nationals will keep the white picket fence and shrubs planted around the baselines. Might get in the way of an infield double.

AP Photo by Gerald Herbert

To give a sense of the early scene, here's an Associated Press photograph of three Little Sisters of the Poor, who were among the first to arrive this morning for the Papal Mass in Washington, D.C. Sister Rose Marie, Sister Imelda and Sister Florine would be joined by more than 40,000 other people to see and hear Pope Benedict XVI in Nationals Park.