“The Wonder Pets” (7 p.m., Nick Jr.): The Wonder Pets go to England to save their

“The Wonder Pets” (7 p.m., Nick Jr.): The Wonder Pets go to England to save their favorite rock band — the Beetles.

“Gossip Girl” (8 p.m., The CW):OMG! “Gossip Girl” is back with a fresh episode tonight, and we’re all wondering how Blair will adjust to life now that she has been dethroned as Queen Bee. Meanwhile, just how long can Serena keep Dan in the dark about her past?

“American Experience” (9 p.m., PBS): A poignant, inspiring story for the start of baseball season: Roberto Clemente is profiled by “American Experience.” Born in a poor rural barrio in Puerto Rico, he was drafted by the Brooklyn Dodgers in 1954 (and met with 1950s-era racism), then went on to become baseball’s first Latino superstar. In his 18 seasons with the Pittsburgh Pirates, he led the team to two World Series championships and won four National League batting titles. In his final turn at bat for the 1972 season, he got his 3,000th career hit. But by then he was also focusing on humanitarian causes. The last day of 1972, he boarded a DC-7 aircraft with relief supplies for survivors of a catastrophic earthquake in Nicaragua. Shortly after takeoff, the overloaded aircraft crashed, cutting short the life of the 38-year-old baseball legend and budding statesman. Clemente’s wife, Vera, hall of famer Orlando Cepeda and former teammates are among those who appear in the one-hour portrait.