“The Osmonds 50th Anniversary Reunion” (7 p.m., PBS): This special, taped at the Orleans

“The Osmonds 50th Anniversary Reunion” (7 p.m., PBS): This special, taped at the Orleans hotel in Las Vegas, brings together seven singing members of the Osmond family — Alan, Donny, Jay, Jimmy, Marie, Merrill and Wayne — to perform some of their hits in concert. The program includes vintage photos and film clips, as well as celebrity cameos. Singer Andy Williams, whose 1960s variety show featured the Osmond Brothers, also appears.

“Quest for the Lost Ark” (8 p.m., History Channel): Some may be tempted to break out the fedoras and leather whips when History Channel airs this two-hour special that follows the theories of professor Tudor Parfitt, billed as “the British Indiana Jones.” This special documents Parfitt’s efforts to discover the story surrounding the Ark of the Covenant and its final resting place. He encounters politicians, mystics and other challenges and dangers on his quest to solve an ancient biblical mystery.

“Oprah’s Big Give” (9 p.m., ABC): You just weren’t generous enough, so ... you’re fired! Give it up for “Oprah’s Big Give,” a sort of altruistic twist on “The Apprentice” that sends competing do-gooders on missions to surprise needy people with help. And get it done in only five days. At the end of each episode, the contestants are judged on how well they pulled off that week’s assignment. The one who comes up short gets sent home. Then, at the end of the eight-week series, there’ll be the biggest surprise of all: The contestant deemed the “biggest giver” will be shocked to receive a $1 million prize. “The biggest giver becomes the biggest winner,” explains Oprah. “Oprah Winfrey Show” regular Nate Berkus is host. The panel of “expert judges” consists of “Naked Chef” Jamie Oliver, NFL superstar Tony Gonzalez, and Malaak Compton-Rock, wife of comedian Chris Rock who’s involved in humanitarian work. The 10 contestants at the start of the series include a U.S. veteran of the Iraq War, a 22-year-old dot-com millionaire, a former girl-gang member, a TV producer who’s a paraplegic and a beauty pageant queen.

“Human Body: Pushing the Limits” (9 p.m., Discovery Channel): Fun facts about your body: It can withstand six times its weight when running and 12 times its weight when squatting. The human rib cage is built so tough that it can support half a ton while still protecting vital organs. For more cool facts, catch a four-hour miniseries, “Human Body: Pushing the Limits,” which explores physical and mental feats of the body under the most challenging circumstances. In the first two hours, airing Sunday at 9 p.m., human muscles, ligaments, joints and bones are seen at work as a man survives the fury of a tornado, or is pinned beneath a half-ton boulder. Then the power of sight gets a close look, with a lifeguard capable of spotting someone in trouble among thousands, and a firefighter battling thick black smoke to see his way to safety. The concluding two parts air March 9.

“Unhitched” (9:30 p.m., Fox): The Farrelly brothers (”There’s Something About Mary” and “Dumb & Dumber”) bring their twisted brand of humor to television with “Unhitched.” It’s a sitcom that follows a group of newly single friends in their 30s as they struggle to re-enter the dating scene. Craig Bierko and Rashida Jones head the cast.

“Dirt” (10 p.m., FX): Courteney Cox is back spilling “Dirt” as Lucy Spiller, the unrelenting editor-in-chief of an L.A. celebrity tabloid named Dirt Now, as this FX drama starts its second season of guilty pleasures. Picking up where it left off, “Dirt” finds Lucy bleeding and unconscious after an attack by actress Julia Mallory (Laura Allen), whose career was destroyed by the magazine. Primo paparazzo Don Konkey (Ian Hart) struggles to overcome his schizophrenia through medication as he reels from news of best friend Lucy’s assault. Holt McLaren (Josh Stewart) ascends to A-list stardom after ditching Julia. And Willa McPherson (Alexandra Breckenridge) ends her affair with Dirt Now publisher Brent Barrow (Jeffrey Nordling) as a sadder-but-wiser reporter on Lucy’s staff.

“That’s Amore” (10 p.m., MTV): This spin-off from “A Shot with Tila Tequila” has reject Domenico Nesci searching for love, but finding it in all the wrong places.