“Modern Family” star Jesse Tyler Ferguson is a guest judge on “Project Runway” (Lifetime at 9 p.m.), as he shows up to promote Tie the Knot — founded by Ferguson and his husband, Justin Mikita — in which proceeds from the sale of designer bow ties benefit foundations that support marriage equality. In the episode, the designers must incorporate a bow tie from the collection into their designs.

It’s almost the halfway point on this season’s “Big Brother” (CBS at 9), which means the contestants must be extra careful on eviction night because their exiled housemates may soon be the jurors who will award someone $500,000 at the end of the season.

Original movie “Invasion Roswell” (Syfy at 9) airs near the anniversary of the famous July 1947 incident, in which some suspect that the government covered up evidence of an alien crash-landing in Roswell, N.M. The movie looks at what happens decades later, when the aliens come back to invade earth, and the only people trained to stop them are retired commandos who were originally trained to deal with an alien invasion.

A Middle Eastern diplomat is poisoned on “Burn Notice” (USA at 9), so the team searches a lab for a cure; meanwhile, Madeline thinks she’s being followed.

Anne Burrell auditions four chefs for a job at a restaurant each week on “Chef Wanted With Anne Burrell” (Food Network at 10), and in this episode, a position is up for grabs at a Le Cirque outpost in Abu Dhabi, United Arab Emirates.

Shark Week continues on Discovery with “Sharkpocalypse” (at 9), about the contrast between an increased number of shark attacks and a low number of sharks (because of shark finning). Later, “Alien Sharks of the Deep” (at 10) looks at some of the more bizarre members of the breed.

Briggs and Bello are getting along on “Graceland” (USA at 10), but that could all change with a dangerous situation involving a cartel.

Actresses Vanessa Hudgens and Ashley Tisdale, who bonded while starring in Disney’s “High School Musical” franchise, star in their own special, “Vanessa & Ashley: Inner Circle” (E! at 10), which appears to be the equivalent of listening in on two friends’ personal conversation — while they promote their movies, of course.

“The Tonight Show With Jay Leno” (NBC at 11:35) hosts actor Robin Williams, entrepreneur Mark Cuban and singer Gavin DeGraw.

Actor Harrison Ford, actress Keri Russell and musical guest Joan Jett are on “Jimmy Kimmel Live” (ABC at 11:35).

— Emily Yahr