Mars attacked — in 1913

“What if?” Literary scholars say that question has driven science fiction since time immemorial, and the made-forTV movie The Great Martian War poses a doozy: What if Mars invaded Earth in 1913?

The Great Martian War isn’t a sci-fi B picture exactly. It airs on History and has been carefully crafted to look, sound and feel like a historical documentary, complete with grainy archival footage, witness testimony from aging survivors and the analysis and deconstruction of present-day experts.

The Great Martian War combines computer-generated images of alien invaders and film footage from the First World War to create the illusion that a Martian invasion actually happened. Think of it as Orson Welles’s The War of the Worlds crossed with Woody Allen’s Zelig, dressed up as a historical documentary. (9 p.m., History)

If Sheldon Cooper were a real person, and if The Great Martian War were based on real events, Sheldon would no doubt be a true believer. Fiction rules his world, though. On a new episode of The Big Bang Theory called The Discovery Dissipation, Sheldon (Jim Parsons) spirals into depression after his recent contribution to science is disproven as bunk. (8 p.m., CTV, CBS)

Nathan’s (Will Arnett) midlife fears are realized on The Millers, as he learns his sister was their father’s favourite all along. He handles the revelation with typical grace and maturity, by filling his parents in on some of his sister’s childhood secrets. Classy to the end ... (8:30 p.m., Global, CBS)

Glee pulls off a nifty trick of its own, with a Christmas episode, Previously Unaired Christmas, that host Sue Sylvester (Jane Lynch) insists was pulled from the air last year.

It’s a holiday special, in which the New Directions show chorus stages an Nativity musical, with all the attendant controversy. Just like Christmas itself. (9 p.m., Global, Fox)