The Venice Film Festival opened today (Wednesday) with an out-of-competition screening of Alfonso Cuarón's Gravity, a space thriller starring George Clooney and Sandra Bullock. It launches 10 days of screenings in which 55 films from 33 countries are due to be screen, 53 of which are world premieres and two international premieres. Of the 20 films selected for the competition seven are from the U.S., two of which are joint productions with Britain. In his review for The Hollywood Reporter, Todd McCarthy, commented: At once the most realistic and beautifully choreographed film ever set in space, Gravity is a thrillingly realized survival story spiked with interludes of breath-catching tension and startling surprise. What sets it aside from other space thrillers, McCarthy noted: no aliens, space ship Battles or dystopian societies, just the intimate spectacle of a man and a woman trying to cope in the most hostile possible environment across a very tight 90 minutes. Justin Chang in Variety called it astonishing ... at once a nervy experiment in blockbuster minimalism and a film of robust movie-movie thrills, restoring a sense of wonder, terror and possibility to the big screen that should inspire awe among critics and audiences worldwide. Robbie Collin in the London Daily Telegraph awarded it five stars, describing the film as a science-fiction thriller of rare and diamond-hard brilliance, And Xan Brooks, the film critic for Britain's Guardian, calls it a brilliantly tense and involving account of two stricken astronauts; a howl in the wilderness that sucks the breath from your lungs.