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(CNN) -- Warner Bros.' $100 million Alfonso Cuarón-directed thriller Gravity blasted off on its opening weekend at the box office, scoring a stunning $55.6 million from 3,575 theaters. The sci-fi title, which stars Sandra Bullock and George Clooney, set a new October opening weekend record, surpassing Paranormal Activity 3's $52.6 million debut in 2011.

Gravity also marks the best-ever debut for both of its stars, beating Bullock's $39.1 million start for this summer's The Heat (talk about having a great year at the box office!) and Clooney's $42.9 million debut for Batman & Robin in 1997. And to put a cherry on top of Warner Bros.' incredible weekend, audiences issued Gravity an excellent "A-" CinemaScore grade, which will yield great word-of-mouth for weeks to come.

The film played to a much broader audience than most young-male-dominated sci-fi films. Crowds were 54 percent male and 46 percent female, and 59 percent were above the age of 35. 3-D showings accounted for a whopping 80 percent of the film's weekend gross (bucking the downward trend 3-D has faced this year and proving that audiences will pay for the format if they feel it's worth it). IMAX tickets made up 20 percent of revenue — because if there's one thing that looks great on a big screen, it's outer space.

Cloudy With a Chance of Meatballs 2 dropped 37 percent in its second weekend to $21.5 million, which gives the animated title a $60.6 million total after 10 days. Sony spent $78 million on the saucy sequel and wisely scheduled it away from other family competition, which should allow it to thrive throughout October. (By comparison, films like Turbo and The Smurfs 2 got choked out this summer while competing with each other and Despicable Me 2 and Monsters University.) The next animated film to arrive in theaters, Free Birds, won't come out until Nov. 1.

Ben Affleck and Justin Timberlake faltered in third place with their new crime drama Runner Runner, which earned a weak $7.6 million in its first three days. Both stars are hotter than ever: Affleck, after winning an Oscar for Argo and landing the Batman role in Warner Bros.' upcoming Man of Steel sequel, and Timberlake, after hitting No. 1 with his comeback album The 20/20 Experience, the sequel to which is projected to be the No. 1 album this week. But nothing about Runner Runner inspired crowds to check it out in theaters. Audiences issued the poorly reviewed film, which cost Fox about $30 million, a weak "C" CinemaScore grade.

Prisoners and Rush made up the rest of the Top 5. Prisoners fell 48 percent to $5.7 million, giving the Hugh Jackman vehicle a $47.9 million total against a $46 million budget. The film earned excellent reviews, but has had trouble holding on to audiences due to the arrival of Rush, Don Jon, and Gravity — three well-reviewed dramas attracting attention. Fortunately, Prisoners is holding on better than one of those films, Rush, which fell 56 percent this weekend to $4.4 million. The Formula One racing drama starring Chris Hemsworth and directed by Ron Howard has now earned $18.1 million total and will fall short of its $38 million budget.

1. Gravity -- $55.6 million

2. Cloudy With a Chance of Meatballs 2 -- $21.5 million

3. Runner Runner -- $7.6 million

4. Prisoners -- $5.7 million

5. Rush -- $4.4 million

Check back next weekend for full box office coverage of new releases Machete Kills and Captain Phillips.

See the original story at EW.com.