Image copyright 20th Century Fox Image caption Hidden figures stars Taraji P Henson, Octavia Spencer and Janelle Monae

The stars of upcoming space-race drama Hidden Figures were overcome with emotion at a preview of the film in Toronto.

The movie tells the story of a trio of African-American women working at Nasa whose skills helped put astronaut John Glenn into orbit in 1962.

Actresses Taraji P Henson, Octavia Spencer and Janelle Monae cried as they watched clips ahead of an on-stage Q&A.

Henson apologised afterwards for being so overwhelmed.

"I never got into acting for the accolades. I'm a girl from the hood. I didn't grow up with much, so all I had was dreams and hope," she said.

"This story is so important. Had I known about these women coming up, maybe I would have aspired to be a rocket scientist."

In Hidden Figures, Henson plays mathematician Katherine Johnson, alongside Nasa colleagues Dorothy Vaughan (Spencer) and Mary Jackson (Monae).

Cameron Bailey, the artistic director of the Toronto International Film Festival, said the women had been a "visionary trio who had crossed race and gender lines".

Image copyright 20th Century Fox Image caption Hidden Figures tells the story of three women who worked on Nasa's space programme in the 1960s

Image copyright 20th Century Fox Image caption The film is due to be released in early 2017

The cast also includes Kevin Costner, Kirsten Dunst and Big Bang Theory star Jim Parsons.

Spencer said her character Dorothy "could disassemble anything and put it back together", a skill she had used to fix Nasa's IBM computer.

"No women, not black or white, were mentioned in Apollo 13 or all of these other movies," Spencer said, adding that she was sad that the real Dorothy Vaughan and Mary Jackson had not lived to see their story told on film.

"But I'm excited that Katherine Johnson will," she said, her voice breaking with emotion.

"I just want her to be proud," added Henson.

"People come up to me and they're like, 'Oh, Oscars!' Everybody wants to put on that pressure.

"I don't accept that pressure - I'll let you all say it - but what I was most concerned about was if Katherine would be proud, because she's still alive - this is her story."

The film, directed by Theodore Melfi, is due out in early 2017.

The special screening was followed by an outdoor concert by Pharrell Williams whose songs feature on the soundtrack.

The Toronto International Film Festival runs until 18 September.

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