When Cybermen and Daleks invaded, she and the Doctor opened the void to send them back. One of the levers was not in the correct position, so Rose moved it, but she got sucked in. Just in time, her "father" saved her, transporting her to the parallel universe from which he came. For clarification, watch "Army of Ghosts" and "Doomsday".
- Just a note, she did not end up in a different dimension. It was a parallel universe.