18000 Holes In The Universe, Dragonfire by Adam Wallace

It's 1866 and Hester Hitchins' father is missing at sea. Determined to find him, eleven-year-old Hester wins a place at Addington's Nautical Navigation Academy, where she will learn to navigate by the stars. But the academy is just for boys, and what's more, no one seems to be in charge. Bumbling schoolmaster Captain Slingsby doesn't know anything about navigation. Lord Addington is obsessed with building the world's biggest telescope and Lady Addington believes that falling stars are the souls of the dead. With the help of a lodestone, her new friends Pru and Nelson, and a dazzling meteor storm, can Hester set things right - and find her own place in the universe?