Hi Aldy, A lantern, typically, has a small, glass door. Only when the door is opened can you reach inside the lantern and light the wick. Here is a link to a photo of a modern version: http://www.ikea.com/PIAimages/73326_PE189971_S5.JPG It is hard to tell without more context from the story, but it sounds like an emergency situation. "To throw open" means to open with urgency. For example, "I could see the gunman approaching, so I throw open the window and jumped out of it". Who knows why the lantern was thrown open? My guess would be to extinguish the flame so as to hide from somebody, and that is why the person has jumped into the room too. Any questions? I hope that I have helped you. Tom

To throw something open (usually a door or window) is to open something fast and completely. In Spanish, I think it would be sort of like "abirir completamente y de golpe" or possible "de par en par." It usually implies a sense of urgency or suddenness. And, really, I think this particular phrase is almost always limited to doors or windows. For example, I don't think you would say you "threw open a drawer" or "threw open the lid to the box." But, others might disagree about that.