Space/Is Air/Sandbox

Space Is Air when a work treats spacecraft as if they were aircraft; they bank into turns, keep their engines firing at all times, and may even have wings built into their design. This is primarily because audiences are more familiar with how airplanes work than they are how spaceships work; thus, creators treat spaceships as if they are simply airplanes in space instead of using realistic physics, in order to avoid confusing the audience. This isn't necessarily a bad thing -- after all, it can be used to great effect to make things look really cool -- but it does push things down toward the softer end of Mohs Scale of Sci Fi Hardness.

The way airplanes work is dependent on the fact that they're travelling through the atmosphere. Wings provide lift, flaps and rudders can reorient the plane by redirecting airflow, and their engines must be on constantly in order to counteract the effects of friction. Because space is a vacuum, none of these things apply to spaceships -- wings and flaps are useless, and the engine only needs to be on when the ship is changing speed or direction. This means that spacecraft must have dedicated thrusters to reorient themselves, and change direction in sharp bursts rather than gradually. If you see a spaceship changing direction without using maneuvering rockets, or making wide, sweeping turns, then that's because Space Is Air.

See also Space Is an Ocean, Space Friction, and Space Does Not Work That Way.