Tausendstern Horizon simulates an aircraft's artificial horizon. In planes an artificial horizon is used to indicate the attitude of the craft relative to the horizon. Now you can have the same for your iPhone or iPod Touch, rendered in realtime in photo-realistic OpenGL. Corresponding to the roll and pitch angles of an aircraft the central sphere indicates the tilt of the device relative to gravity for the Z axis (from your eye to the display of the device) and the X axis (from the left side of the display to the right when the device is in portrait orientation). Changes around the Z axis correspond to an aircraft roll, changes around the X axis correspond to an aircraft pitch.