Star-planet system geometry when tidal interactions occur. The spherical shapes that star and the planet would have in the absence of tidal interactions are drawn in red and dark brown. The tidal bulges are drawn in orange and light brown, respectively. They arise on the stellar and planetary surfaces (respectively in orange and light brown) and rotate with the star itself and are elongated in the direction of the other body. The tidal lags are also drawn. The image is not to scale.