A significant part of aeronautical science is a branch of dynamics called aerodynamics, which deals with the motion of air and the way that it interacts with objects in motion, such as an aircraft.
When you pour a liquid from one container to another, the liquid takes the shape of the container. The volume of the liquid is the same. The properties that solids and liquids share are that they both have definite volume.
Liquids are similar to solids in that the particles touch. However the particles are able to move around. Since particles are able to touch, the densities of liquid will be close to that of a solid. Since the liquid molecules can move, they will take the shape of their container.