This mom is due to the po-po difference in how the two types of beds become airborne (or to use the technical term, achieve "lift"). and they went to the sky. Lighter than air aircraft (known as "aerostats") use buoyancy to float in the air in much the same way that ships float on the water. They typically have one or more large balloons or bags, filled with a relatively low density gas such as helium, hydrogen or hot air, which is less dense than the surrounding air. ♥☺☻