The main part of a hot air balloon is the envelope, which is the large rounded top section. Begin with a simple oval shape or a wide teardrop shape. Keeping your pencil strokes light helps you adjust ...

It makes sense that a balloon filled with a lightweight gas such as helium would float when surrounded by heavier air. But why does filling a huge balloon with hot air also make it float? This ...

James is a published author with multiple pop-history and science books to his name. He specializes in history, space, strange science, and anything out of the ordinary.View full profile James is a ...