Flight

Have you ever wondered how a bird flies, or how a heavy airplane stays in the sky? Flight occurs when an object moves through the atmosphere instead of falling towards the Earth. This object can be an aircraft, a spaceship, a rocket, a balloon, a bird, or an insect. In order for something to fly, it has to be lighter than the air around it or powerful enough to defy gravity, which is the Earth’s pull. When a plane gains a lot of speed, its wings push air underneath and the plane rises. When a bird flaps its wings, it creates lift by pushing air underneath. When a balloon rises, the air or gas in it is lighter than the air outside it. And when a rocket soars through the sky, its powerful engines generate enough thrust to defy gravity.

Humans have dreamt of flying for centuries, yet have never flown without using technology. Our hearts cannot pump fast enough to flap the giant wings we would need to fly. For a sparrow to fly its heart needs to pump more than 450 times per minute. The technological equivalents of this are the powerful engines passenger airplanes need to fly. These engines are strong enough to blow nearby cars through the air! But a long time before planes the first man-made flight was an ancient Chinese kite.