🚀 Aviation and space travel

A jet engine sucks in a huge amount of air at the front, then compresses that air tightly before mixing it with fuel and igniting it, creating a powerful blast of hot, expanding gas. That hot gas rushes backward out of the engine at extremely high speed, and by Newton's law that every action has an equal and opposite reaction, this backward blast pushes the entire engine, and the plane attached to it, forward with tremendous force. Modern jet engines are engineered with incredible precision, since their spinning parts inside must handle extreme heat and speed reliably for thousands of flight hours.

Air traffic control is a system of people and radar tracking every single plane flying through a certain area of sky, making sure planes always stay a safe distance apart from each other. Controllers on the ground constantly talk to pilots by radio, giving exact instructions about altitude, speed, and direction, especially during the busiest moments like takeoff and landing near a crowded airport. Because thousands of planes might be flying at once across a country, air traffic control is divided into different zones, with planes handed carefully from one controller to the next as they cross into new areas.

A rocket carries enormous tanks of fuel and oxidiser, a special ingredient that lets fuel burn even without any surrounding air, since there is no air at all once a rocket leaves Earth's atmosphere. Burning that fuel and oxidiser together creates an incredibly powerful blast of hot gas shooting out the bottom of the rocket, and that blast pushes the entire rocket upward with enough force to fight against Earth's gravity pulling it back down. Rockets usually launch in several stages, dropping heavy, empty fuel tanks along the way once they are no longer needed, which makes the rest of the rocket lighter and easier to keep accelerating toward space.

When a spacecraft comes back to Earth, it must slow down from incredibly high speed while smashing through the thick atmosphere, and all that friction against the air creates enormous heat on the outside of the craft. Spacecraft are covered in special heat shields designed to absorb or deflect that intense heat, protecting the astronauts safely inside even as the outside glows fiercely hot. Once the spacecraft has slowed down enough lower in the atmosphere, large parachutes deploy to slow it the rest of the way down gently, allowing for a safe, controlled landing either on land or in the ocean.