Where space begins

Living on a planet means “space” is all around us, a fact most people often overlook or are even still unaware of. Standing on “terra firma”, it is easy to forget that this “firm ground” is actually traveling through space on its own journey around the star we know as “sol”, or the Sun. To journey “into space” generally means traveling throughout the atmosphere to a point where you briefly see the blue sky turn black and into a condition where normal aerodynamic control surfaces such as wings, rudder, and ailerons are useless; only rocket engines can provide the impulse to move under a vacuum condition. It is a con­dition controlled by the forces of gravity pulling on objects in perpetual free fall.

The barrier between blue sky and space has been defined at different altitudes above the Earth. For some it is 50 miles (80.45 km); others state 62 miles (or 100 km), while still others claim you are not in space until you are in orbit and you cannot call yourself a true space explorer unless you have completed at least one orbit of Earth. With even more flights to the edge of the defined atmosphere planned, such as the Virgin Galactic SpaceShipTwo program, so the debate of what is or is not a true flight into space will continue.