Saturday, August 2, 2014

Where does earth end and space begin?

Finding the border between the two is not as simple or scientific as you might think 

Flight Engineer Chris Cassidy replaces a pump controller box, leaking ammonia coolant on the International Space Station, May 11, 2013. Photo courtesy NASA 

Flight Engineer Chris Cassidy replaces a pump controller box, leaking ammonia coolant on the International Space Station, May 11, 2013. Photo courtesy NASA.

Any time we embark upon a journey, be it a morning commute or a leisurely day trip, we engage in transition. We are a travelling species, which means transitions are commonplace for us, mundane even. But there are some trips that can still fire the human imagination, and none more so than the journey, experienced only by a lucky few, from the surface of Earth to the beginning of space.

On his 108-minute flight in 1961, the Soviet cosmonaut Yuri Gagarin, the first human being in space, reached a peak altitude of 327 kilometres (203 miles), after blasting off the planet atop a mighty Vostok rocket. After launch shook his tiny capsule violently, Gagarin experienced the feeling of weightlessness, and saw the curvature of the Earth first-hand. By all accounts, he crossed the mysterious border between the Earth and space. Or did he? It has been more than half a century since Gagarin’s historic journey, but there is still no universally accepted definition of where space begins.

There is general agreement that ‘space’ starts where the Earth’s physical influence ends or is significantly displaced, but no consensus as to where that line actually lies. Does space begin where the Earth’s atmosphere ends? That would seem sensible, except the atmosphere extends some 800 kilometres above the planet. That would exclude Gagarin’s flight, and the International Space Station (ISS) whose orbit around the Earth is only 400 kilometres high. Earth’s gravity might well seem like another natural candidate for ‘edge of space’ status, but you have to travel 21 million kilometres before our planet's gravity loses out to other forces, and that's roughly halfway to Venus.

For the rest of the story: http://aeon.co/magazine/altered-states/where-is-the-border-between-earth-and-space/

No comments:

Post a Comment

Related Posts Plugin for WordPress, Blogger...