23 Mayo 2017 12:11
The Earth, and everybody on it, is protected by a bubble of radiation that we created by accident. Scientists first learned of the bubble when two NASA probes, orbiting Earth, spotted a shield around the planet that hadn't been there before. It was as if the world had been wrapped in bubble wrap.
The bubble has been formed thanks to highly unusual interplay between technology and nature in which radio communications from the ground interact with high-energy radiation particles in space, forming a protective barrier around Earth. This barrier shields the planet from potentially dangerous space weather like solar flares and other ejections from the sun.
In 2012, a robotic mission sent to investigate the Van Allen radiation belts – two doughnut-shaped rings of charged particles that surround the Earth – first revealed the bubble.
The blue rings represent the Van Allen belt
Five years on, the data collected by the mission has now been thoroughly analysed and the results are described in a study in Space Science Reviews. According to The Atlantic, some low frequency waves, or VLFs – used, for example, when communicating with submarines beneath the ocean surface – rise to a point beyond the Earth's atmosphere, where they affect the movement of radiation particles bouncing around in the region.
The interaction between VLFs and these particles has created this protective bubble. Scientists say the edge of the outer edge of artificial bubble lines up almost exactly with the inner edge of the Van Allen belts, which suggests VLF waves can push radiation particles away.
Comparing current satellite images with those of the 1960s, when there were far fewer VLF transmissions being sent, reveals that the inner edge of the belts is much further from Earth now than it was then.
Humans have serendipitously blundered into creating an extra layer of defence against the hostile universe. There may be hope for us yet.