In a paper published this week in Nature, Google researchers demonstrated they were able to use GPS signal measurements pulled from millions of anonymous Android mobile devices to map the ionosphere.

When the air is partly ionized, freely moving electrons slightly slow down the radio signals travelling to Earth from GPS and other navigation satellites. This can affect the nanosecond-precision timing that satellite navigation devices use to pinpoint their locations, with potentially serious impacts on aeroplane landings and autonomous vehicles.

Researchers mapped Earth’s ionosphere, part of the upper atmosphere, using signal data from 40 million phones – a method that could improve GPS accuracy and help track space weather