A long-sought-after invisible force orbiting the Earth has been discovered more than half a century after it was first hypothesized. The field, called the polar wind, explains how Earth’s atmosphere escapes from the north and south poles so easily and quickly, and may play a role in shaping our planet’s thin upper atmosphere. Scientists say it’s as important to our planet as gravity and magnetic fields.

“This field is so fundamental to understanding how our planet works; it’s been there from the beginning, along with gravity and magnetism,” Glyn Collinson, principal endurance researcher at NASA’s Goddard Space Flight Center in Maryland, said in a video agency. “It’s weak but incredibly important; it defies gravity and almost lifts the sky.”

The hypothesis of the existence of the deposit was first put forward more than 60 years ago. In fact, in the late 1960s, several spacecraft flying over the Earth’s poles detected a stream of particles flying from the atmosphere into space at supersonic speeds. Scientists knew that sunlight causes particles to escape from the atmosphere into space, “like steam evaporating from a pot of water,” but the particles detected by these spacecraft showed no signs of heating.

“Something had to be pulling these particles out of the atmosphere,” Collinson said in a NASA statement. But detecting the existence of a particle-ejecting field that was invisible and so weak (oscillations could only be felt from hundreds of kilometers away) was beyond the technology at the time.

In 2016, Collinson and his colleagues began developing sensors for the launch of the Endurance International Probe Rocket, and in May 2022, one of the suborbital rockets, equipped with eight specialized instruments, launched just a few hundred meters from the Svalbard Mountain Range in Norway—miles from the North Pole. The location provided the rockets with an ideal vantage point to study the unique atmospheric phenomenon.

“Svalbard is the only rocket range in the world where you can fly into the polar wind and make the measurements we need,” study co-author Susie Imber, a space physicist at the University of Leicester in the United Kingdom, said in a statement.

During the 20-minute flight, Endurance reached an altitude of about 477 miles (768 kilometers) and collected data in 322 miles (518 kilometers) of the atmosphere. It cataloged a rapid voltage change of 0.55 volts, “which is almost nothing; it’s about as powerful as a watch battery,” Collinson said. “But it’s exactly what’s needed to explain the polar wind.”

Scientists estimate that the field begins about 150 miles (250 kilometers) above the surface, where atoms in the atmosphere split into negatively charged electrons, which are 1,800 times heavier than electrons, and positively charged ions. Given the opposite electric charges, an electric field is created that “ties them together,” counteracting the constant pull of gravity and allowing some particles to escape into space in the process, NASA explained.

The researchers found that hydrogen ions, abundant in the polar wind, experience an external thrust 10.6 times stronger than gravity. “That’s more than enough to defy gravity — enough, in fact, to launch them into space at supersonic speeds,” study co-author Alex Glosser, Endurance mission scientist at NASA Goddard, said in a statement.

Oxygen ions, which are heavier than their hydrogen counterparts, were also seen getting a speed boost from the polar wind. “It’s like this conveyor belt that lifts the atmosphere into space,” Collison said.

Since the polar wind is excited by internal dynamics SoilScientists expect it to be present on other planets, including Venus and Mars. Studying the phenomenon in more detail could reveal clues about its impact on the evolution of our atmosphere and its impact on our oceans, Collinson said.

“This field is a fundamental part of how the Earth works, and now that we’ve finally measured it, we can start asking some of these bigger and more exciting questions.”

Collinson and colleagues describe their findings in a paper published Wednesday, August 28, in the journal Nature.