A new planet-wide electric field that is as fundamental to Earth as gravity has been discovered in a major scientific breakthrough.
The ambipolar electric field, which starts 150 miles above the planet, has been described as a “great invisible force” that lifts the sky and is responsible for the polar winds.
Polar winds interact with the jet stream to help drive the majority of weather patterns around the globe.
Until now, the field has only been established, but a Nasa team, which includes scientists from the University of Leicester, has now sent a rocket to the field and measured it for the first time.
This means that the Earth now has three energy fields: gravity; the magnetic field, which protects the planet from cosmic radiation; and an ambipolar electric field.
Dr Glyn Collinson, principal investigator of the Endurance Mission at NASA Goddard Space Flight Center in Greenbelt, Maryland, said: “Every time a spacecraft has flown over the Earth’s poles, it has experienced supersonic winds of particles called polar winds.
“There must be an invisible force responsible for this outflow, but we have never measured it because we don’t have the technology.
“This field is very important to understanding how planets work. It’s been here since the beginning along with gravity and magnetism. It’s been spreading particles into space and spanning the sky since the beginning.
The field is difficult to detect because it is very weak, only 0.55 volts. But it is enough to almost treble the height of the ionosphere – the part of the upper atmosphere that sits between 30 and 600 miles above sea level. The scale height represents how quickly the atmosphere dissipates, meaning that the ionosphere remains denser at higher altitudes than without.
“Even though it’s weak, it’s very important, fighting gravity and lifting the sky. It’s like a conveyor belt, lifting the atmosphere into space,” added Dr Collinson.
“Half a volt is almost nothing – about as strong as a watch battery. But it’s just the right amount to explain the polar wind.
Understanding the atmosphere is crucial to Earth’s evolution and could help scientists find other habitable planets. The team believes that any planet with an atmosphere is likely to have an ambipolar field.
To get started on the ambipolar electric field, scientists had to travel to the northernmost launch site in the world, at the Ny-Alesund site in Svalbard, Norway, just a few hundred miles from the North Pole.
The mission, which began in 2016, was named Endurance after the ship that carried Ernest Shackleton on his voyage to Antarctica in 1914.
Prof Suzie Imber, a space physicist at the University of Leicester, and co-author of the paper, said: “Svalbard hosts the only rocket in the world that can fly through the polar wind and make the necessary measurements.”
The team found that hydrogen ions, the most abundant type of particle in the polar wind, experience an outward force from this field, which is 10.6 times stronger than gravity.
Alex Glocer, Endurance project scientist at Nasa Goddard and co-author of the paper, said: “This is more than enough to defy gravity – in fact, it’s enough to launch it up into space at supersonic speeds.”
The field’s discovery was announced in the journal Nature.
Dr Collinson added: “What makes Earth such a special place to call home? One of the reasons may have something to do with the energy field our planet creates.
“One is gravity. It is important for life because it holds our atmosphere up. The second field is the magnetic field that protects our planet from the flow of particles coming from the sun
“Our rocket has found, and finally measured, number three. Now that we have finished measuring, we can begin to study how our planet and the rest of the world formed over time.
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