Scientists Detect Invisible Electric Field Around Earth
For First Time
SPACE
30 August 2024
ByMICHELLE STARR
Scientists Detect Invisible Electric Field Around Earth
For First Time
Earth as photographed from the International Space
Station in 2003. (NASA)
An invisible, weak energy field wrapped around our
planet Earth has finally been detected and measured.
It's called the ambipolar field, an electric field
first hypothesized more than 60 years ago, and its
discovery will change the way we study and understand
the behavior and evolution of our beautiful, ever-
changing world.
"Any planet with an atmosphere should have an ambipolar
field," says astronomer Glyn Collinson of NASA's
Goddard Space Flight Center.
"Now that we've finally measured it, we can begin
learning how it's shaped our planet as well as others
over time."
Earth isn't just a blob of dirt sitting inert in space.
It's surrounded by all sorts of fields. There's the
gravity field. We don't know a lot about gravity,
especially considering how ubiquitous it is, but
without gravity we wouldn't have a planet. Gravity also
helps keep the atmosphere snug against the surface.
There's also the magnetic field, which is generated by
the rotating, conducting material in Earth's interior,
converting kinetic energy into the magnetic field that
spins out into space. This protects our planet from the
effects of the solar wind and radiation, and also helps
to keep the atmosphere from blowing away.
Earth's North Pole, as seen by Endurance. The streaks
in the sky are from lens flare. (NASA)
In 1968, scientists described a phenomenon that we
couldn't have noticed until the space age. Spacecraft
flying over Earth's poles detected a supersonic wind of
particles escaping from Earth's atmosphere. The best
explanation for this was a third, electric energy
field.
"It's called the ambipolar field and it's an agent of
chaos. It counters gravity, and it strips particles off
into space," Collinson explains in a video.
"But we've never been able to measure this before
because we haven't had the technology. So, we built the
Endurance rocket ship to go looking for this great
invisible force."
Here's how the ambipolar field was expected to work.
Starting at an altitude of around 250 kilometers (155
miles), in a layer of the atmosphere called the
ionosphere, extreme ultraviolet and solar radiation
ionizes atmospheric atoms, breaking off negatively
charged electrons and turning the atom into a
positively charged ion.
The lighter electrons will try to fly off into space,
while the heavier ions will try to sink towards the
ground. But the plasma environment will try to maintain
charge neutrality, which results in the emergence of an
electric field between the electrons and the ions to
tether them together.
This is called the ambipolar field because it works in
both directions, with the ions supplying a downward
pull and the electrons an upward one.
The result is that the atmosphere is puffed up; the
increased altitude allows some ions to escape into
space, which is what we see in the polar wind.
This ambipolar field would be incredibly weak, which is
why Collinson and his team designed instrumentation to
detect it. The Endurance mission, carrying this
experiment, was launched in May 2022, reaching an
altitude of 768.03 kilometers (477.23 miles) before
falling back to Earth with its precious, hard-won data.
And it succeeded. It measured a change in electric
potential of just 0.55 volts – but that was all that
was needed.
"A half a volt is almost nothing – it's only about as
strong as a watch battery," Collinson says. "But that's
just the right amount to explain the polar wind."
That amount of charge is enough to tug on hydrogen ions
with 10.6 times the strength of gravity, launching them
into space at the supersonic speeds measured over
Earth's poles.
Oxygen ions, which are heavier than hydrogen ions, are
also lofted higher, increasing the density of the
ionosphere at high altitudes by 271 percent, compared
to what its density would be without the ambipolar
field.
What's even more exciting is that this is just the
first step. We don't know the broader implications of
the ambipolar field, how long it has been there, what
it does, and how it has helped shape the evolution of
our planet and its atmosphere, and possibly even the
life on its surface.
"This field is a fundamental part of the way Earth
works," Collinson says. "And now we've finally measured
it, we can actually start to ask some of these bigger
and exciting questions."
The research has been published in Nature.
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