Scientists Detect Invisible Electric Field Around Earth For First Time 21
Scientists have finally detected and measured the ambipolar field, a weak electric field surrounding Earth that was first theorized over 60 years ago. "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." ScienceAlert reports: 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. The findings have been published in the journal Nature.
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. The findings have been published in the journal Nature.
It would be more surprising ... (Score:5, Funny)
... if they detected a _visible_ electric field
Re: It would be more surprising ... (Score:2)
https://m.youtube.com/watch?v=... [youtube.com]
Re: (Score:2)
https://m.youtube.com/watch?v=... [youtube.com]
Bill Nelson is a nice surprise.
Re: (Score:2)
So what does it look like?
"invisible electric field" (Score:2)
As opposed to a visible electric field??
Re: (Score:3)
It's an emphasis of their astounding achievement. They found something that you can't see, but it's really there anyway! It's science, but almost magic! You CAN'T SEE IT!
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re:As opposed to visible electric field? (Score:1)
It's what keeps sharks away from batteries. Donnie says so, and he's the most stable genius in the history of the world, everyone know it!
-5 Political Troll
watch battery? (Score:4, Interesting)
Most watch batteries are 1.5v or 3v nominal. But whatever, what's interesting about this is that half a volt is really quite a bit. Given the size of the atmosphere, that must be quite a lot of potential in total.
Re:watch battery? (Score:4, Informative)
Most watch batteries are 1.5v or 3v nominal. But whatever, what's interesting about this is that half a volt is really quite a bit. Given the size of the atmosphere, that must be quite a lot of potential in total.
It’s exceptionally hard to measure because the actual potential difference between the surface and upper atmosphere is around half a million volts. This half volt is just a wisp of net charge on atmosphere and surface together.
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The actual science ... (Score:5, Informative)
There's a hint in the abstract :
"Here we report the existence of a +0.55â+/-â0.09âV electric potential drop between 250âkm and 768âkm from a planetary electrostatic field"
Which sounds to me as if they dropped the spacecraft faring at (say) 200km, then measured [something] until their sounding rocket reached the crest of it's flight. Then (I infer) started closing down the instruments before reentry. Which I'll return to.
According to Unpaywall, there is no un-paywalled version of the article legally available (is SciHub still working, somewhere?). But the lead author, "Glyn A Collinson" has a publication history which includes "A hybrid electrostatic retarding potential analyzer for the measurement of plasmas at extremely high energy resolution" (Rev. Sci. Instrum. 89, 113306 (2018), https://pubs.aip.org/aip/rsi/a... [aip.org]) which is freely available (https://ntrs.nasa.gov/api/citations/20190002417/downloads/20190002417.pdf). From that paper,
"One type of plasma which greatly benefits from high resolution spectroscopy is the âoephotoelectronsâ given off by planetary atmospheres"
- which sounds like the sort of instrumentation that would do the job required.
That may not be the instrument used - bloody paywalls ! - but it sounds like that is what the lead author has been developing for a while, so it's unlikely to be unrelated.
I'm a geologist, not a physicist, but I need to have some sort of understanding of the tool physics of my instruments to understand what they're telling me. That paper contains enough to give me hints into how they measure the energy spectrum of free electrons as flight progresses, and their changing abundance would trace the electrostatic field. The schematics in Fig 1 are enlightening. It's an intriguing combination of one instrument to select part of the plasma (electrons, in this case), then a second instrument to report on their energy distribution. Interesting. Canny thinking.
Oh well, back to the peanut gallery to make jokes about visible vs invisible fields. [SIGH] I'd like to say that Slashdot was never like this in the "good old days", but I was here then, and it wasn't much different. Oook! Oook! Peanuts!
air has 100V per meter above the ground (Score:5, Interesting)
It's recently been established that the ballooning of spiders does not require a breeze, it can be driven by static electricity, and the air carries a voltage of around 100 volts for every meter above the ground. That's not a typo. 100 volts per meter.
https://www.theatlantic.com/sc... [theatlantic.com]
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To put it into context, the breakdown electrical potential of dry, sea-level (-ish) air is closer to 100 Volts per mm. Order of 1000 times greater.
Or, a different perspective : This afternoon I was taking a walk with Dad (he looking for a locally rate plant, a tiny ground hugging thing in the genus Plantago ; me encouraging Dad to exercise his braincells) and we passed under a HV power line at (probably) 440kv AC, some 15m above u
Basic physics (Score:2)
Audible electric field (Score:3)
Long ago on a family trip to Maryland, when I was at high school age, we were near Annapolis, somewhere in an accessible area of a Navy installation. The VLF antenna farm was visible from the site. There was a static display of a submarine conning tower, likely from previous use as a training fixture.
I climbed up and was enjoying the view, when I heard an erratic ticking sound. Eventually I located the source. At the base of an antenna mast was a stub of coaxial cable from which the connector had been removed. This was a short distance above a metal deck plate that would have been near ground potential. A spark was jumping between the coaxial conductor and the deck plate.
Noting the darkening sky and recalling the popularity of lightning rods on barns in rural Pennsylvania, and my own experiments with automobile ignition coils, I skeedaddled off the fixture.
Giant Space Cat ... (Score:2)
What I'd love to know ... (Score:1)
I don't know, and for no reason I am interested in defending here, I feel that a lot more atmosphere may have existed prior to the Flood and been topped by a water vapour canopy. When the canopy went, the extra atmosphere simply drifted away. But I'd lov
So we knew this back in the 1970's in school (Score:2)