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Today in science from wired.

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Tiny Jetlets

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might be fueling the solar wind. Scientists

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investigated a weird feature in Parker

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Solar Probe data and may have discovered

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what drives the plasma that pervades the solar

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system. By Katrina Miller.

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Streaming out of the sun at a million miles

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an hour, the solar wind, a blistering

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plasma of electrons, protons, and ions

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flowing through space is a decades

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old enigma. Scientists know

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it once stripped Mars of its atmosphere and

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some think it put ice on the moon. Today,

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it causes the glimmering northern lights displays

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and messes with satellite communication systems.

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But researchers haven't been able to nail

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down how the solar wind gets made,

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heats up to millions of degrees, or

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accelerates to fill the entire solar system.

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Now a team of researchers think they've figured

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it out. The solar wind they say

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is driven by Jetlets, tiny intermittent

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loses at the base of the sun's upper atmosphere

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or corona. The theory, which

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has been published in the astrophysical Journal,

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emerged from data taken by NASA's

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Parker Solar Probe, a car sized

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satellite that has repeatedly flown by

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the sun since twenty eighteen. It

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measures properties of the solar wind and

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traces the flow of heat and energy in the

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outermost part of the sun's atmosphere that

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begins about thirteen hundred miles above

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its surface. The team's idea

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is strengthened by data from other satellites

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and ground based telescope showing Jetlets could

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be ubiquitous and powerful enough to account

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for the mass and energy of the solar wind.

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Uncovering its origins will help scientists

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better understand how stars work and

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predict how the gust a flow of plasma affects

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life on Earth. Higher resolution

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data is needed to prove this hypothesis, but

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the evidence so far is tantalizing

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We sensed from early on that we were on to something

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big says Nora Rawafi, an astrophysicist

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at Johns Hopkins University's Applied Physics

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Laboratory who led the study. We

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were thinking that we might be solving the sixty

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year old puzzle of the solar wind and I believe

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we are. The existence

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of solar wind, first proposed by the

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late Eugene Parker, namesake of the

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Parker Solar probe, was confirmed by

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NASA in the early nineteen sixties. Since

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then, scientists have been by how

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that plasma can move as far and

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as fast as it does. The sun's

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corona is hot, millions of degrees

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on any temperature scale, but not

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hot enough to push the solar wind to those

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speeds. Jetlets, on the other hand,

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weren't discovered until twenty fourteen in

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a study led by Rawafi show that these

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many explosions drive coronal plumes,

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bright funnels of magnetized plasma

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near the solar poles. Looking

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closely at the base of the plumes, he

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found that Jetlets arise when the sun's turning

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surface forces two regions of repelling

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magnetic polarity together, until

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they snap. But after that paper,

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rawafi moved on to other projects and we

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basically left it there, he says. Then

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in twenty nineteen, while royalty was working

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as a project scientist on the Parker Solar

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Probe, the craft saw something weird.

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As it skimmed the top of the corona, it observed

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quite often, the direction of the magnetic

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field it was flying through would flip,

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then it would flip back. ROffy

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assembled a team to hunt down a source

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of these intermittent switchbacks lower

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in the atmosphere. His mind immediately

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went to Jetlets. If they could be found

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elsewhere in the corona and not just in

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its plumes, he reasoned they might be

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numerous enough to generate enough material

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and power to be the solar wind itself.

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But the probe can only take samples

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at the very top of the corona, If

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it gets too close, it'll melt. More

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remote satellites are better at seeing deeper

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into the sun, closer to the bottom of the corona.

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So the research team analyzed high resolution

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images of the lower corona from NASA's

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solar dynamics observatory satellite

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and the solar ultraviolet imager instrument

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aboard a super high altitude weather satellite

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that orbits Earth. And sure enough,

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we found what we think is the smoking gun

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for the origin of the solar wind says

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study coauthor Craig DeForest, a

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solar physicist at the Southwest Research

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Institute in Boulder, Colorado. The

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data revealed that Jetlets were everywhere.

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They were also present as far back in

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time as the researchers searched to

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data from two thousand ten. Unlike

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solar flares and coronal mass ejections,

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which wax and wane in a natural eleven

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year cycle, the Jetlets' presence

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didn't vary. Like the solar wind,

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they seem to be a stable feature persistently

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hurling plasma into space. To

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prove the Jetlets go off with enough power

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and are prevalent enough to account for the solar

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wind, the researchers did a rough calculation.

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Up to ten to the thirty fifth protons

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can be ejected per Jetlets. the

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sun loses around six times ten to the thirty

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fifth protons per second to the solar wind.

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That means it would take six jetlets per

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second or about five hundred thousand

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per day to power the wind. They

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compared this number to maps of the sun's surface

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that indicate where Jetlets might be, These

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maps were imaged by the Big Bear Solar

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Observatory in California and show

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variations in the magnetic polarity over

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fine scales. With negative pulls

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and darker patches and positive pulls and lighter

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ones giving the images a salt and pepper

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appearance. The team concluded

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that there were enough sites with neighboring

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opposite poles to potentially produce the

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number of Jetlets needed to fuel the solar wind.

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We haven't sealed case beyond a reasonable

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doubt yet to force says, but

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this is a major step forward. Learning

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about the solar wind is important. The forest

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says, because it's an integral part of our

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own environment, Solar Physics

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is the only field of astrophysics that

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has actual applications on Earth, he says.

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The wind perturbs our planet's magnet magnetic

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field which protects us from potentially harmful

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space radiation. It also causes

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space weather that can affect the orbits and operations

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of satellites, including GPS networks.

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Understanding how solar winds work can

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also help scientists figure out how stars

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slow down as they age and how that

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influences the atmosphere of their orbiting

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planets, which could make them more or less habitable.

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The idea that intermittent explosions could

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generate a steady stream of plasma challenges

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the notion that the solar wind's driving mechanism

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must be a single continuous source. But

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it's not inconceivable. Parker

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did once hypothesized that something like

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this could fuel the wind, though he called

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them nano flares. And DeForest

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points out that many small bursts can collectively

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act like one smooth flow. You

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drive a car down the road and what you feel

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is a smooth thrust, he says. But really,

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what's going on is zillions of little explosions

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inside the gas engine. Charles

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Kinklberg, a solar physicist at Montana

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State University, finds the theory plausible,

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but the idea itself surprises him.

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Tiny explosions like those created by

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other kinds of small solar events have never

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been shown to meaningfully contribute to the

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energy of the Sun's atmosphere. To

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see this paper suggesting that these could

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very well be supplying the full solar wind

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as we know it. My jaw kind of

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dropped says Kinklebork, who was not involved

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in the work. It'll take more data for

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him to leave that Jetlets alone can supply

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the wind's energy, but he feels it's an exciting

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idea worth considering. Rowafi

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and his colleagues are on it. Higher resolution

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data already shows that they've underestimated the

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speed of Jetlets, meaning they have more

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energy than originally accounted for. Which

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is a very good sign. That's what

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we need, he says. Two follow-up

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studies are in the works and ROACE hopes

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to publish them this summer. Those will

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include more observations from the solar dynamics

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observatory, new data by the European

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Space Agency's solar orbiter, and magnetic

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field from Daniel Kaye in a way

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solar telescope in Hawaii, which

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has three times the magnetic field resolution

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of Big Bear solar Observatory. In

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the future, linking this data with direct measurements

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by the Parker Solar Probe as well

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as more global observations of the solar wind

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from NASA's coming polarimeter to unify

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the corona and heliosphere or punch

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mission will help scientists glean

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even more precise information about

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its nature. Bringing these two

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tools together, remote imaging and

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at the source measurements means we'll

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really get a handle on the system as unified

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whole says to forest. Who is the principal

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investigator for the punch mission. The

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team is confident that they're on the brink

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of a big discovery. I wish Gene Parker

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was still with us. Rawafi says, I

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believe that he would have been pleased that we

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are in a way confirming his theory.

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