How Solar Prominences Vibrate

An international team led by researchers from the Instituto de Astrofísica de Canarias (IAC) and the Universidad de La Laguna (ULL) has cataloged around 200 oscillations of the solar prominences during the first half of 2014. Its development has been possible thanks to the GONG network of telescopes, of which one of them is located in the Teide Observatory.

When we look at the surface of the Sun the solar prominences are seen as dark filaments that populate the disk or as a blaze of plasma above it. Solar prominences are very dense plasma structures that levitate in the solar atmosphere. It is generally believed that the star’s magnetic field supports them so that they do not fall on the surface due to their own weight. These magnetic structures can accumulate a large amount of energy that, when released, produces eruptions ejecting the prominence material into the interplanetary space.

Manuel Luna, researcher at the IAC and the ULL, leads the team that has cataloged about 200 solar prominence oscillations detected in the first half of 2014. This analysis, published today in the Astrophysical Journal Supplement series, has served to verify that almost half of these events have been of large-amplitude. That is, oscillations with speeds between 10 km/s (36000 km/h) and 100 km/s. It has also been proven that these large-amplitude events are more common than previously thought.

The project is part of an international collaboration that began in 2015 through the International Space Science Institute (ISSI) and also the NASA project for the study of this type of oscillations.

Thanks to this compilation, a large variety of events have been found and it has been determined that, in many cases, the oscillations are produced by nearby flares. That is, by the sudden release of energy in the solar atmosphere.

With the collected data, a statistical study of the properties of the oscillations has been carried out. These movements consist of a cyclic movement of the prominences between two positions. It has been seen in it, that the oscillations (vibrations) have a period of approximately one hour. These periods are a characteristic of the prominences and reveal fundamental properties of their magnetic structure and the distribution of their mass. In addition, the oscillations show a large damping, or what is the same the vibration is reduced considerably after few cycles of oscillation. It is unknown why most of the protuberances oscillate with a period of one hour or why their movement is damped so quickly, therefore it will be necessary to continue investigating.

The data suggest that “the direction of movement of the oscillations forms an angle of about 27 degrees with the main axis of the prominence,” Luna explains. He adds: “This direction coincides with the previous estimates of the orientation of the magnetic field.” In addition, using seismological techniques, researchers have been able to deduce details about the geometry and intensity of the magnetic field that supports the prominences.

This study opens a new window to the investigation of the structure of the solar prominences and to the mechanisms that eventually destabilize them producing their eruption. In the future, the authors want to extend this analysis to an entire solar cycle to understand the evolution of these structures over the 11 years it lasts. To achieve this, artificial intelligence and big-data processing techniques will have to be applied.

As Solar Wind Blows, Our Heliosphere Balloons

What happens when the solar wind suddenly starts to blow significantly harder? According to two recent studies, the boundaries of our entire solar system balloon outward—and an analysis of particles rebounding off of its edges will reveal its new shape.

In late 2014, NASA spacecraft detected a substantial change in the solar wind. For the first time in nearly a decade, the solar wind pressure—a combined measure of its speed and density—had increased by approximately 50 percent and remained that way for several years thereafter. Two years later, the Interstellar Boundary Explorer, or IBEX, spacecraft detected the first sign of the aftermath. Solar wind particles from the 2014 pressure increase had reached the edge of the heliosphere, neutralized themselves, and shot all the way back to Earth. And they had a story to tell.

In two recent articles, scientists used IBEX data along with sophisticated numerical models to understand what these rebounding atoms can tell us about the evolving shape and structure of our heliosphere, the giant bubble carved out by the solar wind.

“The results show that the 2014 solar wind pressure increase has already propagated from the Sun to the outer heliosphere, morphing and expanding our heliosphere’s boundaries in their closest direction,” said David McComas, the principal investigator for the IBEX mission at Princeton University in Princeton, New Jersey. “IBEX data pouring in over the next few years will let us chart the expansion and evolving structure of the other portions of the heliosphere’s outer boundaries.”

From the Sun to the edge of the solar system—and backAt the crux of the story are energetic neutral atoms—high-energy particles produced at the very edge of our solar system.

As the solar wind flows out from the Sun at supersonic speeds, it blows up a bubble known as the heliosphere. The heliosphere encases all the planets in our solar system and much of the space beyond them, separating the domain of our Sun from that of interstellar space.

But the solar wind’s journey from the Sun is not a smooth ride. On its way to the very edge of our heliosphere, known as the heliopause, the solar wind passes through distinct layers. The first of these is known as the termination shock.

Before passing the termination shock, the solar wind expands rapidly, largely unimpeded by outside material.

“But at the termination shock, roughly 9.3 billion miles away from us in every direction, the solar wind slows down abruptly. Beyond this point it continues to move outwards, but it is much hotter,” said Eric Zirnstein, lead author of one of the papers at Princeton.

Once beyond the termination shock, solar wind particles enter a special limbo zone known as the heliosheath. While the termination shock is essentially spherical, the edges of the heliosphere are thought to describe more of an arc around the Sun as it moves through space—closer to the Sun toward the front, and extending long behind it, not unlike a comet with a tail. Along these boundaries, solar wind particles mix with particles from interstellar space. Collisions are inevitable: the hot, electrically-charged solar wind particles bang into the slower, colder neutral atoms from interstellar space, stealing an electron and becoming neutral themselves.

“From there they go travelling ballistically through space, and some make it all the way back to Earth,” Zirnstein said. “These are the energetic neutral atoms that IBEX observes.”

In late 2016, when IBEX’s energetic neutral atom imager began to pick up an unusually strong signal, Professor McComas and his team set out to investigate its cause. Their findings are reported in an article published on March 20, 2018, in the Astrophysical Journal Letters.

The energetic neutral atoms were coming from about 30 degrees south of the interstellar upwind direction, where the heliosheath was known to be closest to Earth.

To quantify its connection to the 2014 solar wind pressure increase, McComas and his team turned to numerical simulations, working out how such a pressure increase could affect the energetic neutral atoms that IBEX observes.

“These types of simulations involve a model for the physics, which then gets turned into equations, which are in turn solved on a supercomputer,” said Jacob Heerikhuisen, a coauthor on both papers at the University of Alabama in Huntsville.

Using computer models, the team simulated an entire heliosphere, jolted it with a solar wind pressure increase, and let it run the numbers. The simulation completed a story only hinted at by the data.

According to the simulation, once the solar wind hits the termination shock it creates a pressure wave. That pressure wave continues on to the edge of the heliosphere and partially rebounds backwards, forcing particles to collide within the (now much denser) heliosheath environment that it just passed through. That’s where the energetic neutral atoms that IBEX observed were born.

The simulations provided a compelling case: IBEX was indeed observing the results of the 2014 solar wind pressure increase, more than two years later.

But the simulation didn’t stop there. It also revealed that the 2014 solar wind pressure increase would, over time, continue to blow up the heliosphere even further. Three years after the solar wind pressure increase—by the time the article was published—the termination shock, the inner bubble within the heliosphere, should expand by seven astronomical units, or seven times the distance from Earth to the Sun. The heliopause, the outer bubble, should expand by two astronomical units, with an additional two the following year.

In short, by cranking up the pressure of the solar wind, our heliosphere today is bigger than it was just a few years ago.

The heliosphere’s new shape

McComas and colleagues studied the very first signs of the 2014 solar wind pressure increase. But watching the data over the coming years may tell us even more—this time about the evolving shape of our heliosphere.

“There have been many studies, some from quite a while ago, predicting what the heliosphere shape should look like,” Zirnstein, the lead author of the paper, reports. “But it’s still very much up for debate in the modelling community. We’re hoping that the 2014 solar wind pressure increase could help with that.”

Using the same data and simulations used in the previous paper, Zirnstein and colleagues ran the clock forward, modeling the heliosphere eight years after the 2014 solar wind pressure increase. The results describe not only the past, but also model the future. The paper was published on May 30, 2018, in The Astrophysical Journal.

“What we think we should see in the near future is a ring, expanding across the sky, marking the change in energetic neutral atom flux over time,” said Zirnstein. “This ring expands away from the point of initial contact in the outer heliosphere, towards the directions of the heliotail.”

Although the initial signal detected by IBEX in 2016 was a solid circle, it won’t stay that way. As the 2014 solar wind reaches points of the heliopause further and further away, they take longer to bounce back, like an echo off of a far-away wall. The heliosphere’s rounded shape causes this echo to reflect back in the form of a ring.

But the key finding came from watching the ring as it expands.

In their simulation, Zirnstein and colleagues found that the precise rate at which the ring expands depended in part on the distances between the various layers of the heliosphere: the termination shock, the heliopause, and the part of the heliosheath where the energetic neutrals were produced. Zirnstein realized he had found a new way to measure the size and shape of the heliosphere.

“We could estimate the distances to the different boundaries of the heliosphere just by looking at this ring changing over time in the sky,” said Zirnstein.

Zirnstein and colleagues used their simulated heliosphere to run a test study. By measuring the rate of expansion of the ring (and plugging it into the right equations), they could accurately reproduce the distances to key structures within their simulated heliosphere. Since they knew what those distances were in their simulation, they could check their work—validating that the technique got the right answers and should be accurate when applied to the real heliosphere.

Deformities in the ring—deviations from a perfect circle—could also reveal asymmetries in the heliosphere’s overall shape. “It depends on how symmetric or asymmetric the heliosphere is,” Zirnstein added. “If the heliosphere was an ideal ‘comet shape,’ the ring should expand symmetrically over time. But in reality that’s probably not going to happen—we’ll have to wait and see what IBEX tell us.”

Zirnstein expressed excitement about the possibility of learning the true shape of the heliosphere.

“Over the next few years with more IBEX data, my hope is that we can build a 3-D picture of the shape of the heliosphere,” said Zirnstein.

The results of these two studies have important practical implications. “Connecting changes in the Sun with energetic neutral atom observations will help us understand long term changes in the hazardous conditions for space radiation environment—a sort of space climate as opposed to space weather,” McComas said. “As the solar wind blows more and less hard, and our solar bubble expands and contracts, which directly affects the amount of cosmic rays that can enter the heliosphere, potentially endangering astronauts on long duration spaceflights.”

But the results also underscore the incredible power of our closest star. Changes on the Sun, including the solar wind, have significant consequences extending billions of miles into space where, to date, only the two Voyager spacecraft have ever ventured. With techniques like energetic neutral atom imaging, we cannot just picture, but precisely measure these far-off portions of the heliosphere—our home in the galaxy.

EOVSA Reveals New Insights Into Solar Flares’ Explosive Energy Releases

Last September, a massive new region of magnetic field erupted on the Sun’s surface next to an existing sunspot. The powerful collision of magnetic fields produced a series of potent solar flares, causing turbulent space weather conditions at Earth. These were the first flares to be captured, in their moment-by-moment progression, by New Jersey Institute of Technology’s (NJIT) recently expanded Owens Valley Solar Array (EOVSA).

With 13 antennas now working together, EOVSA was able to make images of the flare in multiple radio frequencies simultaneously for the first time. This enhanced ability to peer into the mechanics of flares offers scientists new pathways to investigate the most powerful eruptions in our solar system.

“These September flares included two of the strongest of the current 11-year solar activity cycle, hurling radiation and charged particles toward Earth that disrupted radio communications,” said Dale Gary, distinguished professor of physics at NJIT’s Center for Solar-Terrestrial Research (CSTR) and EOVSA’s director. The last flare of the period, on September 10, was “the most exciting,” he added.

“The sunspot region was just passing over the solar limb — the edge of the Sun as it rotates — and we could see the comparative height of the flare in many different wavelengths, from optical, to ultraviolet, to X-rays, to radio,” he recounted. “This view provided a wonderful chance to capture the structure of a large solar flare with all of its ingredients.”

Radio emissions are generated by energetic electrons accelerated in the corona, the Sun’s hot upper atmosphere. Modern solar physics relies on observations at many wavelengths; radio imaging complements these by directly observing the particle acceleration that drives the whole process. By measuring the radio spectrum at different places in the solar atmosphere, especially when it is able to do so fast enough to follow changes during solar flares, it becomes a powerful diagnostic of the fast-changing solar environment during these eruptions.

EOVSA, which is funded by the National Science Foundation, is the first radio imaging instrument that can make spectral images fast enough — in one second — to follow the rapid changes that occur in solar flares. This capability allows the radio spectrum to be measured dynamically throughout the flaring region, to pinpoint the location of particle acceleration and map where those particles travel. Images of solar flares at most other wavelengths show only the consequences of heating by the accelerated particles, whereas radio emission can directly show the particles themselves.

“One of the great mysteries of solar research is to understand how the Sun produces extremely high-energy particles in such a short time,” Gary noted. “But to answer that question, we must have quantitative diagnostics of both the particles and the environment, especially the magnetic field that is at the heart of the energy release. EOVSA makes that possible at radio wavelengths for the first time.”

Gary presented EOVSA’s new findings this week at the Triennial Earth-Sun Summit (TESS) meeting, which brings together the solar physics division of the American Astronomical Society (AAS) and the solar physics and aeronomy section of the American Geophysical Union (AGU).

“EOVSA’s new results have sparked lots of interest at the TESS meeting,” said Bin Chen, assistant professor of physics at CSTR, who is chairing a session focused on the intense solar activity that occurred last September. “A number of experts at the meeting commented that these results would add fundamentally new insights into the understanding of energy release and particle acceleration in solar flares.”

Among other discoveries, scientists at EOVSA have learned that radio emissions in a flare are spread over a much larger region than previously known, indicating that high-energy particles are promptly transported in large numbers throughout the explosive magnetic field “bubble” called a coronal mass ejection (CME).

“This is important because CMEs drive shock waves that further accelerate particles that are dangerous to spacecraft, astronauts and even people in airplanes flying polar routes. To date, it remains a mystery how these shock waves alone accelerate particles, because the physics is not understood,” he said. “One of the theories is that ‘seed’ particles must be present in the shock region, which can generate the waves necessary for further acceleration. It has long been speculated that flares, which are known to accelerate particles, may provide them. Previous observations, mainly with X-rays, always show those particles confined to very low heights and it has not been understood how such particles could get to the shock. The radio images show evidence for particles in a much larger region, giving them more opportunity to gain access to the shock region.”

Sunspots are the primary generator of solar flares, the sudden, powerful blasts of electromagnetic radiation and charged particles that burst into space during explosions on the Sun’s surface. Their turning motion causes energy to build up that is released in the form of flares.

EOVSA was designed to make high-resolution radio images of flares (1-second cadence), sunspot regions (20-minute cadence), the full Sun (a few per day) and hundreds of frequencies over a broad frequency band, making it the first solar instrument able to measure the radio spectrum from point-to-point in the flaring region.

“We are working towards a calibration and imaging pipeline to automatically generate microwave images observed by EOVSA, and make them available to the community on a day-to-day basis,” added Chen, who is leading the EOVSA pipeline effort.

“The most unexpected revelation so far from EOVSA is what we see at the lowest radio frequencies,” Gary noted. “Observations of flares based on high radio frequencies and based on X-ray observations show a flare that is a relatively small, compact region even though we see evidence for heating over a much larger area. Although we had rare observations from the past that seemed to show large radio sources, EOVSA has now made it routine to image large radio sources that are even bigger at lower frequencies.”

Initially, he and his colleagues were unable to tap into these new regions, however. After the array was completed, they realized that cell phone towers in the Owens Valley were causing much higher levels of radio frequency interference than expected. As a result, they designed “notch” filters that were able to cut out the frequencies most affected by cell towers.

“This is important because a lot of interesting solar radio bursts occur in the cell tower range (1.9-2.2 GHz). It is the lower frequencies that best show this new and not well understood phenomenon of large sources,” Gary said. “Somehow, the accelerated particles are being transported to a much greater volume of the corona than we thought.”

With new funding from NASA, Gary and colleagues will measure the spatially-resolved radio spectrum of solar flares, determine the particle and plasma parameters as a function of position and time, and then use 3-dimensional modeling, which his group has developed, to fully understand the initial acceleration and subsequent transport of high-energy particles.

The Sun goes through 11-year cycles of activity, and this past year may have provided the last flares we will see for the next four or five years,” Gary said. “For the next few years, we will focus our efforts on improving the active sunspot regions and full-disk images with the array. This imaging on a larger spatial scale is more challenging, but could be just as important, since the larger scale features govern the Sun’s influence on the Earth’s atmosphere and the solar wind.”

New Views Of Sun: Two Missions Will Go Closer To Our Star Than Ever Before

As we develop more and more powerful tools to peer beyond our solar system, we learn more about the seemingly endless sea of faraway stars and their curious casts of orbiting planets. But there’s only one star we can travel to directly and observe up close—and that’s our own: the Sun.

Two upcoming missions will soon take us closer to the Sun than we’ve ever been before, providing our best chance yet at uncovering the complexities of solar activity in our own solar system and shedding light on the very nature of space and stars throughout the universe.

Together, NASA’s Parker Solar Probe and ESA’s (the European Space Agency) Solar Orbiter may resolve decades-old questions about the inner workings of our nearest star. Their comprehensive, up-close study of the Sun has important implications for how we live and explore: Energy from the Sun powers life on Earth, but it also triggers space weather events that can pose hazard to technology we increasingly depend upon. Such space weather can disrupt radio communications, affect satellites and human spaceflight, and—at its worst—interfere with power grids. A better understanding of the fundamental processes at the Sun driving these events could improve predictions of when they’ll occur and how their effects may be felt on Earth.

“Our goal is to understand how the Sun works and how it affects the space environment to the point of predictability,” said Chris St. Cyr, Solar Orbiter project scientist at NASA’s Goddard Space Flight Center in Greenbelt, Maryland. “This is really a curiosity-driven science.”

Parker Solar Probe is slated to launch in the summer of 2018, and Solar Orbiter is scheduled to follow in 2020. These missions were developed independently, but their coordinated science objectives are no coincidence: Parker Solar Probe and Solar Orbiter are natural teammates.

Studying the solar corona

Both missions will take a closer look at the Sun’s dynamic outer atmosphere, called the corona. From Earth, the corona is visible only during total solar eclipses, when the Moon blocks the Sun’s most intense light and reveals the outer atmosphere’s wispy, pearly-white structure. But the corona isn’t as delicate as it looks during a total solar eclipse—much of the corona’s behavior is unpredictable and not well understood.

The corona’s charged gases are driven by a set of laws of physics that are rarely involved with our normal experience on Earth. Teasing out the details of what causes the charged particles and magnetic fields to dance and twist as they do can help us understand two outstanding mysteries: what makes the corona so much hotter than the solar surface, and what drives the constant outpouring of solar material, the solar wind, to such high speeds.

We can see that corona from afar, and even measure what the solar wind looks like as it passes by Earth—but that’s like measuring a calm river miles downstream from a waterfall and trying to understand the current’s source. Only recently have we had the technology capable of withstanding the heat and radiation near the Sun, so for the first time, we’re going close to the source.

“Parker Solar Probe and Solar Orbiter employ different sorts of technology, but—as missions—they’ll be complementary,” said Eric Christian, a research scientist on the Parker Solar Probe mission at NASA Goddard. “They’ll be taking pictures of the Sun’s corona at the same time, and they’ll be seeing some of the same structures—what’s happening at the poles of the Sun and what those same structures look like at the equator.”

Parker Solar Probe will traverse entirely new territory as it gets closer to the Sun than any spacecraft has come before—as close as 3.8 million miles from the solar surface. If Earth were scaled down to sit at one end of a football field, and the Sun at the other, the mission would make it to the four-yard line. The current record holder, Helios B, a solar mission of the late 1970s, made it only to the 29-yard line.

From that vantage point, Parker Solar Probe’s four suites of scientific instruments are designed to image the solar wind and study magnetic fields, plasma and energetic particles—clarifying the true anatomy of the Sun’s outer atmosphere. This information will shed light on the so-called coronal heating problem. This refers to the counterintuitive reality that, while temperatures in the corona can spike upwards of a few million degrees Fahrenheit, the underlying solar surface, the photosphere, hovers around just 10,000 degrees. To fully appreciate the oddity of this temperature difference, imagine walking away from a campfire and feeling the air around you get much, much hotter.

Solar Orbiter will come within 26 million miles of the Sun—that would put it within the 27-yard line on that metaphorical football field. It will be in a highly tilted orbit that can provide our first-ever direct images of the Sun’s poles—parts of the Sun that we don’t yet understand well, and which may hold the key to understanding what drives our star’s constant activity and eruptions.

Both Parker Solar Probe and Solar Orbiter will study the Sun’s most pervasive influence on the solar system: the solar wind. The Sun constantly exhales a stream of magnetized gas that fills the inner solar system, called solar wind. This solar wind interacts with magnetic fields, atmospheres, or even surfaces of worlds throughout the solar system. On Earth, this interaction can spark auroras and sometimes disrupt communications systems and power grids.

Data from previous missions have led scientists to believe the corona contributes to the processes that accelerate particles, driving the solar wind’s incredible speeds—which triple as it leaves the Sun and passes through the corona. Right now, the solar wind travels some 92 million miles by the time it reaches the spacecraft that measure it—plenty of time for this stream of charged gases to intermix with other particles traveling through space and lose some of its defining features. Parker Solar Probe will catch the solar wind just as it forms and leaves the corona, sending back to Earth some of the most pristine measurements of solar wind ever recorded. Solar Orbiter’s perspective, which will provide a good look at the Sun’s poles, will complement Parker Solar Probe’s study of the solar wind, because it allows scientists to see how the structure and behavior of the solar wind varies at different latitudes.

Solar Orbiter will also make use of its unique orbit to better understand the Sun’s magnetic fields; some of the Sun’s most interesting magnetic activity is concentrated at the poles. But because Earth orbits on a plane more or less in line with the solar equator, we don’t typically get a good view of the poles from afar. It’s a bit like trying to see the summit of Mount Everest from the base of the mountain.

That view of the poles will also go a long way toward understanding the overall nature of the Sun’s magnetic field, which is lively and extensive, stretching far beyond the orbit of Neptune. The Sun’s magnetic field is so far-reaching largely because of the solar wind: As the solar wind streams outward, it carries the Sun’s magnetic field with it, creating a vast bubble, called the heliosphere. Within the heliosphere, the solar wind determines the very nature of planetary atmospheres. The heliosphere’s boundaries are shaped by how the Sun interacts with interstellar space. Since Voyager 1’s passage through the heliopause in 2012, we know these boundaries dramatically protect the inner solar system from incoming galactic radiation.

It’s not yet clear how exactly the Sun’s magnetic field is generated or structured deep inside the Sun—though we do know intense magnetic fields around the poles drives variability on the Sun, causing solar flares and coronal mass ejections. Solar Orbiter will hover over roughly the same region of the solar atmosphere for several days at a time while scientists watch tension build up and release around the poles. Those observations may lead to better awareness of the physical processes that ultimately generate the Sun’s magnetic field.

Together, Parker Solar Probe and Solar Orbiter will refine our knowledge of the Sun and heliosphere. Along the way, it’s likely these missions will pose even more questions than they answer—a problem scientists are very much looking forward to.

“There are questions that have been bugging us for a long time,” said Adam Szabo, mission scientist for Parker Solar Probe at NASA Goddard. “We are trying to decipher what happens near the Sun, and the obvious solution is to just go there. We cannot wait—not just me, but the whole community.”

BREAKING NEWS: Two Missions Will Go Closer to Our Sun Than Ever Before

Two upcoming missions will soon take us closer to the Sun than we’ve ever been before, providing our best chance yet at uncovering the complexities of solar activity in our own solar system and shedding light on the very nature of space and stars throughout the universe.

Together, NASA’s Parker Solar Probe and ESA’s (the European Space Agency) Solar Orbiter may resolve decades-old questions about the inner workings of our nearest star. Their comprehensive, up-close study of the Sun has important implications for how we live and explore: Energy from the Sun powers life on Earth, but it also triggers space weather events that can pose hazard to technology we increasingly depend upon.

Such space weather can disrupt radio communications, affect satellites and human spaceflight, and can severely damage our power grids. Such events also have a direct causal effect to Earth’s weather which can lead to extreme events causing vast destruction.  A better understanding of the fundamental processes at the Sun driving these events could improve predictions of when they’ll occur and how their effects may be felt on Earth.

“Our goal is to understand how the Sun works and how it affects the space environment to the point of predictability,” said Chris St. Cyr, Solar Orbiter project scientist at NASA’s Goddard Space Flight Center in Greenbelt, Maryland. “This is really a curiosity-driven science.”

Parker Solar Probe is slated to launch in the summer of 2018 and Solar Orbiter is scheduled to follow in 2020. These missions were developed independently, but their coordinated science objectives are no coincidence: Parker Solar Probe and Solar Orbiter are natural teammates.

Both missions will take a closer look at the Sun’s dynamic outer atmosphere, called the corona. From Earth, the corona is visible only during total solar eclipses, when the Moon blocks the Sun’s most intense light and reveals the outer atmosphere’s wispy, pearly-white structure. But the corona isn’t as delicate as it looks during a total solar eclipse. It can release a powerful punch of charged particles, and if Earth directed can have significant repercussions to Earth’s upper and lower atmospheres reflective of Rossby Waves which drive shifting jet streams and ocean currents.

Both Parker Solar Probe and Solar Orbiter will study the Sun’s most pervasive influence on the solar system: the solar wind. The Sun constantly exhales a stream of magnetized gas that fills the inner solar system, called solar wind. This solar wind interacts with magnetic fields, atmospheres, or even surfaces of worlds throughout the solar system. On Earth, this interaction can spark auroras and sometimes disrupt communications systems and power grids.

Data from previous missions have led scientists to believe the corona contributes to the processes that accelerate particles, driving the solar wind’s incredible speeds—which triple as it leaves the Sun and passes through the corona. Right now, the solar wind travels some 92 million miles by the time it reaches the spacecraft that measure it—plenty of time for this stream of charged gases to intermix with other particles traveling through space and lose some of its defining features. Parker Solar Probe will catch the solar wind just as it forms and leaves the corona, sending back to Earth some of the most pristine measurements of solar wind ever recorded. Solar Orbiter’s perspective, which will provide a good look at the Sun’s poles, will complement Parker Solar Probe’s study of the solar wind, because it allows scientists to see how the structure and behavior of the solar wind varies at different latitudes.

Solar Orbiter will also make use of its unique orbit to better understand the Sun’s magnetic fields; some of the Sun’s most interesting magnetic activity is concentrated at the poles. But because Earth orbits on a plane more or less in line with the solar equator, we don’t typically get a good view of the poles from afar. It’s a bit like trying to see the summit of Mount Everest from the base of the mountain.

That view of the poles will also go a long way toward understanding the overall nature of the Sun’s magnetic field, which is lively and extensive, stretching far beyond the orbit of Neptune. The Sun’s magnetic field is so far-reaching largely because of the solar wind: As the solar wind streams outward, it carries the Sun’s magnetic field with it, creating a vast bubble, called the heliosphere. Within the heliosphere, the solar wind determines the very nature of planetary atmospheres. The heliosphere’s boundaries are shaped by how the Sun interacts with interstellar space. Since Voyager 1’s passage through the heliopause in 2012, we know these boundaries dramatically protect the inner solar system from incoming galactic radiation.

It’s not yet clear how exactly the Sun’s magnetic field is generated or structured deep inside the Sun—though we do know intense magnetic fields around the poles drives variability on the Sun, causing solar flares and coronal mass ejections. Solar Orbiter will hover over roughly the same region of the solar atmosphere for several days at a time while scientists watch tension build up and release around the poles. Those observations may lead to better awareness of the physical processes that ultimately generate the Sun’s magnetic field.

Together, Parker Solar Probe and Solar Orbiter will refine our knowledge of the Sun and heliosphere. Along the way, it’s likely these missions will pose even more questions than they answer—a problem scientists are very much looking forward to.

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Waves Similar To Those Controlling Weather On Earth Have Now Been Found On The Sun

A team of scientists led by the Max Planck Institute for Solar System Research (MPS) and the University of Göttingen has discovered new waves of vorticity on the Sun. As described in today’s issue of Nature Astronomy, these Rossby waves propagate in the direction opposite to rotation, have lifetimes of several months, and maximum amplitudes at the Sun’s equator. For forty years scientists had speculated about the existence of such waves on the Sun, which should be present in every rotating fluid system. Now, they have been unambiguously detected and characterized for the first time. The solar Rossby waves are close relatives of the Rossby waves known to occur in the Earth’s atmosphere and oceans.

In almost every weather map of the Earth’s northern hemisphere atmospheric Rossby waves are a prominent feature. They appear as meanders in the jet stream separating cold polar air in the north from warmer subtropical air farther to the south. Sometimes these waves reach the equatorial regions and can even affect weather in Australia. In principle, waves of this type (often referred to as planetary waves) arise on every rotating sphere due to the Coriolis force. Saturn’s hexagon, a stable cloud pattern at the planet’s north pole, may also be an expression of these waves.

The existence of Rossby waves in stars was predicted about forty years ago. “Solar Rossby waves have very small amplitudes and periods of several months, thus they are extremely difficult to detect”, says Prof. Dr. Laurent Gizon, coordinator of the team that made the discovery and director at the MPS. The study required high-precision observations of the Sun over many years. The scientists from MPS analyzed a six-year dataset from the Heliospheric and Magnetic Imager (HMI) onboard NASA’s Solar Dynamics Observatory (SDO), in operation since 2010.

“The HMI images have sufficiently high spatial resolution to allow us to follow the movement of photospheric granules on the Sun’s visible surface”, says Dr. Björn Löptien, scientist at the MPS and first author of the article. These granules are small convective cells that are roughly 1500 kilometers in size on the solar surface. In their new study, the researchers used the granules as passive tracers to uncover the underlying, much larger vortex flows associated with the Rossby waves. In addition, methods of helioseismology were used to confirm the discovery and to study the Rossby waves in the solar interior at depths up to 20000 kilometers.

“All in all, we find large-scale waves of vorticity on the Sun that move in the direction opposite to rotation. That these waves are only seen in the equatorial regions is completely unexpected”, Gizon explains. The vorticity patterns are stable for several months. The researchers were able to determine the relationship between the waves’ frequency and wavelength for the first time – thus clearly identifying them as Rossby waves.

“Solar Rossby waves are gigantic in size, with wavelengths comparable to the solar radius”, Gizon explains. They are an essential component of the Sun’s internal dynamics because they contribute half of the Sun’s large-scale kinetic energy.

Fleet of NASA Spacecraft Finally Solve Mystery of the Earth’s Magnetic Field

A fleet of Nasa spacecraft have finally helped solve a long-standing mystery about the Earth’s magnetic field.

Scientists have used the data from the four spacecraft that are part of a Nasa mission to finally understand the energy in the swirling magnetic fields that surround the Earth.

That magnetic field helps protect us from solar wind, the stream of plasma coming from the Sun. As such, it protects life on Earth – and occasionally that solar weather breaks through and hits Earth hard, disrupting electrical and communications equipment on our planet, meaning that understanding how we are protected can be vitally important.

NASA’s Magnetospheric Multiscale (MMS) is flying four different spacecraft Earth to try and understand the phenomenon of magnetic reconnection. And it is that effect that explains the strange and intense energy contained in the magnetic fields around Earth.

The solar wind that comes from the Sun is made up of plasma – which is rare on Earth but makes up 99 per cent of the visible universe. That plasma becomes very turbulent when it arrives at the Earth’s magnetic field, in the “magnetosheath”.

Scientists now understand some of what causes that important turbulence, and where the energy and motion that erupt eventually go. The energy from the magnetic field is transferred to the particles, creating hot jets of plasma – and dissipating it into space.

The new study, published in Nature, marks the smallest scale observations of that event happening.

“Turbulence is one of the last great concepts in classical physics that we do not understand well, but we know it’s important in space as it redistributes energy,” said Jonathan Eastwood, one of the researchers involved in the study. “With this observation, we can now make new theories or models that will help us understand observations of other places like the Sun’s atmosphere and the magnetic environments of other planets.”

But the finding opens as many questions as it answers. Researchers now hope to create new models of the magnetosphere to account for how that magnetic reconnection could actually be happening.