Animation: Origins of Switchbacks

During Parker Solar Probe’s eighth orbit around the Sun, the spacecraft flew through structures in the corona called streamers. This movie shows that data from the WISPR instrument on Parker Solar Probe.Credit: NASA/Johns Hopkins APL/Naval Research Laboratory During encounters 8 and 9, Parker Solar Probe flew through structures in the corona called streamers. This movie shows that data from the WISPR instrument on Parker Solar Probe.Credit: NASA/Johns Hopkins APL/Naval Research Laboratory As Parker Solar Probe passed through the corona on encounter nine, the spacecraft flew by structures called coronal streamers. These structures can be seen as bright features moving upward in the upper images and angled downward in the lower row. Such a view is only possible because the spacecraft flew above and below the streamers inside the corona. Until now, streamers have only been seen from afar. They are visible from Earth during total solar eclipses.Credit: NASA/Johns Hopkins APL/Naval Research Laboratory As Parker Solar Probe passed through the corona on encounter nine, the spacecraft flew by structures called coronal streamers. These structures can be seen as bright features moving upward in the upper images and angled downward in the lower row. Such a view is only possible because the spacecraft flew above and below the streamers inside the corona. Until now, streamers have only been seen from afar. They are visible from Earth during total solar eclipses.Credit: NASA/Johns Hopkins APL/Naval Research Laboratory As Parker Solar Probe passed through the corona on encounter nine, the spacecraft flew by structures called coronal streamers. These structures can be seen as bright features moving upward in the upper images and angled downward in the lower row. Such a view is only possible because the spacecraft flew above and below the streamers inside the corona. Until now, streamers have only been seen from afar. They are visible from Earth during total solar eclipses.Credit: NASA/Johns Hopkins APL/Naval Research Laboratory As Parker Solar Probe passed through the corona on encounter nine, the spacecraft flew by structures called coronal streamers. These structures can be seen as bright features moving upward in the upper images and angled downward in the lower row. Such a view is only possible because the spacecraft flew above and below the streamers inside the corona. Until now, streamers have only been seen from afar. They are visible from Earth during total solar eclipses.Credit: NASA/Johns Hopkins APL/Naval Research Laboratory As Parker Solar Probe passed through the corona on encounter nine, the spacecraft flew by structures called coronal streamers. These structures can be seen as bright features moving upward in the upper images and angled downward in the lower row. Such a view is only possible because the spacecraft flew above and below the streamers inside the corona. Until now, streamers have only been seen from afar. They are visible from Earth during total solar eclipses.Credit: NASA/Johns Hopkins APL/Naval Research Laboratory As Parker Solar Probe passed through the corona on encounter nine, the spacecraft flew by structures called coronal streamers. These structures can be seen as bright features moving upward in the upper images and angled downward in the lower row. Such a view is only possible because the spacecraft flew above and below the streamers inside the corona. Until now, streamers have only been seen from afar. They are visible from Earth during total solar eclipses.Credit: NASA/Johns Hopkins APL/Naval Research Laboratory As Parker Solar Probe passed through the corona on encounter nine, the spacecraft flew by structures called coronal streamers. These structures can be seen as bright features moving upward in the upper images and angled downward in the lower row. Such a view is only possible because the spacecraft flew above and below the streamers inside the corona. Until now, streamers have only been seen from afar. They are visible from Earth during total solar eclipses.Credit: NASA/Johns Hopkins APL/Naval Research Laboratory For the first time in history, a spacecraft has touched the Sun. NASA’s Parker Solar Probe has now flown through the Sun’s upper atmosphere – the corona – and sampled particles and magnetic fields there. As Parker Solar Probe flew through the corona, its WISPR instrument captured images.The Wide-Field Imager for Parker Solar Probe (WISPR) is the only imaging instrument aboard the spacecraft. WISPR looks at the large-scale structure of the corona and solar wind before the spacecraft flies through it. About the size of a shoebox, WISPR takes images from afar of structures like coronal mass ejections, or CMEs, jets and other ejecta from the Sun. These structures travel out from the Sun and eventually overtake the spacecraft, where the spacecraft’s other instruments take in-situ measurements. WISPR helps link what’s happening in the large-scale coronal structure to the detailed physical measurements being captured directly in the near-Sun environment.To image the solar atmosphere, WISPR uses the heat shield to block most of the Sun’s light, which would otherwise obscure the much fainter corona. Specially designed baffles and occulters reflect and absorb the residual stray light that has been reflected or diffracted off the edge of the heat shield or other parts of the spacecraft.WISPR uses two cameras with radiation-hardened Active Pixel Sensor CMOS detectors. These detectors are used in place of traditional CCDs because they are lighter and use less power. They are also less susceptible to effects of radiation damage from cosmic rays and other high-energy particles, which are a big concern close to the Sun. The camera’s lenses are made of a radiation hard BK7, a common type of glass used for space telescopes, which is also sufficiently hardened against the impacts of dust.WISPR was designed and developed by the Solar and Heliophysics Physics Branch at the Naval Research Laboratory in Washington, D.C. (principal investigator Russell Howard), which will also develop the observing program. Related pages

Most of the magnetic field measured at Parker during this time is directed sunward (blue field lines and vectors). A switchback occurs when the field changes direction almost 180 degrees for a short period of time. FIELDS instrument magnetic vector data are projected from the spacecraft position as arrows. The arrows are colored deep blue for sunward vectors, deep red for anti-sunward, and in between for directions off from this line. The heliospheric magnetic field lines are represented as gold. Most of the magnetic field measured at Parker during this time is directed sunward (blue field lines and vectors). A switchback occurs when the field changes direction almost 180 degrees for a short period of time. FIELDS instrument magnetic vector data are projected from the spacecraft position as arrows. The arrows are colored deep blue for sunward vectors, deep red for anti-sunward, and in between for directions off from this line. The heliospheric magnetic field lines are represented as gold. A top-down view from the ecliptic pole of the orbit of Parker Solar Probe for Encounter 6. FIELDS instrument magnetic vector data are projected from the spacecraft position with arrows. The arrows are colored deep blue for sunward vectors, deep red for anti-sunward, and in between for directions off from this line. The heliospheric magnetic field lines are the gold lines, representing the propagation of the average field measured at Parker, propagated back to the solar photosphere. View of FIELDS instrument magnetic data measured at Parker Solar Probe during encounter 6. FIELDS instrument magnetic vector data are projected from the spacecraft position as arrows. The arrows are colored deep blue for sunward vectors, deep red for anti-sunward, and in between for directions off from this line. The heliospheric magnetic field lines are the gold lines, representing the propagation of the average field measured at Parker, propagated back to the solar photosphere. A top-down view from the ecliptic pole of the orbit of Parker Solar Probe for Encounter 6. A visualization from behind Parker Solar Probe as it approaches the Sun on Encounter 6. For a number of years, solar scientists have known about a phenomenon they called 'switchbacks'. Switchbacks are short-term 'flips' in the polarity of the magnetic field in the outflowing solar wind. Parker Solar Probe has detected these 'switchbacks' (Switchbacks Science: Explaining Parker Solar Probe’s Magnetic Puzzle), which appear to be more plentiful closer to the Sun.In the visualization above, Parker is passing through a region of inward bound magnetic flux (blue lines). This surrounding field is computed from a running average of the measurements by Parker, which are computing from the individual measurements at Parker's position (arrows projecting from the spacecraft position). For a brief time, these vectors flip direction, in this particular case changing color from blue to white and red, from the surrounding field, which is the signature of a switchback.Closer to the Sun, the average field lines trace back to coronal structures called pseudostreamers, that are magnetic structures which overlay and connect multiple pole magnetic regions. These regions also appear to correlate with where magnetic flux emerges between supergranule convection cells. Related pages

Split window view illustrating the orbit of Parker with the orbit trail colored based on the Mach number of the solar wind and the magnetic field lines (represented as gold) connecting back to the Sun. The Mach number drops below unity (one) when a field line transitions between two different coronal hole regions (the blue and red regions marked on the Sun). A visualization illustrating the orbit of Parker, orbit trail colored based on the Mach number of the solar wind, with the magnetic field lines (represented in gold) connecting back to the Sun. The Mach number drops below unity (one) when a field line transitions between two different coronal hole regions (the blue and red regions marked on the Sun). A visualization illustrating the magnetic field lines connecting Parker Solar Probe back to the Sun. When the Mach number in the solar wind drops below unity (one), the field line (gold) transitions between two different coronal hole regions (the blue and red regions marked on the Sun). A top-down view from the ecliptic pole of the orbit of Parker Solar Probe for Encounter 8. FIELDS instrument magnetic vector data are projected from the spacecraft position as arrows. The arrows are deep blue for sunward vectors, deep red for anti-sunward, and in between for directions off from this line. The heliospheric magnetic field lines are the gold lines, representing the propagation of the average field measured at Parker, propagated back to the solar photosphere. A top-down view from the ecliptic pole of the orbit of Parker Solar Probe for Encounter 8. View of FIELDS instrument data measured at Parker Solar Probe during encounter 8. FIELDS magnetic vector data are projected from the spacecraft position as arrows. The arrows are colored deep blue for sunward vectors, deep red for anti-sunward, and in between for directions off from this line. The heliospheric magnetic field lines are the gold lines, representing the propagation of the average field measured at Parker, propagated back to the solar photosphere. A visualization from behind Parker Solar Probe as it approaches the Sun on Encounter 8. The Sun's corona extends far beyond the solar surface, or photosphere and is considered the outer boundary of the Sun. It marks the transition to the solar wind which moves through the solar system. This limit is defined by the distance at which disturbances in the solar wind cannot propagate back to the solar surface. Those disturbances cannot propagate back towards the Sun if the outbound solar wind speed exceeds Mach one, the speed of 'sound' as defined for the solar wind. This distance forms an irregular 'surface' around the Sun called the Alfvén surface.Parker Solar Probe has now reached close enough to the Sun that it has begun to penetrate this Alfvén surface. From measurements of the solar wind plasma environment by the Parker's FIELDS and SWEAP instruments, scientists can compute the 'speed of sound' for the plasma, which exhibits brief periods when the Mach number drops below unity (one).At Parker's distance during encounter 8, the Mach number dropped below unity on several occasions. Propagating the magnetic field vector at Parker back to the solar photosphere revealed that these regions corresponded to significant changes in the magnetic field on the photosphere, particularly that fields lines of 'open' magnetic flux were transitioning from one location to another.In the visualizations below, we see the measured Mach number at Parker propagated along the orbit, with green representing Mach number greater than one, grey represents Mach number approximately one, and red represents Mach number less than one. When we trace the field lines at these moments back to the Sun, we see the field line jumping between isolated regions of 'open' magnetic flux - blue for inward magnetic flux and red for outbound magnetic flux. Related pages

Parker Solar Probe has now “touched the Sun”, passing through the Sun’s outer atmosphere, the corona for the first time in April 2021.Credit: NASA GSFC/CIL/Brian Monroe Parker Solar Probe has now “touched the Sun”, passing through the Sun’s outer atmosphere, the corona for the first time in April 2021.Credit: NASA/Johns Hopkins APL/Ben Smith Parker Solar Probe has now “touched the Sun”, passing through the Sun’s outer atmosphere, the corona for the first time in April 2021. The boundary that marks the edge of the corona is the Alfvén critical surface. Inside that surface, plasma is connected to the Sun by waves that travel back and forth to the surface. Beyond it, the Sun’s magnetic fields and gravity are too weak to contain the plasma and it becomes the solar wind, racing across the solar system so fast that waves within the wind cannot ever travel fast enough to make it back to the Sun. Credit: NASA/Johns Hopkins APL/Ben Smith The Alfvén critical surface marks the end of the solar atmosphere and beginning of the solar wind. Solar material with the energy to make it across that boundary (circle at right) becomes the solar wind, which drags the magnetic field of the Sun with it as it races across the solar system, to Earth and beyond. Beyond the Alfvén critical surface, the solar wind moves so fast that waves within the wind cannot ever travel fast enough to make it back to the Sun – severing their connection. Plasma within the corona (circle at left), is still connected to the Sun and waves in the plasma travel back and forth between the surface and upper corona.Credit: NASA GSFC/Johns Hopkins APL/Ben Smith As Parker Solar Probe passed through the corona on encounter nine, the spacecraft flew by structures called coronal streamers. These structures can be seen as bright features moving upward in the upper images and angled downward in the lower row. Such a view is only possible because the spacecraft flew above and below the streamers inside the corona. Until now, streamers have only been seen from afar. They are visible from Earth during total solar eclipses. Credit: NASA/Johns Hopkins APL/Naval Research Laboratory During Parker Solar Probe’s eighth orbit around the Sun, the spacecraft flew through structures in the corona called streamers.This movie shows that data from the WISPR instrument on Parker Solar Probe. Credit: NASA/Johns Hopkins APL/Naval Research Laboratory During encounters 8 and 9, Parker Solar Probe flew through structures in the corona called streamers.This movie shows that data from the WISPR instrument on Parker Solar Probe.Credit: NASA/Johns Hopkins APL/Naval Research Laboratory This model maps out a feature called a pseudostreamer that Parker Solar Probe flew through on its eighth encounter. To create the visualization, researchers used magnetic models to trace back particles in the solar wind measured by Parker to their origins on the solar surface. The colors show the speed of the particles compared to the speed of Alfvén waves, the fastest waves in the corona, with green being the particles flowing faster than Alfvén waves and purple slower. Credit: David Stansby A view of the Aug. 21, 2017, total solar eclipse from Madras, Oregon. On Parker Solar Probe’s eighth and ninth flybys, it passed through structures called coronal streamers. These features can be seen from Earth during total solar eclipses, such as in this image where they appear as bright streaks leading away from the Sun. Credit: NASA/Nat Gopalswamy Observed near Earth, the solar wind is a relatively uniform flow of plasma, with occasional turbulent tumbles. By that point it’s traveled over ninety million miles — and the signatures of the Sun's exact mechanisms for heating and accelerating the solar wind are wiped out. Closer to the solar wind's source, Parker Solar Probe is seeing a much different picture: a complicated, active system. These close-up views are helping scientists understand how the solar wind is accelerated to extreme speeds. Credit: NASA GSFC/CIL/Adriana Manrique Gutierrez As Parker Solar Probe ventures closer to the Sun, it’s crossing into uncharted regimes and making new discoveries. This image represents Parker Solar Probe's distances from the Sun for some of these milestones and discoveries.Credit: NASA GSFC/Mary P. Hrybyk-Keith Parker data found that the solar magnetic field embedded in the solar wind flips in the direction. These reversals — dubbed "switchbacks" — last anywhere from a few seconds to several minutes as they flow over Parker Solar Probe. During a switchback, the magnetic field whips back on itself until it is pointed almost directly back at the Sun.Credit: NASA GSFC/CIL/Adriana Manrique Gutierrez Parker Solar Probe has flown through several ‘switchbacks’ – tubes of fast solar wind emerging from coronal holes in the Sun’s upper atmosphere. Credit: NASA GSFC/CIL/Adriana Manrique Gutierrez Data from Parker Solar Probe has traced the origin of switchbacks – magnetic zig-zag structures in the solar wind – back to the solar surface. At the surface, magnetic funnels emerge from the photosphere between convection cell structures called supergranules. Switchbacks form inside the funnels and rise into the corona and are pushed out on the solar wind. Credit: NASA GSFC/CIL/Jonathan North Flying through several ‘switchbacks’ – magnetic zig-zag structures in the solar wind – close to the Sun, Parker Solar Probe gathered data allowing it to determine the switchbacks’ origins. Credit: NASA Goddard/CIL/Jonathan North Flying through several ‘switchbacks’ – magnetic zig-zag structures in the solar wind – close to the Sun, Parker Solar Probe gathered data allowing it to determine the switchbacks’ origins. Credit: NASA Goddard/CIL/Jonathan North NASA has a fleet of spacecraft strategically placed throughout our heliosphere -- from Parker Solar Probe at the Sun observing the very start of the solar wind, to satellites around Earth, to the farthest human-made object, Voyager, which is sending back observations on interstellar space. Each mission is positioned at a critical, well-thought out vantage point to observe and understand the flow of energy and particles throughout the solar system — all helping us untangle the effects of the star we live with.Credit: NASA GSFC/Jenny Mottar When flying past Venus in July 2020, Parker Solar Probe’s WISPR instrument, short for Wide-field Imager for Parker Solar Probe, detected a bright rim around the edge of the planet that may be nightglow — light emitted by oxygen atoms high in the atmosphere that recombine into molecules in the nightside. The prominent dark feature in the center of the image is Aphrodite Terra, the largest highland region on the Venusian surface. Bright streaks in WISPR, such as the ones seen here, are typically caused by a combination of charged particles — called cosmic rays — sunlight reflected by grains of space dust, and particles of material expelled from the spacecraft’s structures after impact with those dust grains. The number of streaks varies along the orbit or when the spacecraft is traveling at different speeds, and scientists are still in discussion about the specific origins of the streaks here. The dark spot appearing on the lower portion of Venus is an artifact from the WISPR instrument.Credit: NASA/Johns Hopkins APL/Naval Research Laboratory/Guillermo Stenborg and Brendan Gallagher Parker Solar Probe’s eighth flyby of the Sun started on April 24, 2021 at 23.2 million miles from the Sun. It reached perihelion on April 29, 2021 at 6.5 million miles from the Sun. Credit: NASA/Johns Hopkins APL/Steve Gribben One month after a flyby with Venus on October 16, 2021, Parker Solar Probe began its tenth solar encounter at 22.8 million miles from the Sun. On November 21, 2021 it reached perihelion for that encounter, putting it at just 5.3 million miles from the Sun. Credit: NASA/Johns Hopkins APL/Steve Gribben Parker Solar Probe has now “touched the Sun”, passing through the Sun’s outer atmosphere, the corona for the first time in April 2021. This historic closest approach to the Sun is allowing Parker to gather data that’s helping scientists unravel some of the biggest questions about our star and its influence on the solar system. Credit: NASA/Johns Hopkins APL This conceptual image shows Parker Solar Probe about to enter the solar corona.Credit: NASA/Johns Hopkins APL/Ben Smith NASA’s Parker Solar Probe has now done what no spacecraft has done before—it has officially touched the Sun. Launched in 2018 to study the Sun’s biggest mysteries, the spacecraft has now grazed the edge of the solar atmosphere and gathered new close-up observations of our star. This is allowing us to see the Sun as never before—including the findings in two new papers, which were presented at AGU, that are helping scientists answer fundamental questions about the Sun.PANELISTSDr. Nicola Fox• Heliophysics Division Director of the Science Mission Directorate at NASA HeadquartersDr. Nour Raouafi• Project Scientist for NASA’s Parker Solar Probe• The Johns Hopkins Applied Physics Laboratory Dr. Justin Kasper• Principal Investigator for Solar Wind Electrons Alphas and Protons (SWEAP) Investigation on Parker Solar Probe • BWX Technologies, Inc., University of MichiganProf. Stuart D. Bale• Principal Investigator for Fields Experiment (FIELDS) on Parker Solar Probe • University of California, Berkeley Dr. Kelly Korreck• Program Scientist at NASA Headquarters• Smithsonian Astrophysical Observatory For More InformationSee [https://www.nasa.gov/feature/goddard/2021/nasa-enters-the-solar-atmosphere-for-the-first-time-bringing-new-discoveries](https://www.nasa.gov/feature/goddard/2021/nasa-enters-the-solar-atmosphere-for-the-first-time-bringing-new-discoveries) Related pages

Parker Solar Probe has now “touched the Sun”, passing through the Sun’s outer atmosphere, the corona for the first time in April 2021. The boundary that marks the edge of the corona is the Alfvén critical surface. Inside that surface (circle at left), plasma is connected to the Sun by waves that travel back and forth to the surface. Beyond it (circle at right), the Sun’s magnetic fields and gravity are too weak to contain the plasma and it becomes the solar wind, racing across the solar system so fast that waves within the wind cannot ever travel fast enough to make it back to the Sun. Credit: NASA/Johns Hopkins APL/Ben Smith STILL IMAGEParker Solar Probe has now “touched the Sun”, passing through the Sun’s outer atmosphere, the corona for the first time in April 2021.Credit: NASA/Johns Hopkins APL/Ben Smith STILL IMAGEThis conceptual image shows Parker Solar Probe about to enter the solar corona.Credit: NASA/Johns Hopkins APL/Ben Smith STILL IMAGEThis conceptual image shows Parker Solar Probe about to enter the solar corona.Credit: NASA/Johns Hopkins APL/Ben Smith For the first time in history, a spacecraft has touched the Sun. NASA’s Parker Solar Probe has now flown through the Sun’s upper atmosphere – the corona – and sampled particles and magnetic fields there. The new milestone marks one major step for Parker Solar Probe and one giant leap for solar science. Just as landing on the Moon allowed scientists to understand how it was formed, touching the very stuff the Sun is made of will help scientists uncover critical information about our closest star and its influence on the solar system. On April 28, 2021, during its eighth flyby of the Sun, Parker Solar Probe encountered the specific magnetic and particle conditions at 18.8 solar radii (8.127 million miles) above the solar surface that told scientists it had crossed the Alfvén critical surface for the first time and finally entered the solar atmosphere.More information here. For More InformationSee [https://www.nasa.gov/feature/goddard/2021/nasa-enters-the-solar-atmosphere-for-the-first-time-bringing-new-discoveries](https://www.nasa.gov/feature/goddard/2021/nasa-enters-the-solar-atmosphere-for-the-first-time-bringing-new-discoveries) Related pages