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  • richardmitnick 2:00 pm on January 17, 2022 Permalink | Reply
    Tags: "New research may help scientists unravel the physics of the solar wind", , , The School of Physics and Astronomy at the University of Minnesota-Twin Cities (US), The solar wind – a constant powerful stream of charged particles or plasma spraying out in every direction from the Sun., The University of Minnesota College of Science and Engineering (US)   

    From The University of Minnesota College of Science and Engineering (US) and The School of Physics and Astronomy at the University of Minnesota-Twin Cities (US): “New research may help scientists unravel the physics of the solar wind” 

    From The University of Minnesota College of Science and Engineering (US)




    The School of Physics and Astronomy at the University of Minnesota-Twin Cities (US)



    The University of Minnesota Twin Cities (US)


    Understanding the solar wind can help scientists predict how it will affect Earth’s satellites and astronauts in space.

    NASA Parker Solar Probe Plus named to honor Pioneering Physicist Eugene Parker. The Johns Hopkins University Applied Physics Lab (US).

    A new study led by University of Minnesota Twin Cities researchers, using data from NASA’s Parker Solar Probe, provides insight into what generates and accelerates the solar wind, a stream of charged particles released from the sun’s corona. Understanding how the solar wind works can help scientists predict “space weather,” or the response to solar activity—such as solar flares—that can impact both astronauts in space and much of the technology people on Earth depend on.

    The paper is published in The Astrophysical Journal Letters.

    The scientists used data gathered from Parker Solar Probe, which launched in 2018 with the goal to help scientists understand what heats the Sun’s corona (the outer atmosphere of the sun) and generates the solar wind. To answer these questions, scientists need to understand the ways in which energy flows from the sun. The latest round of data was obtained in August 2021 at a distance of 4.8 million miles from the sun—the closest a spacecraft has ever been to the star.

    Previous research has indicated that in the solar wind, at distances from about 35 solar radii (one solar radius is a little more than 432,000 miles) out to the Earth’s orbit at about 215 solar radii, electromagnetic waves called “whistler” waves help regulate the heat flux, one form of energy flow. In this new study, the University of Minnesota-led research team discovered that in a region closer to the sun, inside around 28 solar radii, there are no whistler waves.

    Instead, the researchers saw a different kind of wave that was electrostatic instead of electromagnetic. And in that same region, they noticed something else: the electrons showed the effect of an electric field created in part by the pull of the sun’s gravity, similar to what happens at the Earth’s poles where a “polar wind” is accelerated.

    “What we found is that when we get inside 28 solar radii, we lose the whistlers. That means the whistlers can’t be doing anything to control the heat flux in that region,” said Cynthia Cattell, lead author on the paper and a professor in The School of Physics and Astronomy at the University of Minnesota-Twin Cities (US). “This result was very, very surprising to people. It has impacts not only for understanding the solar wind and the winds of other stars, but it’s also important for understanding the heat flux of a lot of other astrophysical systems to which we can’t send satellites—things like how star systems form.”

    Learning about the solar wind is also important to scientists for other reasons. For one, it can disturb earth’s magnetic field, generating “space weather” events that can make satellites malfunction, impact communication and GPS signals, and cause power outages on Earth at northern latitudes like Minnesota. The energetic particles that propagate through the solar wind can also be harmful to astronauts traveling in space.

    “Scientists want to be able to predict space weather,” Cattell explained. “And if you don’t understand the details of energy flow close to the sun, then you can’t predict how fast the solar wind will be moving or what its density will be when it reaches Earth. These are some of the properties that determine how solar activity affects us.”

    In late 2024, the Parker Solar Probe will fly to an even closer distance of 3.8 million miles from the sun. Moving forward, Cattell and her colleagues are excited to see the next round of data from the spacecraft. Their next goal will be to figure out why this absence of whistler waves exists so close to the sun, how the electrons accelerated by the gravity-associated electric field might excite other waves, and how that impacts the solar wind.

    In addition to Cattell, the research team included University of Minnesota School of Physics and Astronomy researchers Elizabeth Hanson, John Dombeck, research director Keith Goetz, and Ph.D. alumnus Mike Johnson; NASA Goddard Space Flight Center (US) researcher Aaron Breneman; The University of Iowa (US) associate professor Jasper Halekas; The University of California-Berkeley (US) professor Stuart Bale, The University of California-Berkeley (US) Space Sciences Laboratory associate researcher Marc Pulupa, project scientist David Larson, and assistant researcher Phyllis Whittlesey; The University of Orléans [Université d’Orléans](FR) professor Thierry Dudok de Wit; The West Virginia University(US) assistant professor Katherine Goodrich; The University of Colorado-Boulder (US) assistant professor David Malaspina; The Harvard-Smithsonian Center for Astrophysics(US) researchers Tony Case and Michael Stevens; and The University of Michigan(US) professor Justin C. Kasper.

    The research was funded by NASA, and the simulation work was supported by the Minnesota Supercomputing Institute on the University of Minnesota Twin Cities campus. Parker Solar Probe is part of NASA’s Living with a Star program to explore aspects of the Sun-Earth system that directly affect life and society. The program is managed by NASA’s Goddard Space Flight Center for the Heliophysics Division of NASA’s Science Mission Directorate. The Johns Hopkins Applied Physics Laboratory in Laurel, Maryland, built and operates the Parker Solar Probe spacecraft and manages the mission for NASA.

    See the full article here .


    Please help promote STEM in your local schools.

    Stem Education Coalition


    The College of Science and Engineering (CSE) is one of the colleges of the University of Minnesota in Minneapolis, Minnesota. On July 1, 2010, the college was officially renamed from the Institute of Technology (IT). It was created in 1935 by bringing together the University’s programs in engineering, mining, architecture, and chemistry. Today, CSE contains 12 departments and 24 research centers that focus on engineering, the physical sciences, and mathematics.


    Aerospace Engineering and Mechanics
    Biomedical Engineering
    Chemical Engineering and Materials Science
    Civil, Environmental, and GeoEngineering
    Computer Science and Engineering
    Earth Sciences (formerly called Geology and Geophysics)
    Electrical and Computer Engineering
    Industrial and Systems Engineering
    Mechanical Engineering
    Physics and Astronomy
    Additionally, CSE pairs with other departments at the University to offer degree-granting programs in:
    Bioproducts and Biosystems Engineering, with CFANS (formerly two departments: Biosystems and Agricultural Engineering, and Bio-based Products)
    And two other CSE units grant advanced degrees:
    Technological Leadership Institute (formerly Center for the Development of Technological Leadership)
    History of Science and Technology

    Research centers

    BioTechnology Institute
    Characterization Facility
    Charles Babbage Institute – CBI website
    Digital Technology Center
    William I. Fine Theoretical Physics Institute
    Industrial Partnership for Research in Interfacial and Materials Engineering
    Institute for Mathematics and its Applications
    Minnesota Nano Center
    NSF Engineering Research Center for Compact and Efficient Fluid Power
    NSF Materials Research Science and Engineering Center
    NSF Multi-Axial Subassemblage Testing (MAST) System
    NSF National Center for Earth-surface Dynamics (NCED)
    The Polar Geospatial Center
    Center for Transportation Studies
    University of Minnesota Supercomputing Institute
    GroupLens Center for Social and Human-Centered Computing

    Educational centers

    History of Science and Technology
    School of Mathematics Center for (K-12) Educational Programs
    Technological Leadership Institute
    UNITE Distributed Learning


    The University of Minnesota Twin Cities is a public research university in Minneapolis and Saint Paul, MN. The Twin Cities campus comprises locations in Minneapolis and St. Paul approximately 3 miles (4.8 km) apart, and the St. Paul location is in neighboring Falcon Heights. The Twin Cities campus is the oldest and largest in The University of Minnesota (US) system and has the sixth-largest main campus student body in the United States, with 51,327 students in 2019-20. It is the flagship institution of the University of Minnesota System, and is organized into 19 colleges, schools, and other major academic units.

    The Minnesota Territorial Legislature drafted a charter for The University of Minnesota as a territorial university in 1851, seven years before Minnesota became a state. Today, the university is classified among “R1: Doctoral Universities – Very high research activity”. The University of Minnesota is a member of The Association of American Universities (US) and is ranked 17th in research activity, with $954 million in research and development expenditures in the fiscal year 2018. In 2001, the University of Minnesota was included in a list of Public Ivy universities, which includes publicly funded universities thought to provide a quality of education comparable to that of the Ivy League.

    University of Minnesota faculty, alumni, and researchers have won 26 Nobel Prizes and three Pulitzer Prizes. Among its alumni, the university counts 25 Rhodes Scholars, seven Marshall Scholars, 20 Truman Scholars, and 127 Fulbright recipients. The University of Minnesota also has Guggenheim Fellowship, Carnegie Fellowship, and MacArthur Fellowship holders, as well as past and present graduates and faculty belonging to The American Academy of Arts and Sciences (US), The National Academy of Sciences (US), The National Academy of Medicine (US), and The National Academy of Engineering(US). Notable University of Minnesota alumni include two vice presidents of the United States, Hubert Humphrey and Walter Mondale, and Bob Dylan, who received the 2016 Nobel Prize in Literature.

    The Minnesota Golden Gophers compete in 21 intercollegiate sports in the NCAA Division I Big Ten Conference and have won 29 national championships. As of 2021, Minnesota’s current and former students have won a total of 76 Olympic medals.

    The University of Minnesota was founded in Minneapolis in 1851 as a college preparatory school, seven years prior to Minnesota’s statehood. It struggled in its early years and relied on donations to stay open from donors including South Carolina Governor William Aiken Jr.

    In 1867, the university received land grant status through the Morrill Act of 1862.

    An 1876 donation from flour miller John S. Pillsbury is generally credited with saving the school. Since then, Pillsbury has become known as “The Father of the University.” Pillsbury Hall is named in his honor.


    The university is organized into 19 colleges, schools, and other major academic units:

    Center for Allied Health Programs
    College of Biological Sciences
    College of Continuing and Professional Studies
    School of Dentistry
    College of Design
    College of Education and Human Development
    College of Food, Agricultural and Natural Resource Sciences
    Graduate School
    Law School
    College of Liberal Arts
    Carlson School of Management
    Medical School
    School of Nursing
    College of Pharmacy
    Hubert H. Humphrey School of Public Affairs
    School of Public Health
    College of Science and Engineering
    College of Veterinary Medicine

    Institutes and centers

    Six university-wide interdisciplinary centers and institutes work across collegiate lines:

    Center for Cognitive Sciences
    Consortium on Law and Values in Health, Environment, and the Life Sciences
    Institute for Advanced Study, University of Minnesota
    Institute for Translational Neuroscience
    Institute on the Environment
    Minnesota Population Center

    In 2021, the University of Minnesota was ranked as 40th best university in the world by The Academic Ranking of World Universities (ARWU), which assesses academic and research performance. The same 2021 ranking by subject placed The University of Minnesota’s ecology program as 2nd best in the world, its management program as 10th best, its biotechnology program as 11th best, mechanical engineering and medical technology programs as 14th best, law and psychology programs as 19th best, and veterinary sciences program as 20th best. The Center for World University Rankings (CWUR) for 2021-22 ranked Minnesota 46th in the world and 26th in the United States. The 2021 Nature Index, which assesses the institutions that dominate high quality research output, ranked Minnesota 53rd in the world based on research publication data from 2020. U.S. News and World Report ranked Minnesota as the 47th best global university for 2021. The 2022 Times Higher Education World University Rankings placed Minnesota 86th worldwide, based primarily on teaching, research, knowledge transfer and international outlook.

    In 2021, The University of Minnesota was ranked as the 24th best university in the United States by The Academic Ranking of World Universities, and 20th in the United States in Washington Monthly’s 2021 National University Rankings. The University of Minnesota’s undergraduate program was ranked 68th among national universities by U.S. News and World Report for 2022, and 26th in the nation among public colleges and universities. The same publication ranked The University of Minnesota’s graduate Carlson School of Management as 28th in the nation among business schools, and 6th in the nation for its information systems graduate program. Other graduate schools ranked highly by U.S. News and World Report for 2022 include The University of Minnesota Law School at 22nd, The University of Minnesota Medical School, which was 4th for family medicine and 5th for primary care, The University of Minnesota College of Pharmacy, which ranked 3rd, The Hubert H. Humphrey School of Public Affairs, which ranked 9th, The University of Minnesota College of Education and Human Development, which ranked 10th for education psychology and special education, and The University of Minnesota School of Public Health, which ranked 10th.

    In 2019, The Center for Measuring University Performance ranked The University of Minnesota 16th in the nation in terms of total research, 29th in endowment assets, 22nd in annual giving, 28th in the number of National Academies of Sciences, Engineering and Medicine memberships, 18th in its number of faculty awards, and 14th in its number of National Merit Scholars. Minnesota is listed as a “Public Ivy” in 2001 Greenes’ Guides The Public Ivies: America’s Flagship Public Universities.



    The Minnesota Daily has been published twice a week during the normal school season since the fall semester 2016. It is printed weekly during the summer. The Daily is operated by an autonomous organization run entirely by students. It was first published on May 1, 1900. Besides everyday news coverage, the paper has also published special issues, such as the Grapevine Awards, Ski-U-Mah, the Bar & Beer Guide, Sex-U-Mah, and others.

    A long-defunct but fondly remembered humor magazine, Ski-U-Mah, was published from about 1930 to 1950. It launched the career of novelist and scriptwriter Max Shulman.

    A relative newcomer to the university’s print media community is The Wake Student Magazine, a weekly that covers UMN-related stories and provides a forum for student expression. It was founded in November 2001 in an effort to diversify campus media and achieved student group status in February 2002. Students from many disciplines do all of the reporting, writing, editing, illustration, photography, layout, and business management for the publication. The magazine was founded by James DeLong and Chris Ruen. The Wake was named the nation’s best campus publication (2006) by The Independent Press Association.

    Additionally, The Wake publishes Liminal, a literary journal begun in 2005. Liminal was created in the absence of an undergraduate literary journal and continues to bring poetry and prose to the university community.

    The Wake has faced a number of challenges during its existence, due in part to the reliance on student fees funding. In April 2004, after the Student Services Fees Committee had initially declined to fund it, the needed $60,000 in funding was restored, allowing the magazine to continue publishing. It faced further challenges in 2005, when its request for additional funding to publish weekly was denied and then partially restored.

    In 2005 conservatives on campus began formulating a new monthly magazine named The Minnesota Republic. The first issue was released in February 2006, and funding by student service fees started in September 2006.


    The campus radio station, KUOM “Radio K,” broadcasts an eclectic variety of independent music during the day on 770 kHz AM. Its 5,000-watt signal has a range of 80 miles (130 km), but shuts down at dusk because of Federal Communications Commission regulations. In 2003, the station added a low-power (8-watt) signal on 106.5 MHz FM overnight and on weekends. In 2005, a 10-watt translator began broadcasting from Falcon Heights on 100.7 FM at all times. Radio K also streams its content at http://www.radiok.org. With roots in experimental transmissions that began before World War I, the station received the first AM broadcast license in the state on January 13, 1922, and began broadcasting as WLB, changing to the KUOM call sign about two decades later. The station had an educational format until 1993, when it merged with a smaller campus-only music station to become what is now known as Radio K. A small group of full-time employees are joined by over 20 part-time student employees who oversee the station. Most of the on-air talent consists of student volunteers.


    Some television programs made on campus have been broadcast on local PBS station KTCI channel 17. Several episodes of Great Conversations have been made since 2002, featuring one-on-one discussions between University faculty and experts brought in from around the world. Tech Talk was a show meant to help people who feel intimidated by modern technology, including cellular phones and computers.

  • richardmitnick 6:42 pm on January 2, 2021 Permalink | Reply
    Tags: As the first man-made objects to leave our Solar System the Voyager spacecrafts 1 and 2 are venturing into uncharted territory billions of miles from home. No other spacecraft have travelled as far., Astronomers can only receive Voyager’s information thanks to a massive array of satellite dishes and advanced technology not even existent when the spacecraft were launched., , , , , By keeping the interstellar medium at bay the solar wind also keeps out a life-threatening bombardment of radiation and deadly high-energy particles – such as cosmic rays., , , Interstellar space, Kuiper Belt and Oort Cloud, , NASA Voyager 1 and 2-built and launched in 1970s., NASA/IBEX mission, Scientists have been building up a picture of what the interstellar medium is made of thanks largely to observations with radio and X-ray telescopes., The solar wind – a constant powerful stream of charged particles or plasma spraying out in every direction from the Sun.   

    From BBC (UK): “The weird space that lies outside our Solar System” 

    From BBC (UK)

    Credit: NASA/STScI/Aura.

    8th September 2020 [Just now in social media.]
    Patchen Barss

    The mysterious dark vacuum of interstellar space is finally being revealed by two intrepid spacecraft that have become the first human-made objects to leave our Solar System.

    Heliosphere-heliopause showing positions of two Voyager spacecraft. Credit: NASA.

    Far from the protective embrace of the Sun, the edge of our Solar System would seem to be a cold, empty, and dark place. The yawning space between us and the nearest stars was for a long time thought to be a frighteningly vast expanse of nothingness.

    Until recently, it was somewhere that humankind could only peer into from afar. Astronomers paid it only passing attention, preferring instead to focus their telescopes on the glowing masses of our neighbouring stars, galaxies and nebula.

    But two spacecraft, built and launched in 1970s, have for the past few years been beaming back our first glimpses from this strange region we call interstellar space.

    NASA/Voyager 1.

    NASA/Voyager 2.

    As the first man-made objects to leave our Solar System, they are venturing into uncharted territory, billions of miles from home. No other spacecraft have travelled as far.

    And they have revealed that beyond the boundaries of our solar system lies an invisible region of chaotic, frothing activity.

    “When you look at different parts of the electromagnetic spectrum, that area of space is very different from the blackness we perceive with our eyes,” says Michele Bannister, an astronomer at the University of Canterbury in Christchurch, New Zealand, who studies the outer reaches of the Solar System. “Magnetic fields are fighting and pushing and tied up with each other. The image you should have is like the plunge pool under Niagara Falls.”

    Explosions like supernovae fling cosmic rays out in all directions into interstellar space Credit: NASA/ESA Hubble.

    Instead of tumbling water, however, the turbulence is the result of the solar wind – a constant, powerful stream of charged particles, or plasma, spraying out in every direction from the Sun – as it crashes into a cocktail of gas, dust, and cosmic rays that blows between star systems, known as the “interstellar medium”.

    Scientists have been building up a picture of what the interstellar medium is made of over the past century, thanks largely to observations with radio and X-ray telescopes.

    ESO/NRAO/NAOJ ALMA Array in Chile in the Atacama at Chajnantor plateau, at 5,000 metres.

    NRAO Karl G Jansky Very Large Array, located in central New Mexico on the Plains of San Agustin, between the towns of Magdalena and Datil, ~50 miles (80 km) west of Socorro. The VLA comprises twenty-eight 25-meter radio telescopes.

    ASTRON LOFAR Radio Antenna Bank, Netherlands.

    SKA Murchison Widefield Array, Boolardy station in outback Western Australia, at the Murchison Radio-astronomy Observatory (MRO).

    Australian Square Kilometre Array Pathfinder (ASKAP) is a radio telescope array located at Murchison Radio-astronomy Observatory (MRO) in the Australian Mid West. ASKAP consists of 36 identical parabolic antennas, each 12 metres in diameter, working together as a single instrument with a total collecting area of approximately 4,000 square metres.

    NASA Chandra X-ray Space Telescope

    ESA/XMM Newton X-ray telescope (EU).

    NASA/DTU/ASI NuSTAR X-ray telescope.

    They have revealed it is composed of extremely diffuse ionised hydrogen atoms, dust, and cosmic rays interspersed with dense molecular clouds of gas thought to be the birthplace of new stars.

    But its exact nature just outside our solar system has been largely a mystery, principally because the Sun, all eight planets and a distant disc of debris known as the Kuiper Belt, are all contained within a giant protective bubble formed by the solar wind, known as the heliosphere [above]. As the Sun and its surrounding planets hurtle through the galaxy, this bubble buffets against the interstellar medium like an invisible shield, keeping out the majority of harmful cosmic rays and other material.

    Kuiper Belt. Minor Planet Center

    But its life-saving properties also make it more difficult to study what lies beyond the bubble.

    Magnetosphere of Earth, original bitmap from NASA. SVG rendering by Aaron Kaase.

    Even determining its size and shape is difficult from within.

    “It’s like you’re inside your home and you want to know what it looks like. You have to go outside and take a look to really tell,” says Elena Provornikova, a postdoctoral researcher at the Johns Hopkins University Applied Physics Laboratory. “The only way to get an idea is to travel far away from the Sun, look back, and take an image from outside the heliosphere.”

    This is no simple task. Compared to the whole of the Milky Way, our Solar System looks smaller than a grain of rice floating in the middle of the Pacific. And yet, the outer edge of the heliosphere is still so distant that it took more than 40 years for the Voyager 1 and Voyager 2 spacecraft [both above] to reach it as they flew from Earth.

    Voyager 1, which took a more direct route through the Solar System, passed out into interstellar space in 2012, before Voyager 2 joined it in 2018. Currently around 13 billion and 11 billion miles from Earth respectively, they are now drifting out, ever further into the space beyond our Solar System, sending back more data as they do.

    The car-sized Voyager spacecraft were launched in 1977 and are now beaming back data from interstellar space. Credit: NASA/JPL-Caltech.

    What these two aging probes revealed about the boundary between the heliosphere and the interstellar medium has provided fresh clues about how our Solar System formed, and how life on Earth is even possible. Far from being a distinct boundary, the very edge of our Solar System actually churns with roiling magnetic fields, clashing stellar windstorms, storms of high energy particles and swirling radiation.

    The size and shape of the heliosphere bubble alters as the Sun’s output changes, and as we pass through different regions of the interstellar medium. When the solar wind rises or falls, it changes the outward pressure on the bubble.

    In 2014, the Sun’s activity surged, sending what amounted to a solar-wind hurricane sweeping out into space. The blast quickly washed over Mercury and Venus at close to 800 km per second (497 miles per second). After two days and 150 million km (93.2 million miles), it enveloped Earth. Fortunately, our planet’s magnetic field [magnetosphere above] shielded us from its powerful, damaging radiation.

    The gust pushed past Mars a day later and carried on through the asteroid belt toward the distant gas giants – Jupiter, Saturn, Uranus and after more than two months, Neptune, which orbits nearly 4.5 billion km (2.8 billion miles) from the Sun.

    After more than six months, the wind finally reached a point more than 13 billion km (8.1 billion miles) from the Sun known as the “termination shock”. Here, the Sun’s magnetic field, which propels the solar wind, becomes weak enough for interstellar medium to push against it.

    The solar wind gust emerged from the termination shock traveling at less than half its previous speed – the hurricane downgraded to a tropical storm. Then in late 2015, it overtook the irregularly shaped form of Voyager 2, which is about the size of a small car. The plasma surge was detected by Voyager’s 40-year-old sensing technologies, powered by a slowly decaying plutonium battery.

    The probe beamed data back toward Earth, which even at the speed of light took 18 hours to reach us. Astronomers could only receive Voyager’s information thanks to a massive array of 70-metre satellite dishes and advanced technology that hadn’t been imagined, let alone invented, when the probe left Earth in 1977.

    NASA Canberra, AU, Deep Space Network. Credit: NASA.

    NASA Deep Space Network dish, Goldstone, CA, USA. Altitude 2,950 ft (900 m). Credit: NASA.

    NASA Deep Space Network Madrid Spain. Credit: NASA.

    The Sun produces a constant barrage of high energy particles known as the solar wind, which can rise and fall with the activity of our star (Credit: NASA)

    The solar wind surge reached Voyager 2 while it was still just inside our Solar System. A little more than a year later, the last gasps of the dying wind reached Voyager 1, which had crossed over into interstellar space in 2012.

    The different routes taken by the two probes meant one was about 30 degrees above the solar plane, the other the same amount below. The solar wind burst reached them in different regions at different times, which provided useful clues about the nature of the heliopause.

    The data revealed that the turbulent boundary is millions of kilometres thick. It covers billions of square kilometres around the surface of the heliosphere.

    The heliosphere is also unexpectedly large, which suggests that the interstellar medium in this part of the galaxy is less dense than people thought. The Sun cuts a path through interstellar space like a boat moving through water, creating a “bow wave” and stretching a wake out behind it, possibly with a tail (or tails) in shapes similar to those of comets. Both Voyagers exited through the “nose” of the heliosphere, and so provided no information about the tail.

    “The estimate from the Voyagers is that the heliopause is about one astronomical unit thick (93 million miles, which is the average distance between the Earth and the Sun),” says Provornikova. “It’s not really a surface. It’s a region with complex processes. And we don’t know what’s going on there.”

    Not only do solar and interstellar winds create a turbulent tug of war in the boundary region, but particles appear to swap charges and momentum. As a result, a portion of the interstellar medium becomes converted to solar wind, actually increasing the outward push of the bubble.

    And while a solar wind surge can provide interesting data, it seems to have a surprisingly small effect on the bubble’s overall size and shape. It appears that what happens outside the heliosphere matters much more than what happens within. The solar wind can wax or wane over time without appearing to dramatically affect the bubble. But if that bubble moves into a region of the galaxy with denser or less dense interstellar wind, then it will shrink or grow.

    But many questions remain unanswered, including those around exactly how typical our protective solar-wind bubble might be.

    The Sun’s heliosphere forms a long tail as it pushes its way through the interstellar medium on its journey around the galaxy. Credit: NASA.

    Provornikova says understanding more about our own heliosphere can tell us more about whether we’re alone in the universe.

    “What we study in our own system will tell us about the conditions for the development of life in other stellar systems,” she says.

    This is largely because by keeping the interstellar medium at bay, the solar wind also keeps out a life-threatening bombardment of radiation and deadly high-energy particles – such as cosmic rays – from deep space.

    Cosmic rays produced by high-energy astrophysics sources (ASPERA collaboration – AStroParticle ERAnet)

    Cosmic rays are protons and atomic nuclei streaming through space at nearly the speed of light. They can be generated when stars explode, when galaxies collapse into black holes, and other cataclysmic cosmic events. The region outside our Solar System is thick with a steady rain of these high-speed subatomic particles, which would be powerful enough to cause deadly radiation poisoning on a less sheltered planet.

    “Voyager definitively said that 90% of this radiation gets filtered out by the Sun,” says Jamie Rankin, a heliophysics researcher at Princeton University, and the first person to write a PhD thesis based on the Voyagers’ interstellar data. “If we didn’t have the solar wind protecting us, I don’t know if we’d be alive.”

    Three additional NASA probes will soon join the Voyagers in interstellar space, although two have already run out of power and stopped returning data. These few tiny pinpricks in the giant boundary will only ever provide limited information on their own. Fortunately, more expansive observation can be done closer to home.

    NASA’s International Boundary Explorer (IBEX), a tiny satellite that has orbited Earth since 2008, detects particles called “energetic neutral atoms” that pass through the interstellar boundary.


    IBEX creates three dimensional maps of the interactions happening all around the edge of the heliosphere.

    The IBEX mission has detected a ribbon of high energy atoms being reflected back from the edge of the heliosphere by the galactic magnetic field (Credit: NASA)

    “You can think of IBEX maps as sort of the ‘Doppler radar’ and the Voyagers as on-the-ground weather stations,” says Rankin. She has used data from Voyagers, IBEX, and other sources to analyse smaller surges in the solar wind, and is currently working on a paper based on the much larger blast that began in 2014. Already, the evidence shows that the heliosphere was shrinking when Voyager 1 passed the boundary, but was expanding again when Voyager 2 crossed over.

    “It’s quite a dynamic boundary,” she says. “It’s pretty amazing that this discovery was captured in IBEX’s 3D maps, which enabled us to track the local responses from the Voyagers at the same time.”

    IBEX has revealed just how dynamic the boundary can be. In its first year it detected a giant ribbon of energetic atoms snaking across the boundary that changed over time, with features appearing and disappearing as briefly as six months. The ribbon turns out to be a region at the nose of the heliosphere where solar wind particles bounce off the galactic magnetc field and are reflected back into the Solar System.

    When Voyager 2 left the solar system it detected a dramatic spike in cosmic rays from which the heliosphere protects us. Credit: NASA/JPL-Caltech/GSFC.

    But there is a twist to the Voyager story. Although they have left the heliosphere, they are still within range of many of our Sun’s other influences. The Sun’s light, for instance, would be visible to the naked human eye from other stars. Our star’s gravity also extends well beyond the heliosphere, holding in place a distant, sparse sphere of ice, dust, and space debris known as the Oort Cloud.

    Voyager 1 crossed over into interstellar space in 2012 100 Astronomical Units from the Sun but it still has the vast Oort Cloud ahead of it. Credit: NASA/JPL-Caltech.

    Oort objects still orbit the Sun, despite floating far out in interstellar space. While some comets have orbits that reach all the way out to the Oort cloud, a region 186-930 billion miles (300-1,500 billion km) is generally considered too distant for us to send probes of our own.

    These distant objects have barely changed since the Solar System began, and may hold keys to everything from how planets form to how likely life is to arise in our universe. And with each wave of new data, new mysteries and questions also emerge.

    Provornikova says there may be a blanket of hydrogen covering some or all of the heliosphere, whose effects have yet to be decoded. In addition, the heliosphere appears to be careening into an interstellar cloud of particles and dust left over from ancient cosmic events whose effects on the boundary – and on those of us who live within it – have not been predicted.

    “It could change the dimensions of the heliosphere, it could change its shape,” says Provornikova. “It could have different temperatures, different magnetic fields, different ionisation and all these different parameters. It’s very exciting because it’s an area of many discoveries, and we know so little about this interaction between our star and the local galaxy.”

    Whatever happens, two car-sized assortments of metal bolted to small parabolic dishes – the intrepid Voyager probes – will be our Solar System’s vanguard, revealing ever more about this strange and uncharted territory as we plough onwards through space.

    See the full article here .


    Please help promote STEM in your local schools.

    Stem Education Coalition

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