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  • richardmitnick 9:17 am on February 16, 2018 Permalink | Reply
    Tags: , , , , Solar Activity   

    From ESA: “Swarm details energetic coupling” 

    ESA Space For Europe Banner

    European Space Agency

    15 February 2018

    ESA/Swarm

    The Sun bathes our planet in the light and heat it needs to sustain life, but it also bombards us with dangerous charged particles in solar wind. Our magnetic field largely shields from this onslaught, but like many a relationship, it’s somewhat complicated. Thanks to ESA’s Swarm mission the nature of this Earth–Sun coupling has been revealed in more detail than ever before.

    Earth’s magnetic field is like a huge bubble, protecting us from cosmic radiation and charged particles carried by powerful winds that escape the Sun’s gravitational pull and sweep across the Solar System.

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

    The trio of Swarm satellites were launched in 2013 to improve our understanding of how the field is generated and how it protects us from this barrage of charged particles.

    Since our magnetic field is generated mainly by an ocean of liquid iron that makes up the planet’s outer core, it resembles a bar magnet with field lines emerging from near the poles.

    The field is highly conductive and carries charged particles that flow along these field lines, giving rise to field-aligned currents.

    Carrying up to 1 TW of electrical power – about six times the amount of energy produced every year by wind turbines in Europe – these currents are the dominant form of energy transfer between the magnetosphere and ionosphere.

    The shimmering green and purple light displays of the auroras in the skies above the polar regions are a visible manifestation of energy and particles travelling along magnetic field lines.

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    Aurora borealis
    Released 21/04/2017
    Copyright Sherwin Calaluan
    The aurora borealis is a visible display of electrically charged atomic particles from the Sun interacting with Earth’s magnetic field.

    The theory about the exchange and momentum between solar wind and our magnetic field actually goes back more than 100 years, and more recently the Active Magnetosphere and Planetary Electrodynamics Response Experiment satellite network has allowed scientists to study large-scale field-aligned currents.

    However, the Swarm mission is leading to exciting new wave of discoveries. A new paper [Journal of Geophysical Research] explores the dynamics of this energetic coupling across different spatial scales – and finds that it’s all in the detail.

    Ryan McGranaghan from NASA’s Jet Propulsion Laboratory said, “We have a good understanding of how these currents exchange energy between the ionosphere and the magnetosphere at large scales so we assumed that smaller-scale currents behaved in the same way, but carried proportionally less energy.”

    “Swarm has allowed us to effectively zoom in on these smaller currents and we see that, under certain conditions, this is not the case.

    ______________________________________________________________________________________________
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    Solar corona viewed by Proba-2
    Released 16/03/2015
    Copyright ESA/ROB
    This snapshot of our constantly changing Sun catches looping filaments and energetic eruptions on their outward journey from our star’s turbulent surface.

    The disc of our star is a rippling mass of bright, hot active areas, interspersed with dark, cool snaking filaments that wrap around the star. Surrounding the tumultuous solar surface is the chaotic corona, a rarified atmosphere of super-heated plasma that blankets the Sun and extends out into space for millions of kilometres.

    This coronal plasma reaches temperatures of several million degrees in some regions – significantly hotter than the surface of the Sun, which reaches comparatively paltry temperatures of around 6000ºC – and glows in ultraviolet and extreme-ultraviolet light owing to its extremely high temperature. By picking one particular wavelength, ESA’s Proba-2 SWAP (Sun Watcher with APS detector and Image Processing) camera is able to single out structures with temperatures of around a million degrees.

    ESA Proba 2

    As seen in the above image, taken on 25 July 2014, the hot plasma forms large loops and fan-shaped structures, both of which are kept in check by the Sun’s intense magnetic field. While some of these loops stay close to the surface of the Sun, some can stretch far out into space, eventually being swept up into the solar wind – an outpouring of energetic particles that constantly streams out into the Solar System and flows past the planets, including Earth.

    Even loops that initially appear to be quite docile can become tightly wrapped and tangled over time, storing energy until they eventually snap and throw off intense flares and eruptions known as coronal mass ejections. These eruptions, made up of massive amounts of gas embedded in magnetic field lines, can be dangerous to satellites, interfere with communication equipment and damage vital infrastructure on Earth.

    Despite the Sun being the most important star in our sky, much is still unknown about its behaviour. Studying its corona in detail could help us to understand the internal workings of the Sun, the erratic motions of its outer layers, and the highly energetic bursts of material that it throws off into space.

    Two new ESA missions will soon contribute to this field of study: Solar Orbiter is designed to study the solar wind and region of space dominated by the Sun and also to closely observe the star’s polar regions, and the Proba-3 mission will study the Sun’s faint corona closer to the solar rim than has ever before been achieved.

    NASA/ESA Solar Orbiter

    ESA Proba 3

    ______________________________________________________________________________________________

    “Our findings show that these smaller currents carry significant energy and that their relationship with the larger currents is very complex. Moreover, large and small currents affect the magnetosphere–ionosphere differently.”

    Colin Forsyth from University College London noted, “Since electric currents around Earth can interfere with navigation and telecommunication systems, this is an important discovery.

    “It also gives us a greater understanding of how the Sun and Earth are linked and how this coupling can ultimately add energy to our atmosphere.

    “This new knowledge can be used to improve models so that we can better understand, and therefore, ultimately, prepare for the potential consequences of solar storms.”

    ESA’s Swarm mission manager, Rune Floberghagen, added, “Since the beginning of the mission we have carried out projects to address the energy exchange between the magnetosphere, ionosphere and the thermosphere.

    “But what we are witnessing now is nothing short of a complete overhaul of the understanding of how Earth responds to and interacts with output from the Sun.

    “In fact, this scientific investigation is becoming a fundamental pillar for the extended Swarm mission, precisely because it is breaking new ground and at the same time has strong societal relevance. We now wish to explore this potential of Swarm to the fullest.”

    See the full article here .

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    The European Space Agency (ESA), established in 1975, is an intergovernmental organization dedicated to the exploration of space, currently with 19 member states. Headquartered in Paris, ESA has a staff of more than 2,000. ESA’s space flight program includes human spaceflight, mainly through the participation in the International Space Station program, the launch and operations of unmanned exploration missions to other planets and the Moon, Earth observation, science, telecommunication as well as maintaining a major spaceport, the Guiana Space Centre at Kourou, French Guiana, and designing launch vehicles. ESA science missions are based at ESTEC in Noordwijk, Netherlands, Earth Observation missions at ESRIN in Frascati, Italy, ESA Mission Control (ESOC) is in Darmstadt, Germany, the European Astronaut Centre (EAC) that trains astronauts for future missions is situated in Cologne, Germany, and the European Space Astronomy Centre is located in Villanueva de la Cañada, Spain.

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  • richardmitnick 12:17 pm on August 21, 2017 Permalink | Reply
    Tags: , , , , , , Solar Activity,   

    From EarthSky: “Studying sun’s atmosphere on eclipse day” 

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    EarthSky

    August 17, 2017
    EarthSky Voices

    Monday’s total solar eclipse will give scientists a rare opportunity to study the lower regions of the sun’s corona. Here’s what NASA scientists will be investigating.

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    A total solar eclipse gives scientists a rare opportunity to study the lower regions of the sun’s corona. These observations can help us understand solar activity, as well as the unexpectedly high temperatures in the corona. Image via NASA/S. Habbal, M. Druckmüller and P. Aniol.

    By Sarah Frazier, NASA’s Goddard Space Flight Center

    A total solar eclipse happens somewhere on Earth about once every 18 months. But because Earth’s surface is mostly ocean, most eclipses are visible over land for only a short time, if at all. The total solar eclipse of August 21, 2017, is different – its path stretches over land for nearly 90 minutes, giving scientists an unprecedented opportunity to make scientific measurements from the ground.

    Total solar eclipse of August 21, 2017: All you need to know

    When the moon moves in front of the sun on August 21, it will completely obscure the sun’s bright face. This happens because of a celestial coincidence – though the sun is about 400 times wider than the moon, the moon on August 21 will be about 400 times closer to us, making their apparent size in the sky almost equal. In fact, the moon will appear slightly larger than the sun to us, allowing it to totally obscure the sun for more than two and a half minutes in some locations. If they had the exact same apparent size, the total eclipse would only last for an instant.

    The eclipse will reveal the sun’s outer atmosphere, called the corona, which is otherwise too dim to see next to the bright sun. Though we study the corona from space with instruments called coronagraphs – which create artificial eclipses by using a metal disk to block out the sun’s face – there are still some lower regions of the sun’s atmosphere that are only visible during total solar eclipses. Because of a property of light called diffraction, the disk of a coronagraph must block out both the sun’s surface and a large part of the corona in order to get crisp pictures. But because the moon is so far away from Earth – about 230,000 miles away during the eclipse – diffraction isn’t an issue, and scientists are able to measure the lower corona in fine detail.

    NASA is taking advantage of the August 21, 2017, eclipse by funding 11 ground-based science investigations across the United States. Six of these focus on the sun’s corona.

    The source of space weather

    Our sun is an active star that constantly releases a flow of charged particles and magnetic fields known as the solar wind. This solar wind, along with discrete burps of solar material known as coronal mass ejections, can influence Earth’s magnetic field, send particles raining down into our atmosphere, and – when intense – impact satellites. Though we’re able to track these solar eruptions when they leave the sun, the key to predicting when they’ll happen could lie in studying their origins in the magnetic energy stored in the lower corona.

    A team led by Philip Judge of the High Altitude Observatory in Boulder, Colorado, will use new instruments to study the magnetic field structure of the corona by imaging this atmospheric layer during the eclipse. The instruments will image the corona to see fingerprints left by the magnetic field in visible and near-infrared wavelengths from a mountaintop near Casper, Wyoming. One instrument, POLARCAM, uses new technology based on the eyes of the mantis shrimp to obtain novel polarization measurements, and will serve as a proof-of-concept for use in future space missions. The research will enhance our understanding of how the sun generates space weather. Judge said:

    “We want to compare between the infrared data we’re capturing and the ultraviolet data recorded by NASA’s Solar Dynamics Observatory and JAXA/NASA’s Hinode satellite.

    NASA/SDO

    JAXA/HINODE spacecraft

    This work will confirm or refute our understanding of how light across the entire spectrum forms in the corona, perhaps helping to resolve some nagging disagreements.”

    The results from the camera will complement data from an airborne study imaging the corona in the infrared, as well as another ground-based infrared study led by Paul Bryans at the High Altitude Observatory.

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    High Altitude Observatory. Hawaii location.

    Bryans and his team will sit inside a trailer atop Casper Mountain in Wyoming, and point a specialized instrument at the eclipse. The instrument is a spectrometer, which collects light from the sun and separates each wavelength of light, measuring their intensity. This particular spectrometer, called the NCAR Airborne Interferometer, will, for the first time, survey infrared light emitted by the solar corona. Bryant said:

    “These studies are complementary. We will have the spectral information, which reveals the component wavelengths of light. And Philip Judge’s team will have the spatial resolution to tell where certain features are coming from.”

    This novel data will help scientists characterize the corona’s complex magnetic field — crucial information for understanding and eventually helping to forecast space weather events. The scientists will augment their study by analyzing their results alongside corresponding space-based observations from other instruments aboard NASA’s Solar Dynamics Observatory and the joint NASA/JAXA Hinode.

    In Madras, Oregon, a team of NASA scientists led by Nat Gopalswamy at NASA’s Goddard Space Flight Center in Greenbelt, Maryland, will point a new, specialized polarization camera at the sun’s faint outer atmosphere, the corona, taking several-second exposures at four selected wavelengths in just over two minutes. Their images will capture data on the temperature and speed of solar material in the corona. Currently these measurements can only be obtained from Earth-based observations during a total solar eclipse.

    To study the corona at times and locations outside a total eclipse, scientists use coronagraphs, which mimic eclipses by using solid disks to block the sun’s face much the way the moon’s shadow does. Typical coronagraphs use a polarizer filter in a mechanism that turns through three angles, one after the other, for each wavelength filter. The new camera is designed to eliminate this clunky, time-consuming process, by incorporating thousands of tiny polarization filters to read light polarized in different directions simultaneously. Testing this instrument is a crucial step toward improving coronagraphs and ultimately, our understanding of the corona — the very root of the solar radiation that fills up Earth’s space environment.

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    NASA’s Solar and Heliospheric Observatory, or SOHO, constantly observes the outer regions of the sun’s corona. During the Aug. 21, 2017, eclipse, scientists will observe the lower regions of the sun’s corona to better understand the source of solar explosions called coronal mass ejections, as well as the unexpectedly high temperatures in the corona. Image via ESA/NASA/SOHO.

    ESA/NASA SOHO

    Unexplained coronal heating

    The answer to another mystery also lies in the lower corona: It is thought to hold the secrets to a longstanding question of how the solar atmosphere reaches such unexpectedly high temperatures. The sun’s corona is much hotter than its surface, which is counterintuitive, as the sun’s energy is generated by nuclear fusion at its core. Usually temperatures go down consistently as you move away from that heat source, the same way that it gets cooler as you move away from a fire – but not so in the case of the sun’s atmosphere. Scientists suspect that detailed measurements of the way particles move in the lower corona could help them uncover the mechanism that produces this enormous heating.

    Padma Yanamandra-Fisher of the Space Science Institute will lead an experiment to take images of the lower corona in polarized light. Polarized light is when all the light waves are oriented the same way, and it is produced when ordinary, unpolarized light passes through a medium – in this case, the electrons of the inner solar corona. Yanamandra-Fisher said:

    “By measuring the polarized brightness of the inner solar corona and using numerical modeling, we can extract the number of electrons along the line of sight. Essentially, we’re mapping the distribution of free electrons in the inner solar corona.”

    Mapping the inner corona in polarized light to reveal the density of elections is a critical factor in modeling coronal waves, one possible source of coronal heating. Along with unpolarized light images collected by the NASA-funded citizen science project called Citizen CATE, which will gather eclipse imagery from across the country, these polarized light measurements could help scientists address the question of the solar corona’s unusually high temperatures.

    Shadia Habbal of the University of Hawaii’s Institute for Astronomy in Honolulu will lead a team of scientists to image the sun during the total solar eclipse. The eclipse’s long path over land allows the team to image the sun from five sites across four different states, about 600 miles apart, allowing them to track short-term changes in the corona and increasing the odds of good weather.

    They will use spectrometers, which analyze the light emitted from different ionized elements in the corona. The scientists will also use unique filters to selectively image the corona in certain colors, which allows them to directly probe into the physics of the sun’s outer atmosphere.

    With this data, they can explore the composition and temperature of the corona, and measure the speed of particles flowing out from the sun. Different colors correspond to different elements — nickel, iron and argon — that have lost electrons, or been ionized, in the corona’s extreme heat, and each element ionizes at a specific temperature. By analyzing such information together, the scientists hope to better understand the processes that heat the corona.

    Amir Caspi of the Southwest Research Institute in Boulder, Colorado, and his team will use two of NASA’s WB-57F research jets take observations from twin telescopes mounted on the noses of the planes. They will ­­­­­capture the clearest images of the sun’s outer atmosphere — the corona — to date and the first-ever thermal images of Mercury, revealing how temperature varies across the planet’s surface.

    Bottom line: NASA scientists will study the sun’s atmosphere at the total solar eclipse of August 21, 2017. [Alot!!]

    See the full article here .

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  • richardmitnick 4:16 pm on February 28, 2017 Permalink | Reply
    Tags: GOES-16 SUVI instrument, , , NOAA’s GOES-16 satellite, Solar Activity   

    From NOAA and Goddard: “First Solar Images from NOAA’s GOES-16 Satellite” 

    NASA Goddard Banner
    NASA Goddard Space Flight Center

    1

    NOAA

    Feb. 27, 2017

    Michelle Smith
    National Oceanic and Atmospheric Administration, Silver Spring, Md.
    michelle.smith@nasa.gov

    Rob Gutro
    NASA’s Goddard Space Flight Center, Greenbelt, Md.
    Robert.j.gutro@nasa.gov

    The first images from the Solar Ultraviolet Imager or SUVI instrument aboard NOAA’s GOES-16 satellite have been successful, capturing a large coronal hole on Jan. 29, 2017.

    NOAA GOES-16
    NOAA GOES-16

    The sun’s 11-year activity cycle is currently approaching solar minimum, and during this time powerful solar flares become scarce and coronal holes become the primary space weather phenomena – this one in particular initiated aurora throughout the polar regions. Coronal holes are areas where the sun’s corona appears darker because the plasma has high-speed streams open to interplanetary space, resulting in a cooler and lower-density area as compared to its surroundings.


    Access mp4 video here .
    This animation from January 29, 2017, shows a large coronal hole in the sun’s southern hemisphere from the Solar Ultraviolet Imager (SUVI) on board NOAA’s new GOES-16 satellite. SUVI observations of solar flares and solar eruptions will provide an early warning of possible impacts to Earth’s space environment and enable better forecasting of potentially disruptive events on the ground. This animation captures the sun in the 304 Å wavelength, which observes plasma in the sun’s atmosphere up to a temperature of about 50,000 degrees. When combined with the five other wavelengths from SUVI, observations such as these give solar physicists and space weather forecasters a complete picture of the conditions on the sun that drive space weather. Credits: NOAA/NASA

    SUVI is a telescope that monitors the sun in the extreme ultraviolet wavelength range. SUVI will capture full-disk solar images around-the-clock and will be able to see more of the environment around the sun than earlier NOAA geostationary satellites.

    The sun’s upper atmosphere, or solar corona, consists of extremely hot plasma, an ionized gas. This plasma interacts with the sun’s powerful magnetic field, generating bright loops of material that can be heated to millions of degrees. Outside hot coronal loops, there are cool, dark regions called filaments, which can erupt and become a key source of space weather when the sun is active. Other dark regions are called coronal holes, which occur where the sun’s magnetic field allows plasma to stream away from the sun at high speed. The effects linked to coronal holes are generally milder than those of coronal mass ejections, but when the outflow of solar particles is intense – can pose risks to satellites in Earth orbit.

    The solar corona is so hot that it is best observed with X-ray and extreme-ultraviolet (EUV) cameras. Various elements emit light at specific EUV and X-ray wavelengths depending on their temperature, so by observing in several different wavelengths, a picture of the complete temperature structure of the corona can be made. The GOES-16 SUVI observes the sun in six EUV channels.

    Data from SUVI will provide an estimation of coronal plasma temperatures and emission measurements which are important to space weather forecasting. SUVI is essential to understanding active areas on the sun, solar flares and eruptions that may lead to coronal mass ejections which may impact Earth. Depending on the magnitude of a particular eruption, a geomagnetic storm can result that is powerful enough to disturb Earth’s magnetic field. Such an event may impact power grids by tripping circuit breakers, disrupt communication and satellite data collection by causing short-wave radio interference and damage orbiting satellites and their electronics. SUVI will allow the NOAA Space Weather Prediction Center to provide early space weather warnings to electric power companies, telecommunication providers and satellite operators.

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    These images of the sun were captured at the same time on January 29, 2017 by the six channels on the SUVI instrument on board GOES-16 and show a large coronal hole in the sun’s southern hemisphere. Each channel observes the sun at a different wavelength, allowing scientists to detect a wide range of solar phenomena important for space weather forecasting.
    Credits: NOAA

    SUVI replaces the GOES Solar X-ray Imager (SXI) instrument in previous GOES satellites and represents a change in both spectral coverage and spatial resolution over SXI.

    NASA successfully launched GOES-R at 6:42 p.m. EST on Nov. 19, 2016, from Cape Canaveral Air Force Station in Florida and it was renamed GOES-16 when it achieved orbit. GOES-16 is now observing the planet from an equatorial view approximately 22,300 miles above the surface of Earth.

    NOAA’s satellites are the backbone of its life-saving weather forecasts. GOES-16 will build upon and extend the more than 40-year legacy of satellite observations from NOAA that the American public has come to rely upon.

    For more information about GOES-16, visit: http://www.goes-r.gov/ or http://www.nasa.gov/goes

    To learn more about the GOES-16 SUVI instrument, visit:

    http://www.goes-r.gov/spacesegment/suvi.html

    See the full article here.

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    NASA’s Goddard Space Flight Center is home to the nation’s largest organization of combined scientists, engineers and technologists that build spacecraft, instruments and new technology to study the Earth, the sun, our solar system, and the universe.

    Named for American rocketry pioneer Dr. Robert H. Goddard, the center was established in 1959 as NASA’s first space flight complex. Goddard and its several facilities are critical in carrying out NASA’s missions of space exploration and scientific discovery.

    NASA Goddard Campus
    NASA/Goddard Campus
    NASA

     
  • richardmitnick 8:43 am on October 8, 2016 Permalink | Reply
    Tags: , , , Solar Activity, We might have finally figured out the mysterious force that controls the Sun's magnetic field   

    From Science Alert: “We might have finally figured out the mysterious force that controls the Sun’s magnetic field” 

    ScienceAlert

    Science Alert

    7 OCT 2016
    FIONA MACDONALD

    What’s influencing our Sun?

    1
    ESA & NASA

    Our Sun is a beautiful, bubbling mess of plasma that’s controlled by its magnetic field – and roughly once every 11 years, the polarity of that magnetic field is reversed, causing a spike in Sun spots and solar flares.

    It’s beautiful and predictable, but also baffling. What controls the magnetic field? And what causes those regular fluctuations? It’s something that’s puzzled scientists for decades, but a group of researchers have just put forward a possible new explanation: maybe it’s us.

    Well, not just us, but Earth, Venus, and Jupiter combined. The researchers came up with the idea because not only does the Sun’s magnetic field flip every 11 years, every 11.07 years, the Sun, Earth, Venus, and Jupiter are all aligned.

    “We asked ourselves: is it a coincidence that the solar cycle corresponds with the cycle of the conjunction or the opposition of the three planets?” said one of the physicists, Frank Stefani, from Helmholtz-Zentrum Dresden-Rossendorf in Germany.

    That question isn’t new, and researchers have noticed the link between the planetary alignment and the Sun’s magnetic field before, but they haven’t been able to figure out how the very weak tidal effects of three planets could influence the Sun’s dynamo.

    But with new calculations into the behaviour of the solar magnetic field, the team has found evidence to suggest that, thanks to the principle of resonance – the build up of an effect – the planets could actually be having a profound effect on the Sun.

    Here’s what we know so far.

    The Sun’s dynamo magnetic field is controlled by a combination of two effects: the omega effect and the alpha effect. The omega effect is understood to originate in the tachocline – the narrow band between the Sun’s inner radiative zone and the outer areas.

    In the tachocline, lots of different rotating areas converge, and researchers suspect that this generates two magnetic belts situated north and south of the solar equator.

    But the alpha effect is more mysterious. The alpha effect is what creates the poloidal field – one that circles from pole to pole – and a leading hypothesis suggests that it originates near sunspots on the Sun’s surface. But this has never quite explained the 11-year cycle.

    The German team has an alternate hypothesis – their calculations show that the alpha effect is prone to oscillations under certain conditions, and these oscillations could be triggered by the alignment of the three planets, before growing into something more powerful.

    “The impulse for this alpha-oscillation requires almost no energy,” said Stefani. “The planetary tides could act as sufficient pace setters for this.”

    This oscillation of the alpha effect, also known as the Tayler instability, then builds up to become powerful enough to flip the polarity of the magnetic field, thanks to resonance. “If you only just give a swing small pushes, it will swing higher with time,” Stefani explains, referring to resonance.

    To back up their hypothesis, the team discovered the first evidence that the Tayler instability is also oscillating back and forth between right- and left-handedness with very little energy, which suggests that the planetary alignment has a strong enough effect to flip it.

    “Our calculations show that planetary tidal forces act here as minute external pace setters,” said Stefani.

    “The oscillation in the alpha effect, which is triggered approximately every 11 years, could cause the polarity reversal of the solar magnetic field and, ultimately, dictate the 22-year cycle of the solar dynamo.”

    More research is needed before we can say for sure whether the effect of three planets could be influencing our Sun, but it’s an interesting hypothesis worthy of further investigation. And it would be pretty cool to think that our little globe could have an effect on something so massive.

    The research has been published in Solar Physics.

    See the full article here .

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  • richardmitnick 11:18 am on August 31, 2016 Permalink | Reply
    Tags: , , , Monitoring Holes in the Sun’s Corona, , Solar Activity   

    From AAS NOVA: “Monitoring Holes in the Sun’s Corona” 

    AASNOVA

    American Astronomical Society

    31 August 2016
    Susanna Kohler

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    A view of a hole in the Sun’s corona from the Solar Dynamics Observatory. A new study tracks the trend of coronal holes from 1975 to 2014. [NASA/SDO/helioviewer]

    NASA/SDO
    NASA/SDO

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    Coronal holes form where magnetic field lines open into space (B) instead of looping back to the solar surface (A). [Sebman81]

    Source of the Fast Solar Wind

    As a part of the Sun’s natural activity cycle, extremely low-density regions sometimes form in the solar corona. These “coronal holes” manifest themselves as dark patches in X-ray and extreme ultraviolet imaging, since the corona is much hotter than the solar surface that peeks through from underneath it.

    Coronal holes form when magnetic field lines open into space instead of looping back to the solar surface. In these regions, the solar atmosphere escapes via these field lines, rapidly streaming away from the Sun’s surface in what’s known as the “fast solar wind”.

    Coronal Holes Over Space and Time

    Automated detection of coronal holes from image-based analysis is notoriously difficult. Recently, a team of scientists led by Ken’ichi Fujiki (ISEE, Nagoya University, Japan) has developed an automated prediction technique for coronal holes that relies instead on magnetic-field data for the Sun, obtained at the National Solar Observatory’s Kitt Peak between 1975 and 2014. The team used these data to produce a database of 3335 coronal hole predictions over nearly 40 years.

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    Latitude distribution of 2870 coronal holes (each marked by an x; color indicates polarity), overlaid on the magnetic butterfly map of the Sun. The low-latitude coronal holes display a similar butterfly pattern, in which they move closer to the equator over the course of the solar cycle. Polar coronal holes are more frequent during solar minima. [Fujiki et al. 2016]

    Examining trends in the coronal holes’ distribution in latitude and time, Fujiki and collaborators find a strong correlation between the total area covered by low-latitude coronal holes (holes closer to the Sun’s equator) and sunspot activity. In contrast, the total area of high-latitude coronal holes (those near the Sun’s poles) peaks around the minimum in each solar cycle and shrinks around each solar maximum.

    Predicting the Impact of the Solar Wind

    Why do these observations matter? Coronal holes are the source of the fast solar wind, so if we can better predict the frequency and locations of coronal holes in the future, we can make better predictions about how the solar wind might impact us here on Earth.

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    Periodicity of high-latitude (orange) and low-latitude (blue) coronal-hole areas, and periodicity of galactic cosmic rays detected at Earth (black). The cosmic rays track the polar coronal-hole area behavior with a 1-year time lag. [Fujiki et al. 2016]

    In one example of this, Fujiki and collaborators show that there’s a distinct correlation between polar coronal-hole area and observed galactic cosmic rays. Cosmic rays from within our galaxy have long been known to exhibit a 22-year periodicity. Fujiki and collaborators show that the periodicity of the galactic cosmic-ray activity tracks that of the polar coronal-hole area, with a ~1-year lag time — which is equivalent to the propagation time of the solar wind to the termination shock.

    Polar coronal holes are therefore a useful observable indicator of the dipole component of the solar magnetic field, which modulates the incoming cosmic rays entering our solar system. This coronal hole database will be a useful tool for understanding the source of solar wind and the many ways the wind influences the Earth and our solar system.

    Citation

    K. Fujiki et al 2016 ApJ 827 L41. doi:10.3847/2041-8205/827/2/L41

    See the full article here .

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  • richardmitnick 10:21 am on May 29, 2016 Permalink | Reply
    Tags: , , , Solar Activity, There's a Giant Coronal Hole In the Sun Right Now   

    From CosmosUp: “There’s a Giant Coronal Hole In the Sun Right Now” 

    CosmosUp bloc

    CosmosUp

    29, May 2016

    This week, NASA’ Solar Dynamics Observatory (SDO) captured a remarkable phenomenon on the sun’s surface, a giant hole known as coronal hole taking up more than 10% of our sun’s surface.

    NASA/SDO
    NASA/SDO

    From here, our sun seems eerily calm but it is actually a red-hot ball of violence capable of spewing powerful blasts of radioactive particles towards Earth.

    These powerful blast could be extremely dangerous, messing up with our communication systems and satellites and would be dangerous to unshielded astronauts, large doses could be even fatal; thankfully, Earth’s magnetosphere is there to keep us safe — these blast cannot harm our human bodies as long as we remain on the surface of Earth.

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

    So, what causes these violent streams? The solar wind emanates from the Sun in all directions, but one of the sun’ lesser-known weather phenomena, called coronal holes, emanate most readily these stream of particles.

    Coronal holes are low-density regions of the sun’s atmosphere known as the corona – the aura of plasma surrounding the sun,

    explained NASA scientists.

    Because they contain little solar material, they have lower temperatures and thus appear much darker than their surroundings. Coronal holes are visible in certain types of extreme ultraviolet light, which is typically invisible to our eyes, but is colorized here in purple for easy viewing.
    Such phenomenon are being investigated by NASA’ Solar Dynamics Observatory, a spacecraft launched on February 11, 2010, that scientists use to understand the causes of solar variability and its impacts on Earth.

    From May 17-19, SDO spotted a colossal coronal hole covering the northern hemisphere of our star, so huge that scientists aren’t quite sure how to explain it, but it is clear that the sun is going through something very strange; this is the first time such a massive hole has been found or at least captured on the video, let’s take a look:

    1
    In this image, you can see something very unusual is happening with our sun, something that we have yet to fully understand; usually holes have been seen but nothing at the size of the whole recently found.

    Though NASA says the recent holes in our sun, even the large ones like this one, is actually not of great concern, it is totally normal but some researchers said that something is clearly happens with our sun, such large hole have never seen before.

    So, guys what do you think? Is our sun is going dark? Or NASA is telling us the truth and we have nothing to worry about?

    2

    See the full article here .

    Please help promote STEM in your local schools.

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    Stem Education Coalition

     
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