WHY ARE WE SO AFRAID OF THE SUN?
MAYBE WE KNOW A LITTLE TOO MUCH OF WHAT IT'S
BUT NOT ENOUGH OF THE RIGHT INFORMATION?
SEE: THE SUN'S MAGNETIC FIELD FLIPS OVER - 3-4-2001
Explanation: Our Sun is still very active. In the year 2000, our Sun went though Solar Maximum, the time in its 11-year cycle where the most sunspots and explosive activities occur. Sunspots, the Solar Cycle, and solar prominences are all caused by the Sun's changing magnetic field. Pictured above is a solar prominence that erupted in 2002 July, throwing electrons and ions out into the Solar System. The above image was taken in the ultraviolet light emitted by a specific type of ionized helium, a common element on the Sun. Particularly hot areas appear in white, while relatively cool areas appear in red. Our Sun should gradually quiet down until Solar Minimum occurs, and the Sun is most quiet. No one can precisely predict when Solar Minimum will occur, although some signs indicate that it has started already!
TAKEN FROM: http://www.bushcountry.org/
The central body of our Solar System, the Sun is an average sized star of the YELLOW DWARF variety that formed roughly 4.6 BILLION years ago at the center of an enormous swirling gas cloud that became the Solar System.
The concentration of pressure at the center of this swirling cloud of (mostly) hydrogen triggered a nuclear fusion reaction and the star we know as the Sun was born. In this fusion reaction, typical of all stars, four nuclei of hydrogen atoms (the simplest element), fused to form a single helium (the second simplest element) having two protons) nuclei. The resulting reaction released a tremendous amount of energy.
It is theorized that in about 5 BILLION YEARS, as its hydrogen becomes depleted, the Sun will expand from its present status of yellow dwarf star to become a red giant, with a diameter greater than the orbit of Venus. According to this generally accepted theory, the Sun will then collapse back to a white dwarf type star (smaller than its present size) and gradually become a burnt ember which would then be ironically referred to as a black dwarf.
The gravitational force of the Sun literally defines the Solar System and controls the orbital paths of the other bodies within it. The Sun is also the source of most of the heat in the Solar System and thus it provides the warmth that makes life possible on at least one of the bodies in the Solar System.
The temperature of the Sun is estimated at roughly 20 million degrees centigrade, and the Sun's surface temperature averages 11,000 degrees Fahrenheit or approximately 6000 degrees Kelvin.
The energy radiated from the Sun is called solar radiation, which (as measured in wavelengths from the longest to the shortest) can be simplified as including:
(a) radio waves
(c) infrared radiation (perceived on earth as heat)
(d) the visible light spectrum
(e) ultraviolet radiation
(g) gamma rays
So powerful is solar radiation that its ultra-violet wavelengths can burn (or tan) human skin on Earth, and direct light from the visible spectrum can do permanent damage to the human eye.
The sun, being a gaseous sphere, has no solid surface, nor could any molecular solid exist at such incredible temperatures. The Sun does, however, have a nearly opaque surface. . . a sea of gaseous firestorms known as the photosphere.
The firestorms that comprise the photosphere are roughly 600 miles in diameter and appear as granules in the vastness of the Sun. Their apparent opacity is due to the presence of negative hydrogen ions. During the approximate eight-minute lifespan of the granule, hot gas rises out of the center, pushing cooler gases aside and into the arrow darker and cooler spaces between granules. Amid the typical granules, there are 'supergranules' with diameters of up to 18,000 miles and lifespans of up to 24 hours.
Other 'surface features' on the photosphere are 'solar flares' and 'sunspots'. Solar flares are violent surface eruptions that explode from the photosphere with the energy of 10 million hydrogen bombs, sending forth a stream of solar radiation that can disrupt radio signals on the Earth.
It may take several hours or even days for an individual flare to build up, but the actual flare happens in a matter of minutes when the energy is released. The resulting shockwaves travel outward across the photosphere and up into the chromosphere and corona for hundreds of thousands of miles at speeds on the order of three million mph.
The study of solar flares and particles released is necessary not only because of its effect on the Earth but because of the negative effect on spacecraft and astronauts beyond Earth's atmosphere. The charged particles released in the flares are attracted by the Earth's magnetic field and spiral in at the north and south magnetic poles, causing the Aurora Borealis in the Earth's atmosphere.
Sunspots were first discovered by the Chinese 2,000 years ago and were first studied systematically by Italian astronomer Galileo (1564-1642) in the seventeenth century. It was his discovery that led our knowledge of the sun's rotation and that there is a 11 year cycle that seems to have an effect on the weather on Earth. When there are fewer sun spots on the sun, the Earth's weather is colder. Sunspots vary in size and shape, and can be up to 40,000 miles across. It takes a week to 10 days for a sun spot to develop and about two weeks to decay They usually occur in groups.
DATA FOR THE SUN
Taken from: 'The Atlas of the Solar System' by Bill Yenne (1990)
|Diameter = 870,331.25 miles
|Mass = 4.3959 x 10 30 lb (1.9891 x 10 30 kg)|
of equator = 26.8 Earth Days
of latitude 30 degrees: 28.2 Earth days
|at latitude 50 degrees: 30.8 Earth Days||of latitude 75 degrees: 31.8 Earth days|
|Surface Temperature: 10,430 degrees F||Interior temperature: 26,999,540 degrees F|
|Major photosphere components|
|Hydrogen (73.46%)||Neon (.12%)|
|Helium (24.85%)||Nitrogen (.09%)|
|Oxygen (.77%)||Silicon (.07%)|
|Carbon (.29%)||Magnesium (.05%)|
|Iron (.16%)||Sulphur (.04%)|
Another source, The Hawaian Astronomical Society gives the percentages thus:
Above the photosphere there is a thinner, more visually transparent layer known as the chromosphere. This layer cannot be measured exactly, but about 6,000 miles thick. The common feature of this layer are 'spicules' which are long thin fingers of luminous gas which appear like a vast field of fiery grass growing up from the photosphere. They are evenly distributed all over the sun, but most prominently near sun spots.
'Fibrils' are horizontal wisps of gas that drift through the chromosphere. The are similar to spicules , but last about twice as long.
'Prominences' are gigantiic luminous plumes of gas that appear like tongues of flame. The leap up sometimes as far as 100,000 miles.
Beyond the chromosphere is the corona, a vast field of hydrogen particles that extends for millions of miles into space. The corona is so sparse, it is not visible against the glare of the Sun except during total eclipses. . . when the Moon gets between the Earth and the Sun. The corona is most prominent at the Sun's equator and there are holes in the polar regions, but when the sun is very active, the corona surrounds the entire Sun.
The mystery of the sun is that the corona is hotter than the photosphere. The law of thermodynamics holds that heat cannot be conducted from the cooler to the warmer. It has been suggested that it is the dynamics of the solar magnetic fields and acoustic energy may be the answer to the mystery.
The coronal flares which are called transients are blast waves, and are giant loops of corona material, that reach speeds of more than a million mph, and are released out into the Solar system. The Solar wind carries these transient energies to distances farther than the Earth's orbit. They have 10 times the energy as the flares which trigger them.
The Solar wind is constant and has gusts from 450,000 mph to 2 million mph, and continues out into space. The solar wind spirals out from the sun, rotating with the sun until it reaches a distance of approximately 100 million miles (roughly 1 AU). From that point it travels outward with less interference from the Sun's magnetic field.
About 3000 tons of subatomic particles are blown outward from the Sun in the solar wind every hour. At that rate, it would take about 200,000 BILLION years for the Sun's entire mass to be dissipated by the solar wind.
In 1998 there was a new discovery. Observers have noted what appear to be brief, localised bright patches within these supergranular patterns. These flashes, now known as blinkers, are small explosions in the Suns atmosphere, each of them about the size of the Earth. Although these blinkers appear to be rather insignificant since they are small and emit only one millionth the energy of a solar flare, they are distributed over the entire Sun and are visible for several minutes. They seem to be the visible representation of a transient process which is basic to the way the solar atmosphere works.
THE SOLAR AND HELIOSPHERIC OBSERVATORY
SOHO was launched on December 2, 1995, and placed in orbit around the Sun at a position between the Earth and Sun on February 14, 1996. Scientific operations began in April 1996. Since then, RAL's CDS instrument has been used by 36 institutes from 12 countries and has carried out 50,000 observations.
Excerpts from The Dark Side of the Solar Flare Myth -D. V. Reames
CMEs came late to the domain of known solar eruptive phenomena, where flares stood alone for over 100 years. CMEs can be massive objects; spanning 120° in solar latitude or longitude, they can involve 10^16 g of gas that is suddenly ejected at speeds up to 2000 km/s with a kinetic energy of >10^32 ergs, all directed outward into interplanetary space. Thousands of CMEs have now been observed by the Skylab, SMM, SOLWIND and Mauna Loa coronagraphs and the Helios photometers. Their properties and their relationship with flares have been extensively reviewed [Kahler 1992; Hundhausen 1995; Webb and Howard 1994; Webb 1995]. Flares are observed with no associated CMEs, and conversely; the two phenomena are not causally related. At solar maximum the magnetic equator of the Sun, called the streamer belt or heliospheric current sheet, is highly inclined to the ecliptic so it passes near the solar poles. At this time CMEs are distributed around the streamer belt at all heliographic latitudes while classical H-alpha flares only occur in a limited latitude band.
The motivation to distinguish flares and CMEs goes far beyond semantics. The term "flare" evokes the idea of limited spatial and temporal extent. We will see that this alone causes serious errors when flares and CMEs are not distinguished. Like others, I once believed that high-energy particles were only accelerated in point-source flares. Thus, I speak as former disciple (and victim) of the flare myth. "Flares" also imply chromospheric and coronal heating and are classically observed by photons from a hot gas. The 100-year history of flare observations has produced a significant photon bias that tends to discount interplanetary observations of plasma processes that are not visible in photons.
Interplanetary phenomena near Earth can provide information on their own solar origin. In some cases this information is internal; for example, ionization states of ions carry information on the temperature of the source plasma. More often it involves extensive comparisons between local phenomena and radio, X-ray, gamma-ray and CME observations in the related solar events. All interplanetary shocks energetic enough to be seen as type II radio bursts, for example, are found to have associated CMEs [Cane, Sheeley and Howard 1987]. The interplanetary properties of CMEs have been identified and their effect on the magnetosphere has been studied directly [see Gosling 1993]. Energetic particle observations identified two populations, clearly distinguished by their abundances, ionization states, and time and longitude distributions. One population comes from impulsive flares and the other, involving the largest, most energetic events, comes from CME-driven shocks [Reames 1990, 1993, 1994, 1995]. Gosling [1993, 1994] basically combined the published and generally-accepted results from a variety of interplanetary observations into "The flare myth." Most in the interplanetary community were well aware that CMEs, not flares, cause the dominant near-Earth phenomena of relevance to solar-terrestrial studies. Except for the "sudden ionospheric disturbances" caused directly by photons, flares are not "geo-effective."
In the case of CMEs, a quiescent prominence 300,000 km in length can become magnetically unstable and be launched like a giant helium balloon on time scales of tens of minutes to hours
One of the difficulties in the present controversy is that flares and CMEs often occur together. However, one does not cause the other. Even when flares and CMEs do occur together, there is little relationship between their positions or timing and often there is more energy in the CME than in the associated flare [Kahler 1992]. Kahler  coined the term "big flare syndrome" to point out that, despite appearances, not all processes occurring in conjunction with big flares are causally related to the flare or to each other, even when well correlated. Our greatest progress in establishing causal relationships has come from the observation of small impulsive flares without CMEs and from erupting-filament events which are CMEs without impulsive flares [Kahler 1992].
Flares last for hours, at most, but large SEP events last for days. Flares are also confined to a few degrees on the Sun but large SEP events (and interplanetary shocks) are seen over a span of ~180°, sometimes more. Only recently have we understood that the shocks from CMEs cross field lines to accelerate the particles locally over vast regions of space and for long intervals of time in the largest SEP events [see Reames 1993, 1994, 1995].
The importance of CME shocks in large SEP events is now generally recognized; yet the consequences of the old flare paradigm still linger. There are still attempts to derive diffusive interplanetary scattering parameters from particle time profiles without considering the moving, evolving shock source. 3He-rich events, with impulsive injection, tell us the ambient parallel scattering mean free path is long (~1 AU), yet in shocks it becomes quite short (~10^-3 AU) because of waves generated by the accelerated particles themselves. Neglect of this wave generation leads to the erroneous conclusion that shock acceleration is "too slow." As a CME comes out from the Sun to 1 AU, an observer's connection point to the shock swings through ~50° or more in longitude, sampling a large gradient in shock strength. Also, the speed at the nose of the shock can slow by a factor of ~2 or 3 between the Sun and the Earth. This evolution is largely ignored in the naive models we have inherited from the flare myth.
Distinguishing events as "impulsive flares" and "eruptive flares" does not end the confusion since the common perception of a "flare" is something that will easily fit in an active region. Some models of CMEs rising above "eruptive flares" begin with low-lying loops emerging from a flat solar surface. Such models do not describe real CMEs where pre-existing magnetic structures typically arch through angles of ~45° from one active region to another. These large structures are much less likely to lead to significant coronal or chromospheric heating in producing CMEs. These modelers are being misled by the flare myth just as others have been; they consider only initial conditions where flares are likely to accompany CMEs.
. Large SEP events have a 96% correlation with CMEs [Kahler et al. 1984] but a key piece of evidence for shock acceleration is the ionization state of elements such as Fe. Near 1 MeV/amu, QFe=14.1±0.2 [Luhn et al. 1985, 1987] indicates that the source plasma has a temperature ~2 MK, similar to the temperature of the corona and to the ionization states seen in the solar wind. The source cannot involve heated (>10 MK) plasma that exists in flares or reconnection sites. Only 3He-rich events show ionization states (e.g. QFe=20.5±1.2) compatible with a hot source. Recent measurements of Fe at 200-600 MeV/amu in large SEP events show ionization states [Tylka et al. 1995] in agreement with those of Luhn et al. . Ionization state measurements by 4 experiments on 3 different spacecraft now support the idea of shock acceleration of ambient, unheated coronal and solar-wind plasma.
Kahler  has studied the solar injection intensities of protons up to 25 GeV as a function of the altitude of the leading edge of the CME. The intensities reach maximum only after the CME is beyond ~10 solar radii, outside the corona. In the 1989 September 29 event the leading edge of the CME was observed [Kahler 1994] to have a speed of over 1800 km/s. This was also one of the events where Fe was observed to have coronal charge states at 200-600 MeV/amu. In this event the shock came across the high corona from a source behind the west limb to accelerate ambient protons to energies as high as 25 GeV and ambient Fe as high as 600 MeV/amu at the base of the field line connected to Earth. The relativistic Fe ions must be accelerated in the tenuous high corona beyond ~2 solar radii to avoid being stripped of their orbital electrons. "
D. V. Reames -NASA/ Goddard Space Flight Center, Greenbelt, MD
The SOHO Coronal Diagnostic Spectrometer
THE SOLAR WIND
There are two types of solar wind flow: quasi-stationary and transient (see, for example, the review by Neugebauer, 1991). There are at least two sources of quasi-stationary solar wind: fast flows from coronal holes (CH) and slow "interstream" (IS) flows, some or all of which originate in or near visible structures called coronal streamers. Coronal holes are regions of the solar corona with open or unipolar magnetic fields and anomalously low density which appear dark in x-ray images of the Sun. Coronal streamers, on the other hand, are bright, dense structures extending well out into the corona. The "quiet corona" between the holes and the streamers may also lead to slow, interstream flow; alternatively, the entire quasi-stationary solar wind may originate only in coronal holes and streamers whose flows expand laterally to fill all solar latitudes and longitudes.
Transient flows of the solar wind are produced by solar eruptions referred to as coronal mass ejections (CME). CMEs are associated with the disruption of closed magnetic field lines above the solar surface. Depending on the energy released in the eruption, the solar wind from a CME can have either low or high speed. The frequency of occurrence of CMEs varies in concert with the solar activity cycle.
Solar Wind Properties
SPACE WEATHER - EFFECT ON EARTH
The response of our space environment to the constantly changing Sun is known as "Space Weather". Most of the time space weather is of little concern in our everyday lives. However, when the space environment is disturbed by the variable outputs of the Sun, technologies that we depend on both in orbit and on the ground can be affected. Some of the most dramatic space weather effects occur in association with eruptions of material from the solar atmosphere into interplanetary space. Thus, our space weather is a consequence of the behavior of the Sun, the nature of Earth's magnetic field and atmosphere, and our location in the solar system.
The increasing deployment of radiation-, current-, and field-sensitive technological systems over the last few decades and the increasing presence of complex systems in space combine to make society more vulnerable to solar-terrestrial disturbances. This has been emphasized by the large number of problems associated with the severe magnetic storms between 1989 and 1991 as the 11-year solar activity cycle peaked.
We are now approaching a new solar maximum. The last solar minimum was reached sometime late 1996 and we have just started on cycle 23. An increasing number of active regions from the new cycle have started to appear and the number of flares and CMEs will continue to increase the next few years, as will the strength of the events.
One important issue for the next solar maximum is that our society is much more sensitive to space weather activity today compared to the last solar maximum in 1991. This could be a major concern for the coming solar maximum in 2000-2001.
WHAT CAN HAPPEN DURING SOLAR MAXIMUM?
The solar extreme ultraviolet (EUV) output is the primary factor contributing to the decay of satellite and space debris orbits due to frictional interaction with the upper atmosphere ("drag"). As the solar EUV emission increases with solar activity, its absorption heats the upper atmosphere and increases the densities of atoms and molecules at a satellite's altitude. Proxies such as the radio emission at 10.7 cm are currently used by satellite operators in commercial enterprises and national agencies to analyze and predict changes in the upper atmosphere and the resulting orbital evolution. These proxies have not proven very effective in making accurate predictions, owing to additional increases in satellite drag from flare and auroral zone heating of the atmosphere.
Orbital decay can cause loss of contact and special problems for space facilities such as the Hubble Space Telescope, which will require "boosts" to maintain altitude; it can also result in aborted missions. In addition, the ever-increasing collection of space debris1 that must be tracked can be redistributed by increased drag. Although understanding of the sources of solar EUV radiation has improved dramatically since the last solar maximum, the new models of EUV behavior are based on observations that have not been tested through a solar maximum, when the number and intensity of transient contributions greatly increase.2 The contribution of variable auroral zone heating to drag is similarly difficult to characterize. Meanwhile, the demand for information on satellite drag grows with each passing solar cycle, driven by the increased use of space-based communications and navigation systems and the necessity of long-term planning for spacecraft in low-altitude orbits.
Radio and Communications Interference
A solar maximum affects radio communications in several ways. Most directly, enhanced radio output from the Sun degrades the effective sensitivity of receiver systems linking to satellites near the Earth-Sun line. Historically, the dominant effect has been on long-range, short-wave communication, which depends on radio-wave reflection from the bottom of the ionosphere. Enhanced EUV and soft x-ray emissions change the electron density and gradients in the ionosphere, directly and profoundly affecting this reflection. The effects of enhanced irregularities that often accompany ionospheric disturbances are also of growing importance. The resulting increased scattering of satellite-to-ground ultrahigh-frequency (UHF) transmission, or scintillation, can seriously interfere with direct satellite communication links. Similarly, the variability in propagation conditions degrades the performance of global positioning system (GPS) receivers, very low frequency (VLF) communications systems, and over-the-horizon radars. These effects are of particular concern in the high-latitude regions of auroral activity, but they can also be severe in near-equatorial regions, where convective overturning and enhanced electron densities in the ionosphere can amplify the scintillations.
Satellite and Space Systems Hazards
Transient populations of energetic (MeV) protons, which enhance the Van Allen belt radiation for weeks to months following the arrival of a fast CME, potentially can affect the operation of spacecraft, including spacecraft in the highly populated geosynchronous orbit. For example, protons of these energies are known to contribute to single-event upsets in spacecraft electronics.3 Transient population protons can also reach higher latitudes than the typical inner radiation belt protons and may pose an additional radiation hazard to the crew of the International Space Station (ISS).4 Peak levels of extravehicular activity will occur during the construction phase of ISS, which coincides with the upcoming solar maximum. These energetic protons are not taken into account in models of inner-zone protons, which are based on data taken during the maxima of solar cycles 20 and 21 (which were relatively mild compared with the maxima of solar cycles 19 and 22).
The current prediction for the upcoming (cycle 23) solar maximum is that its activity level will be comparable to that of the previous solar maximum in 1989-1991.5 The transient populations produced by CME-generated interplanetary shocks were discovered only at the last solar maximum (and rediscovered to have occurred in preceding solar cycles that had had scant documentation), and so there is little calibrated predictive capability for the upcoming solar maximum. Earlier limited spacecraft coverage (both upstream in the solar wind and within the appropriate radiation belt region of the magnetosphere) supplied few constraints for dynamic models.
On March 13, 1989, the Hydro-Quebec Power System experienced a catastrophic failure resulting from its interaction with geomagnetically induced currents (GICs). The cause was probably the arrival of an interplanetary disturbance produced by a CME days earlier on the Sun. Although the Hydro-Quebec incident was the greatest problem of its kind during the previous solar maximum, less severe geomagnetic storms in September 1989 and October 1991 also created power system anomalies. In the Hydro-Quebec case, geomagnetic fluctuations had apparently coupled electromagnetically into the system, producing transformer saturation at many sites and causing voltages in the system to exceed safety margins. Widespread power blackouts that accompany such events produce a variety of problems. Oak Ridge National Laboratory assessed the potential impact of a widespread blackout in the Northeast United States as a result of a slightly more severe March 1989-type storm event. Its estimate of the impact to the gross domestic product alone put total economic costs in the $3 billion to $6 billion range,6 which is comparable to the damage caused by a major natural disaster such as Hurricane Hugo. The Northeast, in fact, was found to be particularly vulnerable to GICs. Protections can be installed, but it is impossible to completely protect an extensive power grid from GIC effects. However, evasive measures (such as rerouting the distribution) can be taken if there is sufficient warning and the power industry is prepared to respond.7
Instruments on UARS are continuing a two-decade time-series of space-based measurements of the solar constant.8 However, neither the UARS measurements nor those currently being considered as part of the EOS or National Polar-orbiting Environmental Satellite System (NPOESS) programs can elucidate the souce(s) of solar irradiance variability. Images in various spectral lines and bands obtained on SOHO have already revealed the wealth of different features on the Sun and hint at their control by solar magnetism. Assuming the continued operation of UARS and its solar irradiance monitor, we will have the opportunity to observe simultaneously how different solar features evolve with the changes in the solar magnetic field and affect the total irradiance. These observations will finally allow us to identify the sources of solar irradiance variations across a large part of the solar spectrum.
With SOHO, Yohkoh, Winf, IMP-8, and ACE, researchers can begin to distinguish among the varying causes and effects of flares and CMEs as the frequencies of both increase with increasing sunspot number. Using helioseismology techniques on SOHO and from complementary ground-based observatories such as the Global Oscillations Network Group (GONG), we can also begin to understand how the solar dynamo produces the diversity of solar features that affect life on Earth: sunspots, faculae and the active network that make the solar constant a variable; flares with their complex sunspot region connection and their many energetic emissions that can directly affect Earth's atmosphere; and the separable but sometimes related CMEs that produce a panoply of interplanetary and geophysical effects, including geomagnetic storms.9 With SAMPEX, FAST, Polar, and Geotail, researchers can observe the geospace responses to these different solar stimuli, and (from the ground and suborbital platforms) the atmospheric and ionospheric consequences.
Another technological development since the last solar activity cycle is the widespread availability of the World Wide Web (WWW). This Internet-based information system has completely revolutionized the way researchers access the latest information and tools, and analyze and exchange data. The importance of the Web and the advent of computers capable of the near-real-time global numerical simulation of space weather events cannot be overemphasized. Through these capabilities and modeling efforts such as those mentioned below, researchers are poised to acquire a physical understanding of Sun-Earth coupling at solar maximum that was never before possible.
The upcoming solar maximum also provides opportunities to test and refine models and simulations of solar activity. The development of both models and computers capable of the near-real-time global magnetohyrodynamic simulation of a long-duration (i.e., >1 day) event was demonstrated for the January 6-11, 1997, magnetic cloud. A modular approach to developing a geospace general circulation model is under way as part of the NSF-sponsored Geospace Environment Modeling (GEM) program. Its purpose is to provide a modeling capability in support of the NSWP goals that can be benchmarked against the body of data collected from ISTP satellite and coordinated ground-based studies. The models are being tested against data from the solar minimum and the current rise toward maximum. The extreme events of solar maximum like those ensuing from the March 1989 and 1991 storm periods are expected to provide the most stringent tests for the model development, but only if the relevant spacecraft data are available to constrain the models.
Having a full suite of solar and geospace instrumentation in place will also provide spinoffs in other disciplines of space science: Astronomers will have new insights into stellar magnetism and emissions, astrophysicists will find new analogies regarding particle sources and acceleration mechanisms in stellar environments, investigators in the Origins program will better understand the central stars in their extrasolar planetary systems and the effects of those stars on their surrounding planets, planetary scientists will have a basis for better modeling past Martian climate variability and for understanding how an active early Sun affected conditions on the surface of Mars (and Earth), and Earth scientists will have the information needed to physically model solar variability effects on our own planet.
Researchers recognize that each solar cycle is unique in its impact on Earth's environment. Solar cycles 19 and 22 were extremely active, cycles 20 and 21 comparatively benign. We now have a unique capability to capitalize on whatever the Sun generates that will affect Earth's environment during the maximum in solar cycle 23. The observations and the scientific results forthcoming from a concerted effort by the solar-terrestrial community will enhance the basic understanding of solar phenomena, which will in turn improve the predictability of environmental perturbations that affect Earth satellites, communications, power grid disruptions, and other aspects of technology that affect our lives.
http://www.nas.edu/ssb/maxch3.htm Resource List at bottom of page
|Subj: [SO] SOHO Sees Right Through the Sun
Source: European Space Agency
March 9, 2000
SOHO sees right through the Sun, and finds sunspots on the far side
One of the highest hopes for SOHO, the European Space Agency (ESA)-NASA spacecraft is fulfilled with the detection of sunspots on the invisible far side of the Sun. This scientific marvel promises practical benefits. It could give an extra week's warning of possible bad weather in space, to astronauts and operators of satellites, power networks and other systems liable to be affected by eruptions on the Sun linked to sunspots.
The story is told today in the journal Science by Charles Lindsey of Tucson, Arizona, and Doug Braun of Boulder, Colorado. They realised that the analytical witchcraft called helioseismic holography might open a window right through the Sun. And the technique worked when they used it to decode waves seen on the visible surface by one of SOHO's instruments, the Michelson Doppler Imager, or MDI.
"We've known for ten years that in theory we could make the Sun transparent all the way to the far side," said Charles Lindsey."But we needed observations of exceptional quality. In the end we got them, from MDI on SOHO."
For more than 100 years scientists have been aware that groups of dark sunspots on the Sun's visible face are often the scene of flares and other eruptions. Nowadays they watch the Sun more closely than ever, because modern systems are much more vulnerable to solar disturbances than old-style technology was.
The experts can still be taken by surprise, because the Sun turns on its axis. A large group of previously hidden sunspots can suddenly swing into view on the eastern (left-hand) edge of the Sun. It may already be blazing away with menacing eruptions. With a far-side preview of sunspots, nasty shocks for the space weather forecasters may now be avoidable.
Last year, French and Finnish scientists used SWAN, another instrument on SOHO, to detect activity on the far side. They saw an ultraviolet glow lighting up gas in the Solar System beyond the Sun, and moving across the sky like a lighthouse beam as the Sun rotated. The method used by Lindsey and Braun with MDI data is completely different, and it pinpoints the source of the activity on the far side.
Solar seismology chalks up another success
Detection of sound waves reverberating through the Sun opened its gassy interior for investigation, in much the same way as seismologists learned to explore the Earth's rocky interior with earthquake waves.
Using special telescopes on the ground and in space, helioseismologists detect many different modes of vibration appearing at the Sun's surface, all with tales to tell about how the interior is structured and how the gas moves about.
The SOHO spacecraft is an ideal platform for helioseismology because its station 1.5 million kilometres out in space allows it to watch the Sun for 24 hours a day. Its own motions are very gentle - an important consideration when scientists are looking for subtle motions on the Sun's surface.
Developed and operated by a Californian team, the MDI instrument is the most elaborate of three helioseismic instruments on SOHO. It measures rhythmic motions at a million points across the Sun's visible surface.
Computers can interpret the motions in terms of sound waves travelling through the Sun. The waves are affected by the various layers and movements of gas that they encounter. MDI has already revealed many unknown features of the interior, including layers where the speed of the gas changes abruptly and hidden jet streams circling the Sun's poles. The team is also discovering what goes on underneath sunspots on the near side of the Sun.
Philip Scherrer of Stanford University, California, leads the MDI team. He is gratified but not surprised that his instrument has chalked up another success, with the detection of sunspots on the far side.
"Up till now we've explored the Sun's interior quite thoroughly from the near surface down to the core," Scherrer commented. "Charlie Lindsey and Doug Braun told me many years ago how they hoped to use MDI on SOHO to see all the way to the far side. I was always sure they could do it."
The technique of helioseismic holography used by Lindsey and Braun examines a wide ring of sound waves that emanate from a small region on the far side, and reach the near side by rebounding internally from the solar surface. A sunspot group reveals itself because the Sun's surface is depressed and very strong magnetic fields speed up the sound waves.
As a result the sound waves arrive at the front side about 6 seconds earlier than equivalent waves from sunspot-free regions, in a total travel time of about 3 hours. The change in speed becomes evident when sound waves shuttling back and forth get out of step with one another.
MDI data for 28-29 March 1998 revealed, on the far side, a sunspot group that was not plainly visible on the near side until ten days later. Observations for 24 hours were more than sufficient to detect the sunspots, which means that routine monitoring is a realistic possibility.
"The far-side sunspots are a good example of why this spacecraft is so exciting to work with," said Bernhard Fleck, ESA's project scientist for SOHO. "We can make a completely new discovery in fundamental solar physics, and immediately think of applying it to the practical task of monitoring the daily activity of the Sun and predicting its effects on the Earth."
The SOHO project is an international cooperation between the European Space Agency (ESA) and NASA. The spacecraft was built in Europe for ESA and equipped with instruments by teams of scientists in Europe and the USA. NASA launched SOHO in December 1995, and in 1998 ESA and NASA decided to extend its highly successful operations until 2003.
For more information, please contact:
ESA - Communication Department
Media Relations Office
|Subj: [earthchanges] Fwd: [TimeStar] Milestone -- Sun's north and south
SHARING LIGHT, LEE GUILMETTE CHIN
Date: Sun, 04 Feb 2001 02:19:11 -0000
Reversal of the sun's north and south magnetic poles is nearly complete according to a survey made by the Ulysses spacecraft in January. You may remember that I suspected the sun's poles had reversed in August based on a new solar pattern I found in the calendar glyphs. I asked the egroup to watch for news about changes in the solar cycle.
James Kennedy forwarded an article on the two-week survey done by the Ulysses spacecraft in January today (February 3). I've included the text of the article and a link to the web site that published the article.
After predicting periods when Class X solar flares were possible for four years, the pattern began to skew last summer. Solar activity fell to extremely low levels during windows when flares should have been high. Then large solar flares began to erupt during windows opposite the previous four years. The reversal of glyphs associated with solar activity indicated that the sun's magnetic poles might have changed.
The November 8 solar storm mentioned in the article on the pole reversal was predicted with the TimeStar based on the new pattern I had found. The largest solar flare since November came during the window when I had predicted the possibility of large flares based on the new pattern pointed out by the calendar glyphs.
No other predictive method identified the reversal of the sun's magnetic poles that was confirmed by the Ulysses spacecraft five months after I announced the reversal to the TimeStar egroup. The ability to predict a reversal of the sun's magnetic poles with the pattern of calendar glyphs is a milestone in interpreting the scientific foundation of the ancient calendar. The evidence to prove that the ancient timekeepers used an astronomical system that was unknown to European astronomers has been acquired. The TimeStar's capacity for predicting trends in the earth grid with 13-day windows has been proven.
The scientific model embodied in the proto-Mayan calendar was explained in a "UFO" contact with humans who reported that they had encoded the science of the ancient calendar in the pyramids. The ancient astronauts who encoded the calendar in the pyramids at Teotihuacan are the same astronauts who inspired the TimeStar. They taught the cosmic science of the ancient calendar to the natives of Mexico then explained the science to me in the 20th Century.
The proofs and evidence of the TimeStar are established, and the groundwork is laid to work with a new chapter of cosmic science in a more personal way. The ancients understood that the sun was the governor of life on Earth. A new world era based on the solar cycle within a changing cosmic environment began in 1991. Among the many changes I predicted in 1996 was a steady increase in brain diseases that included mad cow disease. Mad cow disease has now spread worldwide and the number of autistic births has increased more than 500% since 1991. The potentials of these problems were pointed out in Teotihuacan's focus on brain function.
The potential for activating higher brain functions to reach the next level of Homo sapien's evolution is offered with the new world era. Failure to develop Homo sapien's potential to the next level results in disease. Nature will remove those life forms that do not develop with her cycles of evolution. Secret government black projects don't have to design new diseases to clear away overpopulation. Nature is taking care of this herself, and the black projects will be part of what Nature removes if they don't get a grip on personal evolution.
Activating higher human functions is the focus necessary for the cycle that began with the World Bridger eclipse on January 9, 2001.
Struggle Seen As Sun Switches Magnetic Field Polarity During solar maximum, when the Sun's activity is at a peak in its 11 year cycle, the polarity of its magnetic field changes: the north pole takes on the polarity of the south pole and vice versa. Now, for the first time ever, a spacecraft has witnessed this process from a front-row seat high above the Sun's south pole. On January 16, the European Southern Observatory (ESA)'s Ulysses spacecraft completed its four-month southern solar polar passage as solar activity reached its peak.
Did Ulysses see the Sun's polarity switch?
Andre Balogh, from Imperial College, London, who is Principal Investigator for the Ulysses magnetometer, says:
"In the past few months, the direction of the magnetic field observed by Ulysses fluctuated between the old and the new. Even now, there are periods when the old polarity is still present.
"Clearly, a struggle is going on in the Sun's magnetic field, with freshly emerging new polarity regions racing towards the polar regions, encountering the slowly decaying older polarity regions. We know that the new polarity will win through, but the battle is still on for another few months."
Viewed from the Earth, the Sun's magnetic field seems to have already switched. At the ESLAB symposium last October, Todd Hoeksema from NASA headquarters reported that ground-based observatories had already noticed the change.
Balogh points out, however, that "the Earth is not the ideal vantage point to see what happens at high heliolatitudes. We are witnessing a complex process in which different phenomena signal reversal processes at different times and in different ways. This is why Ulysses, flying over the polar regions, is much better placed to observe the disappearance of the old magnetic polarities and the appearance of the new."
The Ulysses probe continues to weather the effects of numerous solar storms churned up by the magnetic turmoil welling up from deep within the Sun's interior. These storms release large numbers of energetic particles that stream away from the Sun.
One particularly strong solar storm occurred around midnight on November 8 last year. Spacecraft in orbit around the Earth recorded large numbers of energetic particles generated by it. The surprise was that Ulysses also detected the storm's effects at about the same time.
"Most of the activity on the Sun is taking place around 200 north.The surprise is that we're seeing almost identical signatures over the pole. The highly energetic particles must cross magnetic field lines to reach such high latitudes, which suggests that the field lines must be very tangled up.
"We know that the magnetic field configuration is completely different from how it was at solar minimum -- and these particle observations will help us to understand these differences in detail," says Richard Marsden, Ulysses Project Scientist from ESTEC, the Netherlands, who has been examining data from the COSPIN experiment on board Ulysses.
"The Sun's magnetism is very complex," adds Balogh. "Given this unique chance to sit by the ringside as the two magnetic polarities fight it out, Ulysses is once again able to make a significant step forward in our understanding of the Sun and the heliosphere."
On January 16, Ulysses crossed the 70th solar parallel, marking the end of its second passage above the south pole. The first time Ulysses visited the south pole, in 1994, the Sun was near its activity minimum. By the time the spacecraft begins its north polar passage on September 3, the activity should have begun to decline again. 29-Jan-2001
Space Weather News for March 2, 2001
SOLAR ACTIVITY: This week the face of the Sun looked remarkably blank as the sunspot number dropped to its lowest level in three months. But there's more to solar activity than sunspots! On February 28th a filament collapsed on the Sun and the eruption sent a coronal mass ejection toward Earth. The expanding cloud will likely reach our planet on Saturday, March 3rd, and trigger high latitude auroras.
For more information about this and other space weather news, please visit http://www.spaceweather.com.
THE SUN'S MAGNETIC FIELD
The Sun Does a Flip
NASA scientists who monitor the Sun say that our star's awesome magnetic field is flipping -- a sure sign that solar maximum is here.
February 15, 2001 -- You can't tell by looking, but scientists say the Sun has just undergone an important change. Our star's magnetic field has flipped.
The Sun's magnetic north pole, which was in the northern hemisphere just a few months ago, now points south. It's a topsy-turvy situation, but not an unexpected one.
"This always happens around the time of solar maximum," says David Hathaway, a solar physicist at the Marshall Space Flight Center. "The magnetic poles exchange places at the peak of the sunspot cycle. In fact, it's a good indication that Solar Max is really here."
Above: Sunspot counts, plotted here against an x-ray image of the Sun, are nearing their maximum for the current solar cycle. [more information]
The Sun's magnetic poles will remain as they are now, with the north magnetic pole pointing through the Sun's southern hemisphere, until the year 2012 when they will reverse again. This transition happens, as far as we know, at the peak of every 11-year sunspot cycle -- like clockwork.
Earth’s magnetic field also flips, but with less regularity. Consecutive reversals are spaced 5 thousand years to 50 million years apart. The last reversal happened 740,000 years ago. Some researchers think our planet is overdue for another one, but nobody knows exactly when the next reversal might occur.
Although solar and terrestrial magnetic fields behave differently, they do have something in common: their shape. During solar minimum the Sun's field, like Earth's, resembles that of an iron bar magnet, with great closed loops near the equator and open field lines near the poles. Scientists call such a field a "dipole." The Sun's dipolar field is about as strong as a refrigerator magnet, or 50 gauss (a unit of magnetic intensity). Earth's magnetic field is 100 times weaker.
Below: The Sun's basic magnetic field, like Earth's, resembles that of a bar magnet.
When solar maximum arrives and sunspots pepper the face of the Sun, our star's magnetic field begins to change. Sunspots are places where intense magnetic loops -- hundreds of times stronger than the ambient dipole field -- poke through the photosphere.
"Meridional flows on the Sun's surface carry magnetic fields from mid-latitude sunspots to the Sun's poles," explains Hathaway. "The poles end up flipping because these flows transport south-pointing magnetic flux to the north magnetic pole, and north-pointing flux to the south magnetic pole." The dipole field steadily weakens as oppositely-directed flux accumulates at the Sun's poles until, at the height of solar maximum, the magnetic poles change polarity and begin to grow in a new direction.
Hathaway noticed the latest polar reversal in a "magnetic butterfly diagram." Using data collected by astronomers at the U.S. National Solar Observatory on Kitt Peak, he plotted the Sun's average magnetic field, day by day, as a function of solar latitude and time from 1975 through the present. The result is a sort of strip chart recording that reveals evolving magnetic patterns on the Sun's surface. "We call it a butterfly diagram," he says, "because sunspots make a pattern in this plot that looks like the wings of a butterfly."
In the butterfly diagram, pictured below, the Sun's polar fields appear as strips of uniform color near 90 degrees latitude. When the colors change (in this case from blue to yellow or vice versa) it means the polar fields have switched signs.
In this "magnetic butterfly diagram," yellow regions are occupied by south-pointing magnetic fields; blue denotes north. At mid-latitudes the diagram is dominated by intense magnetic fields above sunspots. During the sunspot cycle, sunspots drift, on average, toward the equator -- hence the butterfly wings. The uniform blue and yellow regions near the poles reveal the orientation of the Sun's underlying dipole magnetic field. [more information]
The ongoing changes are not confined to the space immediately around our star, Hathaway added. The Sun's magnetic field envelops the entire solar system in a bubble that scientists call the "heliosphere." The heliosphere extends 50 to 100 astronomical units (AU) beyond the orbit of Pluto. Inside it is the solar system -- outside is interstellar space.
"Changes in the Sun's magnetic field are carried outward through the heliosphere by the solar wind," explains Steve Suess, another solar physicist at the Marshall Space Flight Center. "It takes about a year for disturbances to propagate all the way from the Sun to the outer bounds of the heliosphere."
Because the Sun rotates (once every 27 days) solar magnetic fields corkscrew outwards in the shape of an Archimedian spiral. Far above the poles the magnetic fields twist around like a child's Slinky toy.
Left: Steve Suess (NASA/MSFC) prepared this figure, which shows the Sun's spiraling magnetic fields from a vantage point ~100 AU from the Sun.
Because of all the twists and turns, "the impact of the field reversal on the heliosphere is complicated," says Hathaway. Sunspots are sources of intense magnetic knots that spiral outwards even as the dipole field vanishes. The heliosphere doesn't simply wink out of existence when the poles flip -- there are plenty of complex magnetic structures to fill the void.
Or so the theory goes.... Researchers have never seen the magnetic flip happen from the best possible point of view -- that is, from the top down.
But now, the unique Ulysses spacecraft may give scientists a reality check. Ulysses, an international joint venture of the European Space Agency and NASA, was launched in 1990 to observe the solar system from very high solar latitudes. Every six years the spacecraft flies 2.2 AU over the Sun's poles. No other probe travels so far above the orbital plane of the planets.
"Ulysses just passed under the Sun's south pole," says Suess, a mission co-Investigator. "Now it will loop back and fly over the north pole in the fall."
Right: Following an encounter with Jupiter in 1992, the Ulysses spacecraft went into a high polar orbit. It's maximum solar latitude is 80.2 degrees south. [more]
"This is the most important part of our mission," he says. Ulysses last flew over the Sun's poles in 1994 and 1996, during solar minimum, and the craft made several important discoveries about cosmic rays, the solar wind, and more. "Now we get to see the Sun's poles during the other extreme: Solar Max. Our data will cover a complete solar cycle."
To learn more about the Sun's changing magnetic field and how it is generated, please visit "The Solar Dynamo," a web page prepared by the NASA/Marshall solar research group. Updates from the Ulysses spacecraft may be found on the Internet from JPL at http://ulysses.jpl.nasa.gov.
Revelation of the Sun
How We Tell Time In The Solar System
Signs In The Sky
The Solar Eclipse of 1999
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