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  • richardmitnick 9:32 am on May 1, 2015 Permalink | Reply
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    From NASA Science- “Fire and Ice: A MESSENGER Recap” 

    NASA Science Science News

    April 30, 2015
    Dr. Tony Phillips

    1
    The colors of the solar system’s innermost planet are enhanced in this tantalizing view, based on global image data from the Mercury-orbiting MESSENGER spacecraft. Human eyes would not discern the clear color differences but they are real none the less, indicating distinct chemical, mineralogical, and physical regions across the cratered surface. Notable at the upper right, Mercury’s large, circular, tan colored feature known as the Caloris basin was created by an impacting comet or asteroid during the solar system’s early years. The ancient basin was subsequently flooded with lava from volcanic activity, analogous to the formation of the lunar maria. Color contrasts also make the light blue and white young crater rays, material blasted out by recent impacts, easy to follow as they extend across a darker blue, low reflectance terrain.

    Mission controllers at the Johns Hopkins University Applied Physics Laboratory in Laurel, Maryland, have confirmed that MESSENGER slammed into the surface of Mercury on April 30th at 3:26 p.m. EDT. It had used the last of its propellant on April 24th and could no longer maintain a stable orbit. Traveling some 8,750 mph, the plummeting spacecraft made an unseen crater on the side of the planet facing away from Earth.

    NASA Messenger satellite
    Messenger

    “Going out with a bang as it impacts the surface of Mercury, we are celebrating MESSENGER as more than a successful mission,” says John Grunsfeld, associate administrator for the Science Mission Directorate at NASA Headquarters in Washington. “Now, we begin the next phase of this mission–analyzing the exciting data already in the archives, and unravelling the mysteries of Mercury.”

    Here are some of MESSENGER’s most important findings so far:

    The hidden face of Mercury: In the mid-1970s when Mariner 10 flew past Mercury three times, the probe imaged less than half the planet.

    NASA Mariner 10
    Mariner 10

    Until MESSENGER arrived, the rest of Mercury was a land of mystery. MESSENGER was the first spacecraft to view the entirety of the mighty Caloris basin—one of the biggest and youngest impact features in the solar system. Moreover, MESSENGER spotted volcanic vents around the rim of the basin, proving that volcanism—and not only impacts—have shaped the surface of the innermost planet.

    The irony of Mercury’s poles: Mercury would seem to be an unlikely place to find ice. But the tilt of Mercury’s rotational axis is almost zero – less than one degree – so the floors of craters at the planet’s poles never see sunlight. Scientists suggested decades ago that there might be frozen water trapped there. The idea received a boost in 1991 when the Arecibo radio telescope in Puerto Rico and the Goldstone antenna in California detected unusually bright radar reflections from Mercury’s poles—the kind of reflections that ice would make. From Mercury orbit, MESSENGER was able to look down on Mercury’s poles like no other spacecraft or telescope, and it confirmed the unlikely: Permanently shadowed craters near Mercury’s poles have temperatures less than -280F (-173C), and water ice is stable on their dark inner surfaces. Some of the polar ice is covered by a mysterious dark organic material that researchers still do not understand.

    Arecibo Observatory
    Arecibo Radio Telescope

    NASA DSCC Goldstone Antenna
    NASA DSCC Goldstone Antenna

    2
    These graphics show the predicted location and time of MESSENGER’s impact on Mercury’s surface.

    The incredible shrinking planet: The dominant tectonic landforms on Mercury are huge cliffs called “lobate scarps.” Even before MESSENGER, researchers thought these scarps were signs of global shrinkage, like wrinkles on a raisin. Why would Mercury shrink? The planet’s core makes up a whopping 60–70% of its mass. Cooling of this oversized core has led to a remarkable contraction of the planet. MESSENGER’s images of lobate scarps show that the total contraction is two to seven times greater than researchers previously thought.

    Magnetically speaking, Mercury is alive: Until Mariner 10 discovered Mercury’s magnetic field in the 1970s, Earth was the only other terrestrial planet known to have a global magnetic field. Earth’s magnetism is generated by the planet’s churning hot, liquid-iron core via a mechanism called a magnetic dynamo. Researchers have been puzzled by Mercury’s field because its iron core was supposed to have finished cooling long ago and stopped generating magnetism. Some researchers thought that the field may have been a relic of the past, frozen in the outer crust. MESSENGER data show otherwise: Mercury’s field appears to be generated by an active dynamo in the planet’s core. It is not a relic.

    A planet with a tail: Orbiting Mercury, MESSENGER made the first in situ observations of Mercury’s unique exosphere. The exosphere is an ultrathin atmosphere where atoms and molecules are so far apart they are more likely to collide with the surface than with each other. This material is derived mainly from the surface of Mercury itself, knocked aloft by solar radiation, solar wind bombardment and meteoroid vaporization. MESSENGER was able to determine the chemical composition of the exosphere (hydrogen, helium, sodium, potassium, and calcium) and monitor the material as it was stretched out into a comet-like tail as long as 2 million km by the action of the solar wind. This tail, as well as Mercury’s magnetic field, was often buffeted by solar activity during MESSENGER’s long mission, giving the spacecraft a point-blank view of the roughest space weather in the solar system.

    In addition to science discoveries, the mission provided many technological firsts, including the development of a ceramic cloth sunshade that protected the spacecraft’s instruments and electronics from fierce solar radiation.

    “The front side of the sunshade routinely experienced temperatures in excess of 300° Celsius (570° Fahrenheit), whereas the majority of components in its shadow routinely operated near room temperature (20°C or 68°F),” said Helene Winters, mission project manager at the Johns Hopkins University Applied Physics Laboratory (APL). “This technology to protect the spacecraft’s instruments was a key to mission success during its prime and extended operations.”

    Goodbye, MESSENGER, and thanks!

    See the full article here.

    Please help promote STEM in your local schools.

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    NASA leads the nation on a great journey of discovery, seeking new knowledge and understanding of our planet Earth, our Sun and solar system, and the universe out to its farthest reaches and back to its earliest moments of existence. NASA’s Science Mission Directorate (SMD) and the nation’s science community use space observatories to conduct scientific studies of the Earth from space to visit and return samples from other bodies in the solar system, and to peer out into our Galaxy and beyond. NASA’s science program seeks answers to profound questions that touch us all:

    This is NASA’s science vision: using the vantage point of space to achieve with the science community and our partners a deep scientific understanding of our planet, other planets and solar system bodies, the interplanetary environment, the Sun and its effects on the solar system, and the universe beyond. In so doing, we lay the intellectual foundation for the robotic and human expeditions of the future while meeting today’s needs for scientific information to address national concerns, such as climate change and space weather. At every step we share the journey of scientific exploration with the public and partner with others to substantially improve science, technology, engineering and mathematics (STEM) education nationwide.

    NASA

     
  • richardmitnick 4:39 am on March 20, 2015 Permalink | Reply
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    From NASA Science: “The Mystery of Nanoflares” 

    NASA Science Science News

    March 19, 2015
    Dr. Tony Phillips

    When you attach the prefix “nano” to something, it usually means “very small.” Solar flares appear to be the exception. Researchers are studying a type of explosion on the sun called a ‘nanoflare.’ A billion times less energetic than ordinary flares, nanoflares have a power that belies their name. “A typical ‘nanoflare’ has the same energy as 240 megatons of TNT,” says physicist David Smith of UC Santa Cruz. “That would be something like 10,000 atomic fission bombs.”


    A new ScienceCast video explores the mystery of the sun’s tiniest flares.

    The sun can go days, weeks or even months without producing an ordinary solar flare. Nanoflares, on the other hand, are crackling on the sun almost non-stop. “They appear as little brightenings of the solar surface at extreme ultraviolet and X-ray wavelengths,” continues Smith. “The first sightings go back to Skylab in the 1970s.”

    The relentless crackle of nanoflares might solve a long-standing mystery in solar physics: What causes the sun’s corona to be so hot? Imagine standing in front of a roaring fire. You feel the warmth of the flames. Now back away. You get cooler, right? That’s not how it works on the sun. The visible surface of the sun has a temperature of 5500 C. Moving away from the surface should provide some relief. Instead, the sun’s upper atmosphere, known as the “solar corona,” sizzles at a million degrees–a temperature almost 200 times higher than that of the roaring furnace below.

    For more than a half-century, astronomers have tried to figure out what causes the corona to be so hot. Every year or so, a press release appears purporting to solve the mystery, only to be shot down by a competing theory a year or so later. It is one of the most vexing problems in astrophysics.

    2
    X-rays stream off the sun in this image showing observations from by NASA’s Nuclear Spectroscopic Telescope Array, or NuSTAR, overlaid on a picture taken by NASA’s Solar Dynamics Observatory (SDO).

    NASA SDO
    SDO

    NASA NuSTAR
    Nu-StAR

    Smith thinks nanoflares might be involved. For one thing, they appear to be active throughout the solar cycle, which would explain why the corona remains hot during Solar Minimum. And while each individual nanoflare falls short of the energy required to heat the sun’s atmosphere, collectively they might have no trouble doing to job.

    To investigate this possibility, Smith turned to a telescope designed to study something completely different.

    Launched in 2012, NASA’s NuSTAR X-ray telescope is on a mission to study black holes and other extreme objects in the distant cosmos. Solar scientists first thought of using NuSTAR to study the sun about seven years ago, after the space telescope’s design and construction was underway. Smith contacted the principal investigator, Fiona Harrison of the California Institute of Technology in Pasadena, to see what she thought.

    “At first I thought the whole idea was crazy,” says Harrison. “Why would we have the most sensitive high energy X-ray telescope ever built, designed to peer deep into the universe, look at something in our own back yard?”

    Eventually, she was convinced. As Smith explained, NuSTAR has just the right combination of sensitivity and resolution to study the telltale X-ray flickers of nanoflares. A test image they took in late 2014 removed any doubt. NuSTAR turned toward the sun and, working together with NASA’s Solar Dynamics Observatory, captured one of the most beautiful images in the history of solar astronomy.

    The next step, says Smith, is to wait for Solar Minimum. The current solar cycle will wind down in the years ahead, leaving the sun mostly free of sunspots and other magnetic clutter that can obscure nanoflares. NuSTAR will be able to survey the stellar surface and gather data on these explosions like no telescope has done before.

    Will it solve the mystery of nanoflares and the solar corona? “I don’t know,” says Smith, “but I cannot wait to try.”

    See the full article here.

    Please help promote STEM in your local schools.

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    Stem Education Coalition

    NASA leads the nation on a great journey of discovery, seeking new knowledge and understanding of our planet Earth, our Sun and solar system, and the universe out to its farthest reaches and back to its earliest moments of existence. NASA’s Science Mission Directorate (SMD) and the nation’s science community use space observatories to conduct scientific studies of the Earth from space to visit and return samples from other bodies in the solar system, and to peer out into our Galaxy and beyond. NASA’s science program seeks answers to profound questions that touch us all:

    This is NASA’s science vision: using the vantage point of space to achieve with the science community and our partners a deep scientific understanding of our planet, other planets and solar system bodies, the interplanetary environment, the Sun and its effects on the solar system, and the universe beyond. In so doing, we lay the intellectual foundation for the robotic and human expeditions of the future while meeting today’s needs for scientific information to address national concerns, such as climate change and space weather. At every step we share the journey of scientific exploration with the public and partner with others to substantially improve science, technology, engineering and mathematics (STEM) education nationwide.

    NASA

     
  • richardmitnick 4:31 am on January 8, 2015 Permalink | Reply
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    From NASA Science: “Hubble: Pillars of Creation are also Pillars of Destruction” 

    NASA Science Science News

    Jan. 7, 2015
    Dr. Tony Phillips

    Although NASA’s Hubble Space Telescope has taken many breathtaking images of the universe, one snapshot stands out from the rest: the iconic view of the so-called “Pillars of Creation.” The jaw-dropping photo, taken in 1995, revealed never-before-seen details of three giant columns of cold gas bathed in the scorching ultraviolet light from a cluster of young, massive stars in a small region of the Eagle Nebula, or M16.

    e
    Overview of some famous sights in the Eagle Nebula

    NASA Hubble Telescope
    Hubble

    In celebration of its upcoming 25th anniversary in April, Hubble has revisited the famous pillars, providing astronomers with a sharper and wider view. Although the original image was dubbed the Pillars of Creation, the new image hints that they are also “pillars of destruction.”

    p
    Astronomers using NASA’s Hubble Space Telescope have assembled a bigger and sharper photograph of the iconic Eagle Nebula’s “Pillars of Creation”. Credit: NASA/ESA/Hubble Heritage Team (STScI/AURA)/J. Hester, P. Scowen (Arizona State U.)

    “I’m impressed by how transitory these structures are,” explains Paul Scowen of Arizona State University in Tempe. “They are actively being ablated away before our very eyes. The ghostly bluish haze around the dense edges of the pillars is material getting heated up and evaporating away into space. We have caught these pillars at a very unique and short-lived moment in their evolution.” Scowen and astronomer Jeff Hester, formerly of Arizona State University, led the original Hubble observations of the Eagle Nebula.


    HUBBLECast 82

    The original 1995 images were taken in visible light. The new image includes near-infrared light as well. The infrared view transforms the pillars into eerie, wispy silhouettes seen against a background of myriad stars. That’s because the infrared light penetrates much of the gas and dust, except for the densest regions of the pillars. Newborn stars can be seen hidden away inside the pillars.

    The infrared image shows that the very ends of the pillars are dense knots of dust and gas. They shadow the gas below them, keeping the gas cool and creating the long, column-like structures. The material in between the pillars has long since been evaporated away by the ionizing radiation from the central star cluster located above the pillars.

    At the top edge of the left-hand pillar, a gaseous fragment has been heated up and is flying away from the structure, underscoring the violent nature of star-forming regions. “These pillars represent a very dynamic, active process,” Scowen said. “The gas is not being passively heated up and gently wafting away into space. The gaseous pillars are actually getting ionized, a process by which electrons are stripped off of atoms, and heated up by radiation from the massive stars. And then they are being eroded by the stars’ strong winds and barrage of charged particles, which are literally sandblasting away the tops of these pillars.”

    When Scowen and Hester used Hubble to make the initial observations of the Eagle Nebula in 1995, astronomers had seen the pillar-like structures in ground-based images, but not in detail. They knew that the physical processes are not unique to the Eagle Nebula because star birth takes place across the universe. But at a distance of just 6,500 light-years, M16 is the most dramatic nearby example – as the team soon realized.

    As Scowen was piecing together the Hubble exposures of the Eagle, he was amazed at what he saw. “I called Jeff Hester on his phone and said, ‘You need to get here now,’” Scowen recalled. “We laid the pictures out on the table, and we were just gushing because of all the incredible detail that we were seeing for the very first time.”

    The first features that jumped out at the team in 1995 were the streamers of gas seemingly floating away from the columns. Astronomers had previously debated what effect nearby massive stars would have on the surrounding gas in stellar nurseries. “There is the only one thing that can light up a neighborhood like this: massive stars kicking out enough horsepower in ultraviolet light to ionize the gas clouds and make them glow,” Scowen said. “Nebulous star-forming regions like M16 are the interstellar neon signs that say, ‘We just made a bunch of massive stars here.’ This was the first time we had directly seen observational evidence that the erosionary process, not only the radiation but the mechanical stripping away of the gas from the columns, was actually being seen.”

    o
    The original 1995 image was beautiful.

    By comparing the 1995 and 2014 pictures, astronomers also noticed a lengthening of a narrow jet-like feature that may have been ejected from a newly forming star. The jet looks like a stream of water from a garden hose. Over the intervening 19 years, this jet has stretched farther into space, across an additional 60 billion miles, at an estimated speed of about 450,000 miles per hour.

    Our sun probably formed in a similar turbulent star-forming region. There is evidence that the forming solar system was seasoned with radioactive shrapnel from a nearby supernova. That means that our sun was formed as part of a cluster that included stars massive enough to produce powerful ionizing radiation, such as is seen in the Eagle Nebula. “That’s the only way the nebula from which the sun was born could have been exposed to a supernova that quickly, in the short period of time that represents, because supernovae only come from massive stars, and those stars only live a few tens of millions of years,” Scowen explained. “What that means is when you look at the environment of the Eagle Nebula or other star-forming regions, you’re looking at exactly the kind of nascent environment that our sun formed in.”

    See the full article here.

    Pillars in Near Infrared from ESO’s VLT
    3

    The 8.2-meter VLT’s ANTU telescope imaged the famous “Pillars of Creation” region and its surroundings in near-infrared using the ISAAC instrument. This enabled astronomers to penetrate the obscuring dust in their search to detect newly formed stars. The near-infrared results showed that 11 of the Pillars’ 73 evaporating gaseous globules (or EGGs) possibly contained stars, and that the tips of the pillars contain stars and nebulosity not seen in the Hubble image.

    ESA Video showing the Pillars in a variety of wavelengths.

    Please help promote STEM in your local schools.

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    The Hubble Space Telescope is a project of international cooperation between NASA and the European Space Agency. NASA’s Goddard Space Flight Center manages the telescope. The Space Telescope Science Institute (STScI), is a free-standing science center, located on the campus of The Johns Hopkins University and operated by the Association of Universities for Research in Astronomy (AURA) for NASA, conducts Hubble science operations.

    NASA leads the nation on a great journey of discovery, seeking new knowledge and understanding of our planet Earth, our Sun and solar system, and the universe out to its farthest reaches and back to its earliest moments of existence. NASA’s Science Mission Directorate (SMD) and the nation’s science community use space observatories to conduct scientific studies of the Earth from space to visit and return samples from other bodies in the solar system, and to peer out into our Galaxy and beyond. NASA’s science program seeks answers to profound questions that touch us all:

    This is NASA’s science vision: using the vantage point of space to achieve with the science community and our partners a deep scientific understanding of our planet, other planets and solar system bodies, the interplanetary environment, the Sun and its effects on the solar system, and the universe beyond. In so doing, we lay the intellectual foundation for the robotic and human expeditions of the future while meeting today’s needs for scientific information to address national concerns, such as climate change and space weather. At every step we share the journey of scientific exploration with the public and partner with others to substantially improve science, technology, engineering and mathematics (STEM) education nationwide.

    NASA

     
  • richardmitnick 3:09 pm on January 2, 2015 Permalink | Reply
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    From NASA Science: Weather on Hot Jupiters 

    NASA Science Science News

    Astronomers using NASA’s Spitzer Space Telescope are making weather maps of an exotic class of exoplanets called “hot Jupiters.” What they’re finding is wilder than anything we experience here in our own solar system.

    NASA Spitzer Telescope
    NASA Spitzer schematic
    Spitzer

    See the full article here.

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

    NASA leads the nation on a great journey of discovery, seeking new knowledge and understanding of our planet Earth, our Sun and solar system, and the universe out to its farthest reaches and back to its earliest moments of existence. NASA’s Science Mission Directorate (SMD) and the nation’s science community use space observatories to conduct scientific studies of the Earth from space to visit and return samples from other bodies in the solar system, and to peer out into our Galaxy and beyond. NASA’s science program seeks answers to profound questions that touch us all:

    This is NASA’s science vision: using the vantage point of space to achieve with the science community and our partners a deep scientific understanding of our planet, other planets and solar system bodies, the interplanetary environment, the Sun and its effects on the solar system, and the universe beyond. In so doing, we lay the intellectual foundation for the robotic and human expeditions of the future while meeting today’s needs for scientific information to address national concerns, such as climate change and space weather. At every step we share the journey of scientific exploration with the public and partner with others to substantially improve science, technology, engineering and mathematics (STEM) education nationwide.

    NASA

     
  • richardmitnick 3:35 pm on September 20, 2014 Permalink | Reply
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    From NASA: A Colorful Lunar Eclipse 

    NASA Science Science News

    Mark your calendar: On Oct. 8th, the Moon will pass through the shadow of Earth for a total lunar eclipse. Sky watchers in the USA will see the Moon turn a beautiful shade of celestial red and maybe turquoise, too. Watch, enjoy, learn.

    NASA leads the nation on a great journey of discovery, seeking new knowledge and understanding of our planet Earth, our Sun and solar system, and the universe out to its farthest reaches and back to its earliest moments of existence. NASA’s Science Mission Directorate (SMD) and the nation’s science community use space observatories to conduct scientific studies of the Earth from space to visit and return samples from other bodies in the solar system, and to peer out into our Galaxy and beyond. NASA’s science program seeks answers to profound questions that touch us all:

    This is NASA’s science vision: using the vantage point of space to achieve with the science community and our partners a deep scientific understanding of our planet, other planets and solar system bodies, the interplanetary environment, the Sun and its effects on the solar system, and the universe beyond. In so doing, we lay the intellectual foundation for the robotic and human expeditions of the future while meeting today’s needs for scientific information to address national concerns, such as climate change and space weather. At every step we share the journey of scientific exploration with the public and partner with others to substantially improve science, technology, engineering and mathematics (STEM) education nationwide.

    NASA

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  • richardmitnick 8:48 am on July 23, 2014 Permalink | Reply
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    From NASA Science News: “Near Miss: The Solar Superstorm of July 2012″ 

    NASA Science Science News

    NASA Science News

    July 23, 2014
    Dr. Tony Phillips

    If an asteroid big enough to knock modern civilization back to the 18th century appeared out of deep space and buzzed the Earth-Moon system, the near-miss would be instant worldwide headline news.

    Two years ago, Earth experienced a close shave just as perilous, but most newspapers didn’t mention it. The “impactor” was an extreme solar storm, the most powerful in as much as 150+ years.

    “If it had hit, we would still be picking up the pieces,” says Daniel Baker of the University of Colorado.

    cme
    Coronal Mass Ejection

    Baker, along with colleagues from NASA and other universities, published a seminal study of the storm in the December 2013 issue of the journal Space Weather. Their paper, entitled A major solar eruptive event in July 2012, describes how a powerful coronal mass ejection (CME) tore through Earth orbit on July 23, 2012. Fortunately Earth wasn’t there. Instead, the storm cloud hit the STEREO-A spacecraft.

    stereo
    STEREO-A spacecraft

    “I have come away from our recent studies more convinced than ever that Earth and its inhabitants were incredibly fortunate that the 2012 eruption happened when it did,” says Baker. “If the eruption had occurred only one week earlier, Earth would have been in the line of fire.

    Extreme solar storms pose a threat to all forms of high-technology. They begin with an explosion–a “solar flare“—in the magnetic canopy of a sunspot. X-rays and extreme UV radiation reach Earth at light speed, ionizing the upper layers of our atmosphere; side-effects of this “solar EMP” include radio blackouts and GPS navigation errors. Minutes to hours later, the energetic particles arrive. Moving only slightly slower than light itself, electrons and protons accelerated by the blast can electrify satellites and damage their electronics. Then come the CMEs, billion-ton clouds of magnetized plasma that take a day or more to cross the Sun-Earth divide. Analysts believe that a direct hit by an extreme CME such as the one that missed Earth in July 2012 could cause widespread power blackouts, disabling everything that plugs into a wall socket. Most people wouldn’t even be able to flush their toilet because urban water supplies largely rely on electric pumps.

    Before July 2012, when researchers talked about extreme solar storms their touchstone was the iconic Carrington Event of Sept. 1859, named after English astronomer Richard Carrington who actually saw the instigating flare with his own eyes. In the days that followed his observation, a series of powerful CMEs hit Earth head-on with a potency not felt before or since. Intense geomagnetic storms ignited Northern Lights as far south as Cuba and caused global telegraph lines to spark, setting fire to some telegraph offices and thus disabling the ‘Victorian Internet.”

    A similar storm today could have a catastrophic effect. According to a study by the National Academy of Sciences, the total economic impact could exceed $2 trillion or 20 times greater than the costs of a Hurricane Katrina. Multi-ton transformers damaged by such a storm might take years to repair.

    “In my view the July 2012 storm was in all respects at least as strong as the 1859 Carrington event,” says Baker. “The only difference is, it missed.”

    In February 2014, physicist Pete Riley of Predictive Science Inc. published a paper in Space Weather entitled On the probability of occurrence of extreme space weather events. In it, he analyzed records of solar storms going back 50+ years. By extrapolating the frequency of ordinary storms to the extreme, he calculated the odds that a Carrington-class storm would hit Earth in the next ten years.

    The answer: 12%.

    “Initially, I was quite surprised that the odds were so high, but the statistics appear to be correct,” says Riley. “It is a sobering figure.”

    In his study, Riley looked carefully at a parameter called Dst, short for “disturbance – storm time.” This is a number calculated from magnetometer readings around the equator. Essentially, it measures how hard Earth’s magnetic field shakes when a CME hits. The more negative Dst becomes, the worse the storm. Ordinary geomagnetic storms, which produce Northern Lights around the Arctic Circle, but otherwise do no harm, register Dst=-50 nT (nanoTesla). The worst geomagnetic storm of the Space Age, which knocked out power across Quebec in March 1989, registered Dst=-600 nT. Modern estimates of Dst for the Carrington Event itself range from -800 nT to a staggering -1750 nT.

    In their Dec. 2013 paper, Baker et al. estimated Dst for the July 2012 storm. “If that CME had hit Earth, the resulting geomagnetic storm would have registered a Dst of -1200, comparable to the Carrington Event and twice as bad as the March 1989 Quebec blackout.”

    The reason researchers know so much about the July 2012 storm is because, out of all the spacecraft in the solar system it could have hit, it did hit a solar observatory. STEREO-A is almost ideally equipped to measure the parameters of such an event.

    “The rich data set obtained by STEREO far exceeded the relatively meagre observations that Carrington was able to make in the 19th century,” notes Riley. “Thanks to STEREO-A we know a lot of about the magnetic structure of the CME, the kind of shock waves and energetic particles it produced, and perhaps most importantly of all, the number of CMEs that preceded it.”

    It turns out that the active region responsible for producing the July 2012 storm didn’t launch just one CME into space, but many. Some of those CMEs “plowed the road” for the superstorm.

    A paper in the March 2014 edition of Nature Communications by UC Berkeley space physicist Janet G. Luhmann and former postdoc Ying D. Liu describes the process: The July 23rd CME was actually two CMEs separated by only 10 to 15 minutes. This double-CME traveled through a region of space that had been cleared out by yet another CME four days earlier. As a result, the storm clouds were not decelerated as much as usual by their transit through the interplanetary medium.

    “It’s likely that the Carrington event was also associated with multiple eruptions, and this may turn out to be a key requirement for extreme events,” notes Riley. “In fact, it seems that extreme events may require an ideal combination of a number of key features to produce the ‘perfect solar storm.'”

    “Pre-conditioning by multiple CMEs appears to be very important,” agrees Baker.

    A common question about this event is, how did the STEREO-A probe survive? After all, Carrington-class storms are supposed to be mortally dangerous to spacecraft and satellites. Yet STEREO-A not only rode out the storm, but also continued taking high-quality data throughout.

    “Spacecraft such as the STEREO twins and the Solar and Heliospheric Observatory (a joint ESA/NASA mission) were designed to operate in the environment outside the Earth’s magnetosphere, and that includes even quite intense, CME-related shocks,” says Joe Gurman, the STEREO project scientist at the Goddard Space Flight Center. “To my knowledge, nothing serious happened to the spacecraft.”

    The story might have been different, he says, if STEREO-A were orbiting Earth instead of traveling through interplanetary space.

    “Inside Earth’s magnetosphere, strong electric currents can be generated by a CME strike,” he explains. “Out in interplanetary space, however, the ambient magnetic field is much weaker and so those dangerous currents are missing.” In short, STEREO-A was in a good place to ride out the storm.

    “Without the kind of coverage afforded by the STEREO mission, we as a society might have been blissfully ignorant of this remarkable solar storm,” notes Baker. “How many others of this scale have just happened to miss Earth and our space detection systems? This is a pressing question that needs answers.”

    If Riley’s work holds true, there is a 12% chance we will learn a lot more about extreme solar storms in the next 10 years—when one actually strikes Earth.

    Says Baker, “we need to be prepared.”

    See the full article, with video, here.

    NASA leads the nation on a great journey of discovery, seeking new knowledge and understanding of our planet Earth, our Sun and solar system, and the universe out to its farthest reaches and back to its earliest moments of existence. NASA’s Science Mission Directorate (SMD) and the nation’s science community use space observatories to conduct scientific studies of the Earth from space to visit and return samples from other bodies in the solar system, and to peer out into our Galaxy and beyond. NASA’s science program seeks answers to profound questions that touch us all:

    This is NASA’s science vision: using the vantage point of space to achieve with the science community and our partners a deep scientific understanding of our planet, other planets and solar system bodies, the interplanetary environment, the Sun and its effects on the solar system, and the universe beyond. In so doing, we lay the intellectual foundation for the robotic and human expeditions of the future while meeting today’s needs for scientific information to address national concerns, such as climate change and space weather. At every step we share the journey of scientific exploration with the public and partner with others to substantially improve science, technology, engineering and mathematics (STEM) education nationwide.

    NASA


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  • richardmitnick 8:24 am on July 11, 2014 Permalink | Reply
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    From NASA Science: “Three Supermoons in a Row “ 

    NASA Science Science News

    NASA Science News

    July 10, 2014
    Dr. Tony Phillips

    In June of last year, a full Moon made headlines. The news media called it a “supermoon” because it was 14% bigger and 30% brighter than other full Moons of 2013. Around the world, people went outside to marvel at its luminosity.

    If you thought one supermoon was bright, how about three….? The full Moons of summer 2014—July 12th, August 10th, and Sept. 9th–will all be supermoons.

    supermoon

    The scientific term for the phenomenon is “perigee moon.” Full Moons vary in size because of the oval shape of the Moon’s orbit. The Moon follows an elliptical path around Earth with one side (“perigee”) about 50,000 km closer than the other (“apogee”). Full Moons that occur on the perigee side of the Moon’s orbit seem extra big and bright.

    This coincidence happens three times in 2014. On July 12th and Sept 9th the Moon becomes full on the same day as perigee. On August 10th it becomes full during the same hour as perigee—arguably making it an extra-super Moon.”

    It might seem that such a sequence must be rare. Not so, says Geoff Chester of the US Naval Observatory.

    “Generally speaking, full Moons occur near perigee every 13 months and 18 days, so it’s not all that unusual,” he says. “In fact, just last year there were three perigee Moons in a row, but only one was widely reported.”

    In practice, it’s not always easy to tell the difference between a supermoon and an ordinary full Moon. A 30% difference in brightness can easily be masked by clouds and haze. Also, there are no rulers floating in the sky to measure lunar diameters. Hanging high overhead with no reference points to provide a sense of scale, one full Moon looks about the same size as any other.

    Chester expects most reports of giant Moons this summer to be … illusory.
    image

    1&2
    Perigee is the point in the Moon’s elliptical orbit closest to Earth. Diagrams:#1, #2

    “The ‘Moon Illusion’ is probably what will make people remember this coming set of Full Moons, more than the actual view of the Moon itself,” he says.

    The illusion occurs when the Moon is near the horizon. For reasons not fully understood by astronomers or psychologists, low-hanging Moons look unnaturally large when they beam through trees, buildings and other foreground objects. When the Moon illusion amplifies a perigee Moon, the swollen orb rising in the east at sunset can seem super indeed.

    “I guarantee that some folks will think it’s the biggest Moon they’ve ever seen if they catch it rising over a distant horizon, because the media will have told them to pay attention to this particular one,” says Chester.

    “There’s a part of me that wishes that this ‘super-Moon’ moniker would just dry up and blow away, like the ‘Blood-Moon’ that accompanied the most recent lunar eclipse, because it tends to promulgate a lot of mis-information,” admits Chester. “However, if it gets people out and looking at the night sky and maybe hooks them into astronomy, then it’s a good thing.”

    Indeed it is.

    See the full article here.

    NASA leads the nation on a great journey of discovery, seeking new knowledge and understanding of our planet Earth, our Sun and solar system, and the universe out to its farthest reaches and back to its earliest moments of existence. NASA’s Science Mission Directorate (SMD) and the nation’s science community use space observatories to conduct scientific studies of the Earth from space to visit and return samples from other bodies in the solar system, and to peer out into our Galaxy and beyond. NASA’s science program seeks answers to profound questions that touch us all:

    This is NASA’s science vision: using the vantage point of space to achieve with the science community and our partners a deep scientific understanding of our planet, other planets and solar system bodies, the interplanetary environment, the Sun and its effects on the solar system, and the universe beyond. In so doing, we lay the intellectual foundation for the robotic and human expeditions of the future while meeting today’s needs for scientific information to address national concerns, such as climate change and space weather. At every step we share the journey of scientific exploration with the public and partner with others to substantially improve science, technology, engineering and mathematics (STEM) education nationwide.

    NASA


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  • richardmitnick 4:19 pm on November 25, 2013 Permalink | Reply
    Tags: , , , , NASA Science News   

    From NASA Science News: “Comet ISON vs. the Solar Storm” 

    NASA Science Science News

    Nov. 24, 2013

    Credits: Author: Dr. Tony Phillips | Production editor: Dr. Tony Phillips | Credit: Science@NASA

    In 2007, astronomers were amazed when a solar storm hit Comet Encke. NASA STEREO spacecraft watched as a CME (coronal mass ejection) struck the comet head on and ripped off its tail.

    The same thing could be in store for Comet ISON–only worse.

    ison
    ISON’s path

    dt
    ISON’s double tail

    On Nov. 28th, Comet ISON will pass through the sun’s atmosphere, flying little more than a million kilometers above the sun’s surface. It will be ~30 times closer to the sun than Encke was in 2007 and more likely to encounter a ferocious solar storm.

    “For one thing,” says Angelos Vourlidas of the Naval Research Lab and a participant in NASA’s Comet ISON Observing Campaign (CIOC), “the year 2007 was near solar minimum. Solar activity was low. Now, however, we are near the peak of the solar cycle and eruptions are more frequent.”

    “I would absolutely love to see Comet ISON get hit by a big CME,” says Karl Battams, an astronomer at the Naval Research Lab who also works with the CIOC. “It won’t hurt the comet, but it would give us a chance to study extreme interactions with the comet’s tail.”

    CMEs are magnetized clouds of plasma hurled into space by the explosions of sunspots. The gas inside a CME is not very dense, so its impact would not shatter a comet’s core. The fragile tail is another matter. Comet tails are as gossamer as the CMEs themselves, so the interactions can be intense and unpredictable.

    “The CME that ran over Comet Encke back in 2007 was slow, barely creating a pressure pulse by compressing the solar wind ahead of it,” notes Vourlidas. “It was this compression which caused the Encke’s tail to fly off.”

    He believes that Comet ISON would experience something more dramatic. “Any CME that hits Comet ISON close to the sun would very likely be faster, driving a shock wave with a much stronger magnetic field. Frankly, we can’t predict what would happen.”

    Comet ISON entered the field of view of STEREO-A’s Heliospheric Imager on Nov. 21st. Coincidentally, Comet Encke is there, too. Presently, the two comets are being gently buffeted by solar wind and their tails are wagging back and forth accordingly.

    If the sun erupts, both comets could be engulfed by the same CME. This would turn the two comets into solar probes. Like wind socks, they would sample the storm from two widely separated locations, giving researchers a rare 3D view of a CME’s inner structure.

    Comet ISON will be passing over the sun’s equator on Nov. 28th on the same side of the sun where a group of active sunspots was recently clustered. In other words, says Battams, “we’re going to be in the ‘hot zone’ for CMEs.”

    NASA’s entire fleet of solar observatories will be watching when ISON takes the plunge. This includes STEREO-A and STEREO-B, the Solar Dynamics Observatory, and the Solar and Heliophysics Observatory (SOHO), which NASA operates along with the European Space Agency. If a CME strikes the comet, all of the spacecraft are likely to see what happens.

    “It would be pretty new territory for us,” says Battams.

    “…and a nice preview of what NASA’s Solar Probe+ spacecraft might experience when it plunges into the sun in the 2020s,” adds Vourlidas.

    Stay tuned!

    See the full article, with videos, here.

    NASA leads the nation on a great journey of discovery, seeking new knowledge and understanding of our planet Earth, our Sun and solar system, and the universe out to its farthest reaches and back to its earliest moments of existence. NASA’s Science Mission Directorate (SMD) and the nation’s science community use space observatories to conduct scientific studies of the Earth from space to visit and return samples from other bodies in the solar system, and to peer out into our Galaxy and beyond. NASA’s science program seeks answers to profound questions that touch us all:

    This is NASA’s science vision: using the vantage point of space to achieve with the science community and our partners a deep scientific understanding of our planet, other planets and solar system bodies, the interplanetary environment, the Sun and its effects on the solar system, and the universe beyond. In so doing, we lay the intellectual foundation for the robotic and human expeditions of the future while meeting today’s needs for scientific information to address national concerns, such as climate change and space weather. At every step we share the journey of scientific exploration with the public and partner with others to substantially improve science, technology, engineering and mathematics (STEM) education nationwide.

    NASA


    ScienceSprings is powered by MAINGEAR computers

     
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