Astronomy

How well can the Sun's surface be resolved by an observatory?

How well can the Sun's surface be resolved by an observatory?


We are searching data for your request:

Forums and discussions:
Manuals and reference books:
Data from registers:
Wait the end of the search in all databases.
Upon completion, a link will appear to access the found materials.

There's no lack of photons, how well could a telescope resolve Sun spots and other surface features of the Sun? How would a high resolution Solar (space) telescope differ from for example Hubble which avoids the Sun by a 50° angle or so?


Solar telescopes typically have filters to reduce the amount of light reaching their detector. Depending on their purpose they may use, for example, neutral density filters to reduce the amount of light to a level where they can resolve details without blocking any of the visible spectrum, hydrogen alpha filters to observe the Sun at a wavelength of 656 nanometres for observing features in the Sun's atmosphere such as solar prominences and the chromosphere, or blocking the solar disc to observe the Sun's corona, flares and other ejecta.

Hubble, on the other hand, is designed with a very different purpose in mind such as taking long-exposure images to obtain the deep- and ultra-deep field full spectrum images. It avoids the Sun as even a very short exposure to the Sun would damage its instruments.


Space Science

During this first complete operational year of NASA's refurbished Hubble Space Telescope (HST), astronomers made many dramatic discoveries stretching to the edge of the universe from neighboring planets in our solar system. (HST was launched in April 1990 and serviced in December 1993.) HST continues to be one of the most widely used observatories in history, as at least 60 percent of all astronomers in the United States are HST investigators who work through the Space Telescope Science Institute to accomplish their observations.

A team that included scientists from the Smithsonian Astrophysical Observatory (SAO) and other institutions used HST to derive a new, higher value for the universe's expansion rate, thus implying an unexpectedly young age for the universe. By accurately determining the distance to a galaxy in the Virgo cluster and calculating for the local effects of the universe's expansion rate, scientists were able to make this precise measurement. Astronomers determined that the universe is smaller and younger than previously thought, about 10 billion years old—only twice the age of the planet Earth.

Another team used HST to gather evidence that the clouds of hydrogen gas found between galaxies at distances of billions of light-years from Earth are at least 1 million light-years in diameter, or about 10 times larger than previously thought, and may have a remarkable sheet-like structure. These results shed new light on the properties of hydrogen gas clouds, whose nature has been a mystery since their discovery a quarter of a century ago, and may provide clues to understanding the evolution of galaxies in the early universe.

HST observations by SAO astronomers of faint stars deep inside a globular cluster provided strong evidence for the existence of cataclysmic variables. These are violently interacting double-star systems that may hold clues to the evolution of the clusters, which contain some of the oldest stars in the universe.

HST images of the most distant galaxies yet seen also showed how the structure of galaxies evolved over most of the history of the universe. Dramatically detailed images of energetic stars in our own galaxy showed the process whereby material is ejected from new stars in one direction while disks of dust, similar in size to our solar system, accumulate around the star. Scientists from the National Institute of Standards and Technology (NIST) calibrated benchmark oscillator strengths for a number of atoms calculated from the state-of-the-art atomic structure theory this helped NASA judge the reliability of atomic data against the high accuracy of observed data such as that from HST.

In other astronomical news, the Astro-2 observatory achieved exceptional results with three telescopes observing ultraviolet light in a record-setting 16-day flight on the Space Shuttle Endeavour in March 1995. The most important result was a definitive measurement of the amount of helium spread throughout intergalactic space, measured to be the amount predicted by the Big Bang hypothesis. This states that the element helium was created during a hot phase of the primordial universe, only a few minutes after the Big Bang itself. The Astro-2 mission was also the first Shuttle mission with live Internet access, with more than 2 million requests logged in for mission information.

The Compton Gamma Ray Observatory (CGRO), launched in April 1991, continued a variety of observations of gamma rays, the most energetic form of light. By the end of FY 1995, scientists had recorded more than 1,400 of the mysterious gamma ray bursts, spread evenly over the entire sky. CGRO gives astrophysicists their only tool for continuing observations of this most dramatic celestial mystery. Scientists do not know whether these gamma ray explosions, lasting a few seconds, come from mysterious objects surrounding our own galaxy or whether they arise in other galaxies near the outer edges of the universe. A public debate by astrophysicists did not resolve the question. CGRO also completed a new survey of the highest energy gamma ray sources, demonstrating that about half of them are quasars with beams of energy pointed directly toward us but leaving the other half as yet unidentified.

Following CGRO and HST, the next Great Observatory will be the Advanced X-Ray Astrophysics Facility (AXAF). Figuring and polishing of the eight x-ray reflecting mirrors for AXAF were completed during FY 1995, in preparation for mirror coating. These are by far the most precise optics ever developed for imaging x-rays, and the completed mirrors significantly exceed performance requirements. In addition, the high-resolution camera being constructed at the SAO passed its critical design review.

The Ulysses spacecraft, launched in October 1990, successfully completed its passage over the northern pole of the Sun, completing the first ever exploration of the solar wind above its polar regions. Ulysses is now moving away from the Sun and will return again to pass over the Sun's poles in the years 2000 and 2001. The polar passages occurred during solar minimum, when activity on the Sun is at its lowest and when the polar regions are dominated by high-speed solar wind flows. Ulysses found that the solar wind was dominated by high-speed flow for latitudes above about 30 degrees north or south. Scientists working on the Ulysses and Voyager spacecraft projects detected oscillations in solar wind measurements, providing clues about the deep interior of the Sun. SPARTAN 201, a small satellite deployed and retrieved by the Space Shuttle in September 1994 and September 1995 during the polar passages by Ulysses, discovered the presence of unexpectedly hot (about 10 million degrees Centigrade) gas above the Sun's poles. This may explain why the solar wind speed is so high (500 miles per second) in the solar polar regions.

Voyagers 1 and 2, launched in 1977, and Pioneers 10 and 11, launched in 1972 and 1973, respectively, continued their exploration of the outer frontiers of the solar system. Now nearly twice as far from the Sun as Pluto, these spacecraft are approaching the boundary between the solar system and interstellar space. The Voyagers, which have sufficient power reserves to operate until 2015, could reach that boundary by the end of this century and become the first interstellar probes.

NASA was also active in several international programs devoted to space physics research. Yohkoh, a joint Japanese/U.S. mission launched in August 1991, continued its measurements of the solar corona and observation of the change in its x-ray brightness, activity, and structural complexity as it evolves from solar maximum to solar minimum. In November 1994, the Global Geospace Science (GGS) Wind spacecraft was launched successfully into a path upstream of the Earth's magnetosphere, where it has been providing information on the solar wind that determines conditions in the magnetosphere, including the downstream tail region. The Geotail spacecraft discovered particles from the Earth's ionosphere in the distant magnetic tail region at distances (210 Earth radii) beyond that of the Moon. Yohkoh, Wind, and Geotail are key elements of the International Solar-Terrestrial Physics (ISTP) Program for studying solar variability and its effects on the near-Earth space environment. This program involves spacecraft from the United States, Japan, Europe, and Russia. Several other ISTP spacecraft were scheduled to be launched by 1996.

In the suborbital area, NASA scientists made new discoveries about upper atmospheric flashes during aircraft and ground campaigns. These flashes, called sprites (red flashes) and jets (blue fountains), appear over intense thunderstorms and extend as high as 60 miles into the ionosphere. Scientists obtained the first spectra of a sprite in summer 1995 and also obtained high-resolution images showing a new type of sprite and its complex structuring. Another flight campaign over intense thunderstorms in Central America detected far fewer events than were seen over similarly intense storms over the Great Plains last year. Scientists believe that the study of these dramatic upper atmospheric flashes, and the thunderstorms with which they are associated, can lead to increases in airplane safety. In another element of the suborbital program, NASA's sounding rocket program had 30 consecutive launch successes in FY 1995.

NASA's Solar, Anomalous, and Magnetospheric Particle Explorer (SAMPEX) spacecraft continued its study of the energetic electrons and atomic ions from the Sun, as well as interplanetary, interstellar, and magnetospheric space. SAMPEX data are providing critical insights into how cosmic rays are accelerated out at the heliospheric shock, caused by the collision of the solar wind with the interstellar gas. SAMPEX measurements have provided data on energetic particles in the trapped radiation belts, which can affect electronic systems in spacecraft such as communication satellites.

Using the Very Long Baseline Array (VLBA) of the National Science Foundation (NSF), a team of scientists from the SAO and Japan were able to show compelling evidence for the existence of a black hole in the center of the galaxy NGC 4258. The latest telescope of the NSF-sponsored National Radio Astronomy Observatory, the VLBA's 10 antennas simulate the magnifying power of a radio telescope more than 5,000 miles in diameter. Astronomers from Japan's National Astronomical Observatory and the Harvard-Smithsonian Center for Astrophysics pointed the VLBA to the center of NGC 4258 to make images of such high resolution that the individual positions of water vapor masers could be measured as well as the speed of their motion along the line of sight to the galaxy. This is equivalent to reading a sign on a truck in Los Angeles from New York and measuring the speed of the truck as well. A simple calculation yielded the mass of the central object, 30 million solar masses, much too large a mass to be contained in the available volume except by a black hole. The massive black hole in the center of NGC 4258 has presumably grown to its huge size through years of accretion of matter in the densely populated region of the galaxy's center.

Astronomers at the NSF-sponsored Kitt Peak National Observatory investigated the formation of the Milky Way galaxy's Galactic Halo, an enigmatic distribution of older stars that appears key to understanding the formation of our galaxy. The challenge in studying the Halo came in isolating a sample of stars guaranteed to be members of that population. The team of astronomers was surprised to observe that the flattened population of "young" stars seems to be older than the spherical population of "old" stars. Was this subsystem of galactic stars formed during the collapse of the protogalaxy from an initial spherical distribution of gas, or was it formed by the aggregation of smaller dwarf galaxies trapped in the gravitational field of the larger Milky Way? One explanation is that both scenarios for formation of the Milky Way contributed, with the flatter distribution of stars coming from the collapse phase of the proto-galaxy and the younger spherical population resulting from the capture and shredding of neighboring dwarf galaxies. This challenging topic remained the focus of intense observational effort.

Scientists used the NSF-sponsored Cerro-Tololo Inter-American Observatory's Blanco Telescope to observe and analyze the Magellanic Stream, a large filament of neutral hydrogen gas from the Milky Way's radio emission that originates at the Small Magellanic Cloud (a Milky Way satellite dwarf galaxy) and extends almost one-third of the way around the sky. The astronomical team discovered unexpectedly strong optical line emission from hydrogen at the leading edge of the stream, where the density of neutral hydrogen detected in radio increases steeply. What is the source of this energetic emission? The association with the cloud's leading edges suggests that as the stream moves through high-pressure, low-density gas, shock waves propagating into the gas of the stream produce this emission. While radio, optical, and x-ray observations have long shown that there is diffuse gas associated with the Milky Way up to 150,000 light-years away from our galaxy, the origin and distribution of this hot gas remained controversial.

Astronomers at the NSF-sponsored vacuum tower telescope on Sacramento Peak used a new technique called phase-diverse speckle imaging to take time-series images of hot gaseous bubbles rising to the surface of the Sun. The resulting time series of a magnetic region without sunspots showed the highly dynamic visible layer of the solar atmosphere at scales of less than 200 kilometers. This new imaging technique depicted the detailed evolution of the bright edges of granules (the convective cells on the solar surface) for the first time. Scientists hoped that further study of these granules will yield useful information about the hot gaseous layers of chromosphere and corona above the Sun's surface.

The Center for Astrophysical Research in Antarctica (CARA), one of NSF's 25 Science and Technology Centers, completed its second year of year-round operations. The cold dry atmosphere and lack of diurnal variation make the South Pole the best site on Earth for many radio and infrared measurements. Site measurements by the South Pole InfraRed Explorer telescope have now indicated that the sky at the South Pole is darker by a factor of at least 20 than any other site previously surveyed. PYTHON, one of two telescopes comprising the Cosmic Background Radiation Anisotrophy, made measurements at the South Pole during the past two austral summers and operated for the first time during the winter. PYTHON confirmed the Cosmic Microwave Background (CMB) anisotropy, first measured by the Cosmic Background Explorer (COBE) satellite, and began to make a finer scale map of the CMB than COBE could. The 1.7-meter Antarctic Submillimeter Telescope and Remote Observatory, built by the SAO, was installed at the South Pole during the austral summer of 1994-1995. It quickly produced more than 10,000 spectra of neutral carbon lines in the galaxy and the Large Magellanic Cloud and also made measurements of atmospheric trace gases, such as ozone and carbon monoxide. Australian and NASA investigators working with CARA have undertaken a survey of the South Pole atmospheric transparency in the mid-infrared (5 to 40 millimeters). Measurements made during the 1994-1995 summer were encouraging enough for Goddard Space Flight Center (GSFC) scientists to propose that monitoring equipment be wintered during 1996.

During the austral summer of 1994-1995 in Antarctica, NSF deployed a new Automatic Geophysical Observatory (AGO), bringing to four the number now operating in the field. The AGO's, which were built by Lockheed, provide heat, power, and data storage for a suite of several remote-sensing instruments for years of unattended operation. When all the AGO's are deployed, they will provide, in conjunction with a few manned stations, uninterrupted and overlapping observations of the very high magnetic latitude ionosphere with a number of instruments. Following the lead of NSF, the British and Japanese Antarctic programs began developing their own AGO's, which will provide additional data in the lower latitude auroral zone. The AGO network will complement significantly the ISTP Program, especially the NASA Polar satellite.

Also during the austral summer of 1994-1995, NASA and NSF continued their joint program of long-duration ballooning in Antarctica. NASA launched two joint payloads during FY 1995— one carried emulsion track chambers to study the composition of heavy cosmic ray particles, and the second payload was a very large, high-energy gamma ray detector. Both payloads were recovered after flights of more than 10 days.

A scientist at the Laboratory for Astrophysics at the National Air and Space Museum (part of the Smithsonian Institution) in Washington, DC detected the first "natural" laser in space. Aboard NASA's Kuiper Airborne Observatory (KAO), the scientist used the aircraft's infrared telescope to observe a young, very hot, luminous star in the constellation Cygnus. Such lasers are created as intense ultraviolet light from the star "pumps," or excites, densely packed hydrogen atoms in the gaseous, dusty disk surrounding a young star, causing the atoms to emit an intense beam of infrared light. The discovery of this naturally occurring laser has given astronomers a powerful tool for probing the conditions in circumstellar disks where planets are thought to form.


Active stars

Artist's conception of a stellar flare as seen from the planet Proxima Centauri b, a potentially Earth-like world. (Credit: NRAO/S. Dagnello)

The star has long been a target for scientists hoping to find life beyond Earth’s solar system. Proxima Centauri is nearby, for a start. It also hosts one planet, designated Proxima Centauri b, that resides in what researchers call the “habitable zone”—a region around a star that has the right range of temperatures for harboring liquid water on the surface of a planet.

But there’s a twist, MacGregor said: Red dwarves, which rank as the most common stars in the galaxy, are also unusually lively.

“A lot of the exoplanets that we’ve found so far are around these types of stars,” she said. “But the catch is that they’re way more active than our sun. They flare much more frequently and intensely.”

To see just how much Proxima Centauri flares, she and her colleagues pulled off what approaches a coup in the field of astrophysics: They pointed nine different instruments at the star for 40 hours over the course of several months in 2019. Those eyes included the Hubble Space Telescope, the Atacama Large Millimeter Array (ALMA) and NASA’s Transiting Exoplanet Survey Satellite (TESS). Five of them recorded the massive flare from Proxima Centauri, capturing the event as it produced a wide spectrum of radiation.

“It’s the first time we’ve ever had this kind of multi-wavelength coverage of a stellar flare,” MacGregor. “Usually, you’re lucky if you can get two instruments.”


How well can the Sun's surface be resolved by an observatory? - Astronomy

The National Science Foundation has just released the very first images of the Sun taken with the new Inouye Solar Telescope in Hawaii. They are the highest resolution images ever taken of the Sun&rsquos surface, showing three times more detail than was possible using previous imaging techniques. Those cells you see in the image&hellipthey&rsquore each about the size of Texas.

Building a telescope like this is not an easy task &mdash there&rsquos a lot of heat to deal with:

To achieve the proposed science, this telescope required important new approaches to its construction and engineering. Built by NSF&rsquos National Solar Observatory and managed by AURA, the Inouye Solar Telescope combines a 13-foot (4-meter) mirror &mdash the world&rsquos largest for a solar telescope &mdash with unparalleled viewing conditions at the 10,000-foot Haleakala summit.

Focusing 13 kilowatts of solar power generates enormous amounts of heat &mdash heat that must be contained or removed. A specialized cooling system provides crucial heat protection for the telescope and its optics. More than seven miles of piping distribute coolant throughout the observatory, partially chilled by ice created on site during the night.

Scientists have released a pair of mesmerizing time lapse videos as well, showing ten minutes of the roiling surface of the Sun (wide angle followed by a close-up view) in just a few seconds:

The Daniel K. Inouye Solar Telescope has produced the highest resolution observations of the Sun&rsquos surface ever taken. In this movie, taken at a wavelength of 705nm over a period of 10 minutes, we can see features as small as 30km (18 miles) in size for the first time ever. The movie shows the turbulent, &ldquoboiling&rdquo gas that covers the entire sun. The cell-like structures &mdash each about the size of Texas &mdash are the signature of violent motions that transport heat from the inside of the sun to its surface. Hot solar material (plasma) rises in the bright centers of &ldquocells,&rdquo cools off and then sinks below the surface in dark lanes in a process known as convection. In these dark lanes we can also see the tiny, bright markers of magnetic fields. Never before seen to this clarity, these bright specks are thought to channel energy up into the outer layers of the solar atmosphere called the corona. These bright spots may be at the core of why the solar corona is more than a million degrees!

Man, I hope we get some longer versions of these time lapses &mdash I would watch the hell out of one that ran for 10 minutes. (via moss & fog)


World's largest solar observatory releases first image of a sunspot

Dec. 4 (UPI) -- The Daniel K. Inouye Solar Telescope, DKIST, the world's largest solar observatory, has released its first portrait of a sunspot. The photograph's impressive details highlight the optical powers of the Hawaiian observatory.

Researchers released the image in conjunction with a new paper -- published Friday in the journal Solar Physics -- describing the telescope's mechanical features, optical instruments and scientific objectives.

Sunspots are dark spots found on the surface of the sun created by magnetic field flux, where the convergence of magnetic fields stunts convection and cools the sun's surface.

In the new image, hot and cool gas can be seen spidering outward from the sunspot's edge. The radiating pattern is created when rising hot gas and sinking cool gas become stretched along the lines of the inclined magnetic field.

Solar activity rises and falls over the course of an 11-year solar cycle. When solar activity is greatest, the surface of the sun is dotted with more sunspots.

DKIST snapped the portrait in January of this year, shortly after the sun reached its solar minimum at the end of 2019.

The sunspot imaged by the Inouye Solar Telescope was one of the first of the new solar cycle. It measured more than 10,000 miles wide.

Scientists expect the sun to reach its solar maximum in the middle of 2025.

"With this solar cycle just beginning, we also enter the era of the Inouye Solar Telescope," Matt Mountain, president of the Association of Universities for Research in Astronomy, which manages the National Solar Observatory and the Inouye Solar Telescope, said in a news release.

"We can now point the world's most advanced solar telescope at the sun to capture and share incredibly detailed images and add to our scientific insights about the sun's activity," said Mountain.

Sunspots aren't just optical phenomenon. The majority of solar flares and coronal mass ejections originate from the hyper-magnetized regions surrounding sunspots.

Scientists expect DKIST to provide new insights into the mechanics of supports and their related phenomena -- insights that will help researchers more accurately predict the trajectory of solar storms, which can disrupt communications systems and power grids, as well as put astronauts at risk.

"While the start of telescope operations has been slightly delayed due to the impacts of the COVID-19 global pandemic, this image represents an early preview of the unprecedented capabilities that the facility will bring to bear on our understanding of the sun," said David Boboltz, program director for the Inouye Solar Telescope at the National Science Foundation.

DKIST is funded by NSF and managed by the National Solar Observatory through a cooperative agreement with the Association of Universities for Research in Astronomy.


The Telescopes and Science

From its establishment in 1966 as the Smithsonian Mount Hopkins Observatory, FLWO has hosted a world-class suite of telescopes designed for a wide variety of purposes.

The largest visible-light telescope ​at FLWO is the MMT Observatory, which has a primary mirror 6.5 meters (21 feet) in diameter. Jointly operated by the Smithsonian and the University of Arizona, the MMT is located at the summit of Mt. Hopkins. The MMT was originally designed as the Multiple Mirror Telescope in 1979, consisting of six individual mirrors working together. With improved mirror technology, the smaller mirrors were replaced by the current large mirror in 2000, though the observatory kept the name “MMT”. In 2002, the observatory implemented “adaptive optics”, which uses a secondary mirror. The shape of this mirror can be changed to correct for distortions in Earth’s atmosphere, providing the sharpest images in astronomy. The MMT also includes spectroscopic instruments to identify atomic emission and other observations where precise light wavelength measurements are important.

CfA’s gamma-ray observatory VERITAS is located at the base of Mt. Hopkins, and consists of an array of four 12-meter telescopes. Earth’s atmosphere blocks gamma rays from reaching the ground, but in the process, the high-energy light creates a flash of blue light known as Cherenkov radiation. The VERITAS telescopes work together to observe the blue light, characterizing the sources of some of the highest energy light known: supermassive black holes and other extreme environments in the universe.

In addition to the MMT, the FLWO has two smaller general-purpose visible-light telescopes: the FLWO 1.2-meter imaging optical telescope and the 1.5-meter Tillinghast optical spectroscopic telescope. These telescopes are used in observing objects in the Solar System, as well as a wide variety of astronomical observations in the Milky Way and beyond.

FLWO is host to two Smithsonian computer-controlled automatic observatories — also known as robotic observatories — designed to look for potentially habitable planets: the MINiature Exoplanet Radial Velocity Array (MINERVA) and the MEarth Project. MINERVA consists of four 70-cm optical telescopes, which look for the large rocky planets known as super-Earths in orbit around Sun-like stars. The MEarth array of eight 40-cm optical telescopes is designed to find Earth-like worlds orbiting the small red stars called “M dwarfs”, which is the source of the “M” in the name.

The HATNet (Hungarian-made Automated Telescope Network) is an array of five robotic optical telescopes, currently operated by Princeton University. Along with two other telescopes located on Mauna Kea in Hawaii, these five instruments are designed to detect transits: the brief reduction in a star’s light when an orbiting exoplanet passes in front of it. To date, astronomers have used HAT to detect over 60 exoplanets.

The FLWO is also host to The Tierras Observatory, an upcoming fully-automated photometer capable of measuring the transit of Earth-sized planets orbiting M Dwarf stars with hitherto unachievable precision from the ground. Tierras will repurpose the dormant 1.3m telescope, which hosted the 2MASS (North) infrared camera over a decade ago.


When the Sun Went Medieval on Our Planet

In the years 774 and 993, the Earth was attacked from space.

Not by aliens, but by a natural event—and it was very, very powerful.

Whatever it was, it subtly altered the chemistry of our planet’s atmosphere, creating trace amounts of radioactive elements like chlorine-36, beryllium-10, and carbon-14. And those provide the clue to what the event was: Those isotopes are created when high-energy protons slam into our air. That means the source must have been from space.

These must have been huge waves of subatomic particles that slammed into us on those dates. Spikes in the abundances of those elements were found all over the world, including ice cores from the Arctic and Antarctic, Chinese corals, and more. Generating that many particles isn’t easy, and only extremely violent events can do it.

Several possible sources have been considered. One candidate is that the Earth got caught in the beam from a gamma-ray burst, the mind-crushingly powerful demise of a very high mass star. I wrote about this being the possible cause of the 774 event in an earlier article. However, GRB impacts don’t usually create 10 Be due to the detailed physics of the blast, so that makes a GRB as the source shaky. Plus, they’re very rare events, so having two happen in as many centuries is extremely unlikely (I didn’t know about the 993 event when I wrote that article, or else I would’ve been a lot more likely to wonder about other sources).

The Sun generates ridiculously strong magnetic fields in its interior, and these can store vast amounts of energy. They can release this energy explosively on the surface, creating intense solar flares. Sometimes the loops of magnetism do this far above the Sun’s surface, creating what are called coronal mass ejections. These are less intense (that is, less concentrated bursts of energy) than flares, but far larger and more powerful think of flares versus CMEs like solar tornadoes versus hurricanes.

You can find out more about these events in the Crash Course Astronomy episode I did on the Sun:

I also have a chapter in my book Death From the Skies! about solar storms and their effects on Earth.

When I wrote about the 774 event on this blog before, I mentioned that a flare or coronal mass ejection was unlikely to be the source due to the amount of energy needed to create these radioactive elements. However, that new research indicates that the Sun is the most likely culprit for this interplanetary assault, and that, in turn, means the Sun can produce more powerful events than we previously thought.

Photo by ESA and NASA/SOHO

We’ve known for a long time that the Sun is capable of producing huge magnetic explosions. In 2003 it let rip a series of solar storms so powerful that one of them set the record for the biggest flare seen in modern times. And the strongest known was also the very first solar explosion ever seen—called the Carrington Event, after an astronomer who studied it—and happened in 1859. It created aurora as far south as Mexico and Hawaii! Events like that can also create what are called geomagnetically induced currents, or GICs: The Earth’s magnetic field shakes so violently that it induces currents in conductors on the ground. Telegraph operators reported being able to send messages even though the power was disconnected enough electricity was flowing through the lines to work the devices.

There’s more. In 2012 the Sun blew out another blockbuster that was in many ways the equal of the one in 1859, but happily for us it was sent off in another direction, and missed the Earth. Had it hit us, the huge flux of charged particles would have overloaded satellites. Worse, the GIC would’ve caused widespread power failures and blackouts. A much smaller solar storm in 1989 did just that in Quebec.

It’s not clear whether the 774 and 993 events were that powerful or more it’s hard to scale these things without direct measurements. But the astronomers who did the research estimate the 774 event (the more powerful of the pair) was five times stronger than any solar storm seen in the modern satellite era (starting in 1956) up to 2005.

I’ll admit, that’s scary. Our modern civilization depends on our electronic devices, and those in turn depend on electricity and satellites. A blast hitting the Earth from a storm as big as any of those four historical events would be bad. Very bad. The 1989 power surge blew out huge transformers in North America, and these can take months to replace. Imagine months without electricity, and you start to get an idea of how disastrous this can be.

We don’t know how often the Sun throws a tantrum as large as these, but clearly it’s done so at least four times in the past millennium or so—probably more, since three of them hit the Earth, and we only knew of the fourth due to our space-based astronomical assets. Statistically speaking, most will miss us, so they’re likely more common than we thought.

This is a threat we need to take very seriously. Unfortunately, it’s extremely expensive to mitigate. Our power grid in the U.S. was constructed decades ago when our use of electricity was much lower. It was designed with lots of spare room for more power flowing through it, but over the years our appetite has grown, and the grid is currently very nearly at capacity. Big spikes now can cripple huge areas.

We need to upgrade the grid, add more capacity, more capability to handle surges induced by solar storms. The good news is there are studies being done to see what we can do to prevent widespread blackouts, and NASA is on it as well. We also have eyes on the Sun, including NASA’s Solar Dynamics Observatory, and scientists monitor “space weather” constantly.

By coincidence, just last night I read that the White House is looking into this situation pretty seriously, and I’m very glad to hear it. A monster solar storm may be the biggest and most immediate threat there is from space, but it’s one we can handle if we’re prepared for it.


NASA's Solar Dynamics Observatory catches 'surfer' waves on the sun

Cue the surfing music. Scientists have spotted the iconic surfer's wave rolling through the atmosphere of the sun. This makes for more than just a nice photo-op: the waves hold clues as to how energy moves through that atmosphere, known as the corona.

Since scientists know how these kinds of waves -- initiated by a Kelvin-Helmholtz instability if you're being technical -- disperse energy in the water, they can use this information to better understand the corona. This in turn, may help solve an enduring mystery of why the corona is thousands of times hotter than originally expected.

"One of the biggest questions about the solar corona is the heating mechanism," says solar physicist Leon Ofman of NASA's Goddard Space Flight Center, Greenbelt, Md. and Catholic University, Washington. "The corona is a thousand times hotter than the sun's visible surface, but what heats it up is not well-understood. People have suggested that waves like this might cause turbulence which cause heating, but now we have direct evidence of Kelvin-Helmholtz waves."

Ofman and his Goddard colleague, Barbara Thompson, spotted these waves in images taken on April 8, 2010. These were some of the first images caught on camera by the Solar Dynamics Observatory (SDO), a solar telescope with outstanding resolution that launched on February 11, 2010 and began capturing data on March 24 of that year. The team's results appeared online in Astrophysical Journal Letters on May 19, 2011 and will be published in the journal on June 10.

That these "surfer" waves exist in the sun at all is not necessarily a surprise, since they do appear in so many places in nature including, for example, clouds on Earth and between the bands of Saturn. But observing the sun from almost 93 million miles away means it's not easy to physically see details like this. That's why the resolution available with SDO gets researchers excited.

"The waves we're seeing in these images are so small," says Thompson who in addition to being a co-author on this paper is the deputy project scientist for SDO. "They're only the size of the United States," she laughs.

Kelvin-Helmholtz instabilities occur when two fluids of different densities or different speeds flow by each other. In the case of ocean waves, that's the dense water and the lighter air. As they flow past each other, slight ripples can be quickly amplified into the giant waves loved by surfers. In the case of the solar atmosphere, which is made of a very hot and electrically charged gas called plasma, the two flows come from an expanse of plasma erupting off the sun's surface as it passes by plasma that is not erupting. The difference in flow speeds and densities across this boundary sparks the instability that builds into the waves.

In order to confirm this description, the team developed a computer model to see what takes place in the region. Their model showed that these conditions could indeed lead to giant surfing waves rolling through the corona.

Ofman says that despite the fact that Kelvin-Helmholtz instabilities have been spotted in other places, there was no guarantee they'd be spotted in the sun's corona, which is permeated with magnetic fields. "I wasn't sure that this instability could evolve on the sun, since magnetic fields can have a stabilizing effect," he says. "Now we know that this instability can appear even though the solar plasma is magnetized."

Seeing the big waves suggests they can cascade down to smaller forms of turbulence too. Scientists believe that the friction created by turbulence -- the simple rolling of material over and around itself -- could help add heating energy to the corona. The analogy is the way froth at the top of a surfing wave provides friction that will heat up the wave. (Surfers of course don't ever notice this, as any extra heat quickly dissipates into the rest of the water.)

Hammering out the exact mechanism for heating the corona will continue to intrigue researchers for some time but, says Thompson, SDO's ability to capture images of the entire sun every 12 seconds with such precise detail will be a great boon. "SDO is not the first solar observatory with high enough visual resolution to be able to see something like this," she says. "But for some reason Kelvin-Helmholtz features are rare. The fact that we spotted something so interesting in some of the first images really shows the strength of SDO."


Focus on Betelgeuse

The red supergiant (RSG) phase marks a short-lived period near the end of the lives of massive stars (roughly 8 or more times the mass of the Sun). RSGs are frequently observed to be losing mass at high rates through cool, low-velocity outflows, and this mass loss has a profound effect on the ultimate evolutionary fate of the star—including whether it will ultimately end its life as a supernova. However, the details of the RSG mass-loss process, including its driving mechanism, geometry, and timescale, are poorly understood. One the most significant challenges for understanding mass loss from RSGs is uncovering the mechanism(s) responsible for heating the outer atmosphere, transporting material from the stellar “surface” into the wind, and ultimately sustaining the outflow.

Standing on the shoulder of Orion

Betelgeuse (also known as α Orionis), visible in the “shoulder” of the constellation Orion, is one of the nearest and brightest RSGs, making it one of the largest angular diameter stars in the sky. A consequence is that with current instruments it is now possible to spatially resolve the dynamic surface of Betelgeuse over a wide range of wavelengths—from the ultraviolet to the radio. By combining findings derived from such multiwavelength data, astronomers have the opportunity to glean unprecedented new insights into the structure, atmospheric dynamics, energy balance, and mass-loss process of a RSG.

Motivated by these goals, a consortium of more than 20 researchers from around the world (coordinated by Andrea Dupree, Center for Astrophysics | Harvard & Smithsonian) is undertaking an ambitious multi-year program know as the “Months of Betelgeuse (MOB).” MOB members are orchestrating an intensive campaign of multiwavelength observations of Betelgeuse from the ground and space. Haystack researcher Lynn Matthews is leading a component of this program that involves high-resolution radio imaging observations of Betelgeuse using the Karl G. Jansky Very Large Array (VLA) and the Atacama Large Millimeter/submillimeter Array (ALMA).


Scientists have found the Eye of Sauron . on the Sun

The image reveals new details about the mysterious solar cycle.

The most detailed image of a sunspot ever recorded was sort of random.

On January 28, 2020, the National Science Foundation pointed its telescope toward the Sun while its systems were still being integrated and, much to the surprise of the observatory team, a historic sight was recorded.

Sometimes, science just happens to you.

The science foundation's Daniel K. Inouye Solar Telescope, located on the island of Maui in Hawaii, happened upon the 10,000-mile-wide sunspot.

Even though the sunspot resembles the massive Eye of Sauron from the Lord of the Rings (not to be confused with the nebula M 1-42, in the constellation Sagittarius), this sunspot is a mere speck on the surface of the sun.

What causes sunspots — They are caused by the magnetic field inhibiting the transfer of energy on the surface of the Sun through the process of convection, where hot fluid rises and cooler fluid sinks.

The image reveals the structure of a sunspot in great detail, with an influx of hot and cold gas shown as streaks that spiral out from the dark center.

Friedrich Woeger, the telescope's instrument systems scientist at the National Solar Observatory, recalls the team's excitement as they pointed the telescope towards a sunspot for the first time in January and captured it in great detail.

"What we physicists typically do is compare our observations with models, the models try to predict what we are seeing on the Sun," Woeger tells Inverse. "In general, these models are very good but the devil is in the details."

The image was released last week, along with an article about the Inouye telescope, in the Solar Physics Journal.

HIGH-REZ SUN PICS —The new image is two and a half times higher in resolution than previous ones, allowing the team at the solar observatory to resolve the small scale structures on the Sun.

Although they are small, sunspots are the only visible indication of solar activity. The more sunspots that can be observed across the surface of the Sun, the more active the Sun is and vice versa.

Solar activity largely depends on the Sun's magnetic field. The Sun’s magnetic field goes through a periodic cycle in which the south and north poles essentially switch spots, and it takes another 11 years or so for them to switch back.

"We have observations that show what we were to expect, but the details are different and they are very revealing of the inner processes," Woeger says.

The sunspot's center has a high concentration of magnetic fields, suppressing heat within the Sun from reaching its surface. The temperature of the dark center reaches more than 7,500 degrees Fahrenheit, which is still relatively cooler than the surrounding temperatures on the Sun.

Why it matters to you, an earthling — Because they serve as clues as to how active the Sun is, sunspots are associated with solar wind eruptions, coronal mass ejections, and solar flareups, which are all part of solar activity.

"One of the things that is very important is that we get a view into the smallest details so that we can improve our models, and improve how well we can predict eruptions on the Sun," Woeger says. "Sunspots are magnetic structures on the Sun that can cause explosions, and these explosions can affect us on Earth."

When these solar flares reach Earth, they penetrate through Earth's protective layer of the atmosphere, known as the magnetosphere, and wreak havoc on our electric equipment and power grids, as well as orbiting spacecraft and astronauts.

On August 7, 1972, a massive solar storm erupted from the Sun's surface, disrupting radio waves, telecommunication networks, and power systems by triggering an intense magnetic storm on Earth.

In the past 20 years, scientists have come a long way in understanding the different processes that govern the Sun's activity but it is still a work in progress. The better they can understand solar activity, the better they can predict the solar storms that erupt from the Sun.