Posted on by Mark Thompson

Solar Explosions Spark Controversy

Solar Prominence

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Nowhere in the Solar System are conditions more extreme than the Sun. Every second it converts millions of tons of matter into energy to create the intense levels of heat and light we expect of our local star. Study the Sun in different wavelengths and its violent nature can really become apparent. The STEREO satellite has been studying the Sun at a wavelength of 304Å and the results support a controversial solar theory.

Coronal Mass Ejections (or CMEs) are common on the Sun and they have a very real impact to us here on Earth. The solar explosions expel trillions of trillions of tons of super hot hydrogen gas into space, sometimes in the direction of the Earth. Traveling at speeds up to 2,000 kilometers per second it takes just a day for the magnetized gas to reach us and on arrival it can induce strong electric currents in the Earth’s atmosphere leading not only to the beautiful auroral displays but also to telecommunication outages, GPS system failures and even disturbances to power grids.

Solar flares, to use their other name, were first observed back in 1859 and since then, scientists have been studying them to try to understand the mechanism that causes the eruption. It has been known for some time that the magnetically charged gas or plasma is interacting with the magnetic field of the Sun but the detail has been at best, elusive.

In 2006, the international satellite STEREO was launched with the objective of continuously monitoring and studying the CMEs as they head toward the Earth and its data has helped scientists at the Naval Research Laboratory (NRL) in Washington, D.C., start to understand the phenomenon.

Using this new data, scientists at the NRL compared the observed activity with a controversial theory that was first proposed by Dr James Chen (also from the NRL) in 1989. His theory suggested that the erupting clouds of plasma are giant ‘magnetic flux ropes’, effectively a twisted up magnetic field line shaped like a donut. The Sun being a vast sphere of gas suffers from differential rotation where the polar regions of the Sun and the equatorial regions all rotate at different speeds. As a direct result of this, the plasma ‘drags’ the magnetic field lines around and the Sun and it gets more and more twisted up . Eventually, it bursts through the surface, taking some plasma with it giving us one of the most dramatic yet potentially destructive events in the Universe.

Dr Chen and a Valbona Kunkel, a doctorate student at George Mason University, applied Dr. Chen’s model to the new data from STEREO and found that the theory agrees with the measured trajectories of the ejected material. It therefore looks like his theory, whilst controversial may have been right all along.

Its strange to think that our nearest star, the Sun, still has secrets. Yet thanks to the work of Dr. Chen and his team, this one seems to have been unraveled and understanding the strange solar explosions will perhaps help us to minimise impact to Earth based technologies in years to come.

Mark Thompson is a writer and the astronomy presenter on the BBC One Show. See his website, The People’s Astronomer, and you can follow him on Twitter, @PeoplesAstro

Posted on by Nancy Atkinson

Astrophotos: Halo Around the Sun in South Africa Today

A halo appeared around the Sun on Nov. 1, 2010 in Centurion South Africa. Credit: Alan Buff.

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Residents around Johannesburg, South Africa were treated with a rare astronomical (or actually atmospheric) sight — a halo around the Sun. These halos are striking to see, but unlike an eclipse, they can’t be predicted. Conditions in the atmosphere have to be just right, with moisture or ice crystals creating a “rainbow” effect around the Sun. Sometimes the halos surround the Sun completely, other times, they appear as arcs around the solar sphere. Basically, sunlight is reflecting off moisture in the atmosphere. These images were sent in by Alan Buff from Centurion, South Africa. See more below.

Another image of a halo that appeared around the Sun on Nov. 1, 2010 in Centurion South Africa; this one has a building blocking out the Sun itself. Credit: Alan Buff.

In folklore, these halos seen around the Sun or the Moon means precipitation is on the way, which makes sense, since moisture in the atmosphere usually makes it down to the ground. High clouds of ice crystals are called cirrus clouds, and these often form in at the leading edge of warm fronts that bring rain.

Newspaper and internet articles report that Johannesburg was buzzing about the weird halos; however, the explanation was simple and did not include aliens or end-of-the-world scenarios.

A halo appeared around the Sun on Nov. 1, 2010 in Centurion South Africa. Credit: Alan Buff.

Thanks again to Alan Buff for sharing his images with Universe Today.

Sources: eHow, NewsTime, NASA

Posted on by Nancy Atkinson

Spacecraft Calibrations Provide Unique Solar “Artwork”

Sun 'artwork' by the Solar Dynamics Observatory

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If you check out the Solar Dynamics Observatory website today to get an update of what the Sun is doing, (which you should -everyday!) you may have noticed a few of the daily images appeared to be “sliding” across the screen. That’s because yesterday the team from the AIA instrument (Atmospheric Imaging Assembly) performed several instrument calibration maneuvers, in which the AIA boresight was moved away from the center of the Sun. When the images are re-centered some of them have lines to the edges of the picture, creating some very nifty solar artwork. Enjoy them now, as this effect will only show up in the “rapid” images shown on their website, and later, they’ll be corrected in the science database. See more below.

More SDO artwork.

SDO takes images of the Sun in several different wavelengths, which highlights different features. On SDO’s Facebook page, the team wrote, “It appears that the re-centering of the images is copying the value at the edge of the field of view rather than zero while the image is being shifted to the center of the picture.”

And even though the images will be fixed, they won’t be able to fix them completely. The information that is missing from images can’t be recovered because the instrument wasn’t pointed at the Sun at the time the image was taken.

More SDO artwork.
Posted on by Nancy Atkinson

Mysterious Ribbon at Edge of Solar System is Changing

A year ago, researchers from the IBEX mission – NASA’s Interstellar Boundary Explorer – announced the discovery of an unexpected bright band or ribbon of surprisingly high energy emissions at the boundary between our solar system and interstellar space. Now, after a year of observations, scientists have seen vast changes, including an unusual knot in the ribbon which appears to have ‘untied.’ Changes in the ribbon — a ‘disturbance in the force,’ so to speak, along with a shrunken heliosphere, may be allowing galactic cosmic rays to leak into our solar system.
Continue reading “Mysterious Ribbon at Edge of Solar System is Changing”

Posted on by Nancy Atkinson

Solar Dynamics Observatory Earns its Stripes

Is this a new object is space that is half Sun and half Jupiter? Sunpiter? Credit: NASA/SDO

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“Now we know what it would look like if Jupiter and the sun had a child,” joked Ralph Seguin of the Lockheed-Martin Solar and Astrophysics Lab, trying to explain this weird image. So, just what is it? Some people have been calling it “Sunpiter,” since parts of it looks like the Sun, and other parts look like Jupiter. It really is the Sun, as seen by the Solar Dynamics Observatory, which was having a tough day. Normally, SDO gets a great view of the Sun, but the spacecraft occasionally gets its view blocked by the Earth, in a unusual kind of eclipse. This image is a composite of multiwavelength images and a magnetogram taken by SDO just as the sun was emerging from its daily blackout. “SDO has entered eclipse season,” said Seguin. “Around the time of the equinoxes, the spacecraft, Earth, and sun can line up almost perfectly. Once a day for about an hour, Earth blocks SDO’s view of the sun.” And this is the result.

Magnetograms are computed from a series of images taken over a short time span. The ribbons of color result from Earth’s motion across the sun during the series of exposures. This eclipse season for SDO lasts until October 6, 2010.

You can see a short movie clip here of what SDO sees during an eclipse, which isn’t much.

Source: Spaceweather.com

Posted on by Nancy Atkinson

Amazing Sunspot Image from New Solar Telescope

The most detailed sunspot ever obtained in visible light was seen by new telescope at NJIT's Big Bear Solar Observatory. Credit: Big Bear Solar Observatory

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A new type of adaptive optics for solar observations has produced some incredible results, providing the most detailed image of a sunspot ever obtained in visible light. A new telescope built by the New Jersey Institute of Technology’s Big Bear Solar Observatory has seen its ‘first light’ using a deformable mirror, which is able to reduce atmospheric distortions. This is the first facility-class solar observatory built in more than a generation in the U.S.

The New Solar Telescope (NST) is located in the mountains east of Los Angeles. It has 97 actuators that make up the deformable mirror. By the summer of 2011, in collaboration with the National Solar Observatory, BBSO will have upgraded the current adaptive optics system to one utilizing a 349 actuator deformable mirror. The telescope has a 1.6 m clear aperture, with a resolution covering about 50 miles on the Sun’s surface.

The NST will be the pathfinder for an even larger ground-based telescope, the Advanced Technology Solar Telescope to be built over the next decade. Philip R. Goode from NJIT is leading a partnership with the National Solar Observatory (NSO) to develop a new and more sophisticated kind of adaptive optics, known as multi-conjugate adaptive optics. This new optical system will allow the researchers to increase the distortion-free field of view to allow for better ways to study these larger and puzzling areas of the Sun, and a 4-meter aperture telescope will be built in the next decade.

Source: NJIT

Posted on by Nancy Atkinson

Amazing Image: Map of Magnetic Field Lines of the Sun

Magnetic field lines on the Sun, on August 20, 2010. Credit: NASA SDO/Lockheed Martin Space Systems Compan

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The Sun’s corona is threaded with a complex network of magnetic fields, and this amazing new image from the Solar Dynamics Observatory shows the magnetic field lines associated with a coronal hole that is now turning to face Earth. This map is from data taken on August 20, 2010 by the Helioseismic and Magnetic Imager instrument (HMI). The magnetic field lines are color coded: white lines show fields that are closed, not releasing solar wind, and gold lines show open fields, letting solar wind escape. Understanding these magnetic fields is important because it is thought that solar storms and flares, which can affect us here on Earth, result from changes in the structure and connections of these fields.

Coronal holes are large regions in the corona that are darker, less dense and cooler than surrounding areas. The open structure of their magnetic field allows a constant flow of high-density plasma to stream out of the holes. There is an increase in the intensity of the solar wind effects on Earth when a coronal hole faces.

During a solar minimum, such as the one from which the Sun is just emerging, coronal holes are mainly found at the Sun’s polar regions, but they can be located anywhere on the sun during solar maximum. The fast-moving component of the solar wind is known to travel along open magnetic field lines that pass through coronal holes.

Scientists are finding out that much of the structure of the Sun’s corona is shaped by the magnetic field. Although it varies over time and from place to place on the Sun, the Sun’s magnetic field can be very strong. Inside sunspots, the magnetic field can be several thousand times the strength of the Earth’s magnetic field.

Learn more about magnetic field lines and how SDO’s HMI instrument will help us to better understand the Sun in this video from SDO:

More info: HMI webpage, SDO website

Sources: @Camilla_SDO Twitpic page, SDO Facebook, Solar Physics page from Montana University

Posted on by Nancy Atkinson

Venus and Mercury Blasted by Recent Solar Storms

A plot of the STEREO data from August 14, 2010, showing the location of the planets and the direction of a CME from the Sun.

Update: Well, it turns out that while it looks like Venus and Mercury are getting pummeled by Coronal Mass Ejections, the geometry might not work out, at least not for every day that is included in the video above. UT reader Steven Janowiecki brought it to my attention that just because Mercury and Venus look close to the Sun doesn’t mean they’re actually in the line of fire, as they could be well behind or in front of the solar storm. I checked with STEREO project scientist Dr. Joseph Gurman, who took a look at the data. He put together a plot for August 14, (see below) and said, “It shows that Mercury and Venus are well to the East (left) of the Sun-earth line. The large CME on the 14th originated from an active region near the west limb of the Sun, and since most CME’s are about 60 degrees of heliolongitude in width on average, it’s unlikely that that event actually passed by Mercury or Venus.” There was one large event, however, on August 7, that appeared likely to be headed in the direction of Mercury and Venus.

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So, as it happens sometimes in astronomy, things are not always as they appear, and this exemplifies the challenges of estimating distance in astronomy.

The STEREO website has a very nifty tool where you can see the location of the spacecraft on any date, as well as where the planets are in their orbits. And there is another tool where you can see and download images from a particular day and time and even put together movies of a specific time period showing STEREO data.

Here’s the rest of the article as it ran originally:

Take a look at these Coronal Mass Ejections (CME) from the first part of August 2010, as seen by the two STEREO spacecraft. Here on Earth, we’ve had some aurorae, a result of the recent solar activity. But this STEREO imagery shows Venus and Mercury were blasted by these CMEs.

STEREO consists of two spacecraft – one ahead of Earth in its orbit, the other trailing behind. With this new pair of viewpoints, scientists are able to see the structure and evolution of solar storms as they blast from the Sun and move out through space.

These movies were taken by SECCHI, a suite of remote sensing instruments on both spacecraft consisting of two white light coronagraphs that make up the Sun Centered Imaging Package (SCIP), as well as a Heliospheric Imager (HI).

SECCHI can follow three-dimensional Coronal Mass Ejections (CMEs) from the Sun’s surface, through the corona and interplanetary medium, to impact at Earth. With these instruments, scientists are getting breakthroughs in understanding the origin and consequences of CMEs, in determining their three-dimensional structure, and more, and perhaps be able to predict space weather. Combining STEREO with the new Solar Dynamics Observatory, we’ll be learning more and more about the Sun in the next few years.

As an example of SDO’s capabilities, here’s an SDO image from earlier today showing the Sun’s limb.

View of the Sun from August 18, 2010 from the Solar Dynamics Observatory. Credit: NASA/SDO

Credit: NASA STEREO/NRL

Posted on by Nancy Atkinson

The Sun is Waking Up: 5 Sunspots Today

Five sunspots appeared on the Sun on August 11, 2010. Image from SolarCycle24.com

Here’s something we’ve not seen in a long while: five sunspots on the Sun at once. Is the Sun finally waking up from its unusually long and deep solar minimum slumber? While activity on the Sun usually ebbs and flows on a fairly predictable 11-year cycle, this current cycle has been anything but conventional. In 2009, there were 260 days (71% of the time) that the Sun was ‘spotless,’ but now in 2010 so far, the Sun has had spots been spotless for only 35 days. With the last solar maximum occurring in 2001, maybe the Sun is just now ramping up to the next maximum, which is set for 2013. Recent solar flares on August 1 and 7, and now these sunspots may be signaling that the Sun is “throwing off the covers” and starting to wake up.

This marvelous image from the Solar Dynamics Observatory shows that at about 8:55 UTC on August 1, a measurable solar flare triggered an event known as a coronal mass ejection (CME). This is where the “atmosphere” of the Sun sends out a burst of energized plasma. In this case, nearly the entire Earth-facing side of the Sun was involved.

The High Energy Astrophysics Picture of the week Page used that great “covers” analogy:

The Sun, after a long sleep, is finally waking up. And like any irascible sleeper vigorously throwing off the covers. In this case the covers are composed of high-energy electrons and protons being shot out into space at a tremendous rate. The image above, obtained by the Solar Dynamics Observatory on August 1, shows almost the entire earth-facing side of the sun erupting at once. In this extreme ultraviolet image you can see evidence of extremely ultraviolent activity: a C3-class solar flare (white area on upper left), a solar tsunami (upper right), multiple filaments of magnetism lifting off the stellar surface, large-scale shaking of the solar corona, and a coronal mass ejection. The coronal mass ejection, or CME, showered the earth with charged particles, producing spectacular aurora (northern lights) as far south as Iowa and Telemark, Norway.

And another CME on August 7 has not yet triggered a major geomagnetic storm, but high latitude sky watchers should take a look tonight, just in case.

Sources: High Energy Astrophysics Picture of the Week, SolarCycle24.com, SpaceWeather.com

Posted on by Nancy Atkinson

Solar Storm Update: Best Times for Viewing Aurorae

Why is the Sun So Hot?
Image from the Solar Dynamics Observatory of the filaments coming from the Sun's surface. Credit: NASA

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The Harvard Smithsonian Center for Astrophysics released the latest information on the July 31/August 1 activity on the Sun that is just now reaching Earth. They predict we’ll have multiple opportunities for a display of the Northern Lights over the next two days. The latest word from the solar scientists is that the Sun erupted not just once, but four times. All four coronal mass ejections are headed toward Earth.

Space weather forecasts are even more challenging than regular weather forecasts, said Dr. Leon Golub, and a coronal mass ejection is like a hurricane: it’s large and fuzzy, and doesn’t always move at the same speed. Currently, the estimated arrival times are:

Wednesday, Aug. 4 – 3:00 a.m. EDT (0700 GMT on Aug. 5; aurorae not visible in daylight)
Wednesday, Aug. 4 – 1:00 p.m. EDT (1600 GMT, again the daylight issue)
Wednesday, Aug. 4 – 8:00 p.m. EDT (0000 GMT on Aug. 5)
Thursday, Aug. 5 – 2:00 a.m. EDT (0600 GMT)

Any one of these events may or may not generate an aurora. It depends on details like magnetic field orientation. If the magnetic field in the oncoming solar plasma is directed opposite Earth’s magnetic field, the result could be spectacular aurorae. If the fields line up, the coronal mass ejection could slide past our planet with nary a ripple.

The Center for Astrophysics suggested these two resources:

Map of current auroral activity

Chart of proton flux (watch for the numbers to go up as each wave arrives)

Source: Harvard Smithsonian Center for Astrophyics