By Kevin Roeten:
What can we learn from the eclipse, sunspot activity and “global warming”?
On Sept. 30, 2014, multiple NASA observatories watched a solar eruption. Some dense solar material erupted from the surface. However, the eruption collapsed by magnetic forces. Scientists tracked the entire event, and explain how the Sun’s magnetic landscape terminated a solar eruption. Everything is in The Astrophysical Journal.
“Each component of our observations was very important,” said solar physicist Georgios Chintzoglou. The study uses all data captured by NASA’s Solar Dynamics Observatory, NASA’s Interface Region Imaging Spectrograph, and JAXA/NASA’s Hinode. “We were expecting an eruption; this was the most active region on the Sun that day,” said Angelos Vourlidas, an astrophysicist at John Hopkins. “We saw the filament lifting with IRIS, but we didn’t see it erupt in SDO or in the coronagraphs. That’s how we knew it failed.”
The sun is controlled by magnetic forces, and scientists deduced the filament must have met some magnetic boundary preventing the unstable structure from erupting. Typically, when solar structures with opposite magnetic orientations collide, they explosively release magnetic energy, heating the atmosphere with a flare and erupting into space as a coronal mass ejection.
This study indicates the Sun’s magnetic topology plays an important role in whether or not an eruption can burst from the Sun.
On Sept. 30, 2014, multiple NASA observatories watched what appeared to be the beginnings of a solar eruption. A filament consisting of dense solar material rose from the surface, gaining energy and speed. But instead of erupting from the Sun, the filament collapsed, shredded to pieces by invisible magnetic forces.
Because scientists had so many instruments observing the event, they were able to track the entire event from beginning to end, and explain for the first time how the Sun’s magnetic landscape terminated a solar eruption. Their results are summarized in a paper published in The Astrophysical Journal on July 10, 2017.
The study makes use of a wealth of data captured by NASA’s Solar Dynamics Observatory, NASA’s Interface Region Imaging Spectrograph, JAXA/NASA’s Hinode, and several ground-based telescopes in support of the launch of the NASA-funded VAULT2.0 sounding rocket.
The total solar eclipse will also have the sudden loss of extreme ultraviolet radiation from the Sun, which generates the ionosphere. “The eclipse turns off the ionosphere’s source of high-energy radiation,” said Bob Marshall, at University of Colorado. “Without ionizing radiation, the ionosphere will relax, going from daytime conditions to nighttime conditions and then back again after the eclipse.” Stretching from 50-400 miles above Earth’s surface, the ionosphere is an electrified layer of the above atmosphere reacting to a major change.
“In our lifetime, this is the best eclipse to see,” said Greg Earle, at Virginia Tech. “But we’ve also got a denser network of satellites, GPS and radio traffic than ever before. It’s the first time we’ll have such a wealth of information to study the effects of this eclipse; we’ll be drowning in data.” “Compared to visible light, the Sun’s extreme ultraviolet output is highly variable,” said Phil Erickson, from MIT.
Probing the Ionosphere
The ionosphere is divided into three regions in altitude based on what wavelength of solar radiation is absorbed: the D, E and F, with D being the lowermost region and F, the uppermost. “Just because the density is low, doesn’t mean it’s unimportant,” Marshall said. “The D-region has implications for communications systems actively used by many military, naval and engineering operations.”
They combine their data with missions such as NOAA’s Geostationary Operational Environmental Satellite, NASA’s Solar Dynamics Observatory and NASA’s Ramaty High Energy Solar Spectroscopic Imager, to get the Sun’s radiation on the ionosphere. MIT will use data to track ionospheric disturbances, usually linked to atmospheric gravity waves. Using ionosondes,scientists will measure the ionosphere’s height and density. “We’re looking at the bottom side of the F-region, and how it changes during the eclipse,” Earle said. “This is the part of the ionosphere where changes in signal propagation are strong.”
Two Weeks in the Life of a Sunspot
In July of 2017, NASA’s Solar Dynamics Observatory watched an area of complex magnetic fields rotate into view on the Sun. With magnetic fields, sunspots are often the source of interesting solar activity: During its 13-day trip across the face of the Sun, it put on a show for NASA’s Sun-watching satellites, producing several solar flares, and a coronal mass ejections.
The Sun is moving steadily toward a period of lower solar activity called solar minimum. It always occurs on an 11-year cycle. Space-Weather centers monitor these spots to provide advance warning, of the radiation bursts coming toward Earth. M-class flares are a tenth the size of the most intense flares, the X-class flares. An M2 is twice as intense as an M1, an M3 is three times as intense.
This was accompanied by another kind of solar explosion called a coronal mass ejection[CME]. Solar flares are often associated with CMEs. NASA’s Solar and Heliospheric Observatory[SOHO], saw the CME leaving the Sun at speeds of 620 miles/second. Using a model called ENLIL, they are able to whether a solar storm will impact our spacecraft.
When a CME made contact with Earth’s magnetic field on July 16, the sunspot’s journey across the Sun was almost complete. As for the solar storm, it took this massive cloud of solar material two days to travel 93 million miles, where it caused charged particles to stream down Earth’s magnetic poles, giving enhanced aurora.
Chasing The Eclipse From WB-57F Jets
For most viewers, the Aug. 21, 2017, total solar eclipse lasted less than two and half minutes. But for one team of NASA-funded scientists, the eclipse lasted over seven minutes. But here, they follow the shadow of the Moon in two WB-57F jet planes.
“These could well turn out to be the best ever observations of high frequency phenomena in the corona,” says Dan Seaton, Boulder, Colorado. “Extending the observing time and going to very high altitude might allow us to see a few events or track waves that would be essentially invisible in just two minutes of observations from the ground.”
The total solar eclipse provides a rare opportunity to study the Sun, and its atmosphere. As the Moon completely blocks the Sun and its light during an eclipse, the faint corona is easily seen against the dark sky.
The corona is heated to millions of degrees, yet the photosphere is only heated to a few thousand degrees. Scientists aren’t sure how this inversion happens. Alternatively, micro explosions, termed nanoflares might release heat into the corona.
No one has yet directly seen nanoflares, but the high-resolution to be taken from the WB-57F jets will reveal effects on the corona. Nanoflares may be the missing link responsible for untangling the magnetic field lines on the surface of the Sun, explaining why the corona has neat loops and smooth fans of magnetic fields. The two planes, will observe the total eclipse for about three and a half minutes each as they fly over Missouri, Illinois and Tennessee. By flying high in the stratosphere, observations taken with onboard telescopes will avoid looking through the majority of Earth’s atmosphere, greatly improving image quality. At the planes’ cruising altitude of 50,000 feet, the sky is 20-30 times darker than as seen from the ground, and there is much less atmospheric turbulence, allowing the Sun’s corona to be visible.
It must be kept in mind, sunspots visible in this picture are minimal at this point. In other words, the sun going into another solar “minimum” after its 11 year cycle. No global warming will be occurring.
Kevin Roeten can be reached at roetenks@CHARTER.NET.
© Copyright by Kevin Roeten, 2017. All rights reserved.