Total Eclipse: Solar Research Thrives in Darkness

On Aug 21, the moon will cross between the Earth and the sun, casting a 70-mile-wide shadow onto the planet’s surface that will cut a path across the U.S. from the West Coast to the East. Those directly in its path—the path of totality—will experience what’s called a total solar eclipse, when the moon completely blocks the sun’s light.

A total solar eclipse provides scientists with a unique opportunity to observe certain features of the sun; in particular, the mysterious corona. Understanding these features is not simply a matter of sating scientific curiosity, though. It’s critical for a technologically dependent society, whose Earth-based instruments and satellites are impacted daily by solar activity.

Research funded by the National Science Foundation (NSF), including through the NSF-supported National Solar Observatory (NSO) and  National Center for Atmospheric Research (NCAR), is helping illuminate the intimate relationship between us and our closest star.

Sunspot Central

Sunspots, which appear as dark patches on the sun’s surface, called the photosphere, denote intense magnetic activity. At 7,000 degrees Fahrenheit, these areas are cooler, and thus darker, than the surrounding surface area, which can reach temperatures of 10,000 degrees Fahrenheit.

Sunspot activity waxes and wanes during an 11-year cycle. During the solar maximum, when sunspots are more numerous, the Earth’s atmosphere is rocked by geomagnetic storms, which impact everything from communications networks to satellites.

Interestingly, an NSF-funded study also found that the Earth is bombarded by high speeds of solar energy during even quiet phases, called the solar minimum, when sunspots are fewer or have disappeared.

The Middle Child

Between the photosphere and the corona, the sun’s chromosphere roils and churns. One of three main outer layers that make up the sun’s atmosphere, the chromosphere often appears red as superheated hydrogen emits light. When viewed during a total solar eclipse, the red rim of the chromosphere is just visible to the naked eye.

This image, taken with the Interferometric BIdimensional Spectrometer at the NSO’s Richard B. Dunn Solar Telescope, reveals solar features seen best through a spectrograph. These include bright areas surrounding sunspots, called plages, that are associated with strong magnetic fields. A solar flare can also be seen erupting to the right of the sunspot in the lower right. Cool, thread-like features magnetically suspended above the sun’s surface, called filaments or solar prominences, are visible in the center and upper left.

HIAPER Speed

Many scientists are taking advantage of the upcoming eclipse to conduct one-of-a-kind research. Scientists at the NCAR and the Smithsonian Astrophysical Observatory are collaborating on an experiment that will take place aboard the NSF/NCAR Gulfstream-V High-performance Instrumented Airborne Platform for Environmental Research (GV HIAPER) aircraft. As they fly along a section of the eclipse path, their infrared measurements of the lower solar corona may lead to a better understanding of solar winds and space weather.

NSF-funded researchers at George Mason University are combining citizen science and basic research to study radio wave propagation as the moon blocks the sun, which will cause a sudden change in the Earth’s ionosphere. Their project, called EclipseMob, will analyze data from 200 custom-built radio receivers at schools around the country. A team at Boston University is looking to construct a high-resolution picture of the Earth’s ionosphere using GPS signals from smartphones, which can measure the number of ions between the phone and a GPS satellite.

Auroral Storms

The aurora australis lights up the dark sky above the South Pole. Auroras—both the aurora borealis in the Northern Hemisphere and the aurora australis in the Southern Hemisphere—appear when charged particles from the sun, carried by a solar wind, run headlong into the Earth’s own magnetically charged atmosphere. More than just a dazzling light show, auroras are of interest to scientists because of their association with solar storms.

The NSF-supported Aurorasaurus project leverages the power of citizen science by amassing data from thousands of aurora watchers around the world who help track the auroras in real-time. Studying the data, scientists are hoping to learn more about the storms that can disrupt or destroy the Earth's communications networks and affect the planet's navigation, pipeline, electrical and transportation systems.

Polar Opposites

The sun, like the Earth, has two poles, similar to a bar magnet. On the sun, magnetic fields wrap themselves up over approximately a five- to six-year period. They then spend the next five years winding down, relaxing and producing solar flares and coronal mass ejections to release excess energy.

Scientists are not able to observe magnetic fields directly so they use hot gases in the sun’s atmosphere to trace out magnetic field lines. During solar maximum, when sunspots are numerous and solar activity is at its peak, magnetic lines surround the sun. During solar minimum, which is when the upcoming eclipse will occur, there is more magnetic activity at the sun’s equator and poles. Given the corona is not expected to change much before the eclipse, scientists at the NSO used current observations to create a coronal magnetic model that shows where they expect to see field lines concentrated during the eclipse.

Most Powerful Solar Observatory

Atop Haleakalā on Maui, Hawaii, construction of NSF’s DKIST—the world’s soon-to-be largest solar telescope—nears completion. The telescope’s state-of-the-art instrumentation, including a 4-meter primary mirror polished to a surface roughness of 2 nanometers (2 billionths of a meter), will give scientists an unprecedented view of the sun, and help answer long-standing fundamental questions in solar physics.  

Fundamental research conducted at DKIST will also have real-world impacts. For example, scientists using the telescope’s coronagraph to create an artificial eclipse that blocks out the sun will seek to better understand the fundamental physics behind solar eruptive events. This, in turn, will lead to better models of solar activity and improve the ability to forecast space weather.

Citizen Science

Perhaps one of the greatest impacts of the upcoming solar eclipse is the excitement it has created among people of all ages. For the first time in history, modern technology and social media make it possible for millions of people viewing the eclipse to contribute to scientific research. Images and data they collect and share through Citizen CATE (Continental-America Telescopic Eclipse) and other citizen science projects will be analyzed for years to come.

NSF’s support of fundamental solar research and the development of sophisticated instruments to investigate our star’s mysterious nature will continue to advance the understanding of the sun and its impact on our planet.

The images in this National Science Foundation gallery are copyrighted and may be used only for personal, educational and nonprofit/non-commercial purposes. Credits must be provided.                   - Discover Magazine

Total Eclipse: Solar Research Thrives in Darkness

On Aug 21, the moon will cross between the Earth and the sun, casting a 70-mile-wide shadow onto the planets surface that will cut a path across the U.S. from the West Coast to the East. Those directly in its paththe path of totalitywill experience whats called a total solar eclipse, when the moon completely blocks the suns light. A total solar eclipse provides scientists with a unique opportunity to observe certain features of the sun; in particular, the mysterious corona. Understanding these features is not simply a matter of sating scientific curiosity, though. Its critical for a technologically dependent society, whose Earth-based instruments and satellites are impacted daily by solar activity. Research funded by the National Science Foundation (NSF), including through the NSF-supported National Solar Observatory (NSO) and National Center for Atmospheric Research (NCAR), is helping illuminate the intimate relationship between us and our closest star. Sunspot Central Sunspots, which appear as dark patches on the suns surface, called the photosphere, denote intense magnetic activity. At 7,000 degrees Fahrenheit, these areas are cooler, and thus darker, than the surrounding surface area, which can reach temperatures of 10,000 degrees Fahrenheit. Sunspot activity waxes and wanes during an 11-year cycle. During the solar maximum, when sunspots are more numerous, the Earths atmosphere is rocked by geomagnetic storms, which impact everything from communications networks to satellites. Interestingly, an NSF-funded study also found that the Earth is bombarded by high speeds of solar energy during even quiet phases, called the solar minimum, when sunspots are fewer or have disappeared. The Middle Child Between the photosphere and the corona, the suns chromosphere roils and churns. One of three main outer layers that make up the suns atmosphere, the chromosphere often appears red as superheated hydrogen emits light. When viewed during a total solar eclipse, the red rim of the chromosphere is just visible to the naked eye. This image, taken with the Interferometric BIdimensional Spectrometer at the NSOs Richard B. Dunn Solar Telescope, reveals solar features seen best through a spectrograph. These include bright areas surrounding sunspots, called plages, that are associated with strong magnetic fields. A solar flare can also be seen erupting to the right of the sunspot in the lower right. Cool, thread-like features magnetically suspended above the suns surface, called filaments or solar prominences, are visible in the center and upper left. HIAPER Speed Many scientists are taking advantage of the upcoming eclipse to conduct one-of-a-kind research. Scientists at the NCAR and the Smithsonian Astrophysical Observatory are collaborating on an experiment that will take place aboard the NSF/NCAR Gulfstream-V High-performance Instrumented Airborne Platform for Environmental Research (GV HIAPER) aircraft. As they fly along a section of the eclipse path, their infrared measurements of the lower solar corona may lead to a better understanding of solar winds and space weather. NSF-funded researchers at George Mason University are combining citizen science and basic research to study radio wave propagation as the moon blocks the sun, which will cause a sudden change in the Earths ionosphere. Their project, called EclipseMob, will analyze data from 200 custom-built radio receivers at schools around the country. A team at Boston University is looking to construct a high-resolution picture of the Earths ionosphere using GPS signals from smartphones, which can measure the number of ions between the phone and a GPS satellite. Auroral Storms The aurora australis lights up the dark sky above the South Pole. Aurorasboth the aurora borealis in the Northern Hemisphere and the aurora australis in the Southern Hemisphereappear when charged particles from the sun, carried by a solar wind, run headlong into the Earths own magnetically charged atmosphere. More than just a dazzling light show, auroras are of interest to scientists because of their association with solar storms. The NSF-supported Aurorasaurus project leverages the power of citizen science by amassing data from thousands of aurora watchers around the world who help track the auroras in real-time. Studying the data, scientists are hoping to learn more about the storms that can disrupt or destroy the Earths communications networks and affect the planets navigation, pipeline, electrical and transportation systems. Polar Opposites The sun, like the Earth, has two poles, similar to a bar magnet. On the sun, magnetic fields wrap themselves up over approximately a five- to six-year period. They then spend the next five years winding down, relaxing and producing solar flares and coronal mass ejections to release excess energy. Scientists are not able to observe magnetic fields directly so they use hot gases in the suns atmosphere to trace out magnetic field lines. During solar maximum, when sunspots are numerous and solar activity is at its peak, magnetic lines surround the sun. During solar minimum, which is when the upcoming eclipse will occur, there is more magnetic activity at the suns equator and poles. Given the corona is not expected to change much before the eclipse, scientists at the NSO used current observations to create a coronal magnetic model that shows where they expect to see field lines concentrated during the eclipse. Most Powerful Solar Observatory Atop Haleakalā on Maui, Hawaii, construction of NSFs DKISTthe worlds soon-to-be largest solar telescopenears completion. The telescopes state-of-the-art instrumentation, including a 4-meter primary mirror polished to a surface roughness of 2 nanometers (2 billionths of a meter), will give scientists an unprecedented view of the sun, and help answer long-standing fundamental questions in solar physics. Fundamental research conducted at DKIST will also have real-world impacts. For example, scientists using the telescopes coronagraph to create an artificial eclipse that blocks out the sun will seek to better understand the fundamental physics behind solar eruptive events. This, in turn, will lead to better models of solar activity and improve the ability to forecast space weather. Citizen Science Perhaps one of the greatest impacts of the upcoming solar eclipse is the excitement it has created among people of all ages. For the first time in history, modern technology and social media make it possible for millions of people viewing the eclipse to contribute to scientific research. Images and data they collect and share through Citizen CATE (Continental-America Telescopic Eclipse) and other citizen science projects will be analyzed for years to come. NSFs support of fundamental solar research and the development of sophisticated instruments to investigate our stars mysterious nature will continue to advance the understanding of the sun and its impact on our planet. The images in this National Science Foundation gallery are copyrighted and may be used only for personal, educational and nonprofit/non-commercial purposes. Credits must be provided. - Discover Magazine