“There’s never been an event like this in human history, where so many people can participate and with such unique technology,” Carrie E. Black, associate program director for the foundation’s division of atmospheric and geospace sciences, said during a gathering of astrophysicists in Boulder last month. “This is being treated as a natural laboratory.”
She expects millions of people will watch the eclipse, many of whom might collect images that she said will be analyzed by scientists for years to come. That deluge of data from both professional astronomers and amateurs might one day help scientists with forecasting eruptive solar ejections, or “space weather,” detrimental to communication satellites and power grids.
“Just as it takes a village to raise a child,” said Madhulika Guhathakurta, NASA’s lead scientist for the 2017 eclipse, “I would say that it takes the entire U.S.A. to really gather the information of various kinds — scientific, psychology, animal behavior — to really fully understand how intimately we are connected to our star.”
Eyes in the Sky
This is the first time that the modified Gulfstream V, which carries sensors and equipment for atmospheric research, will study space.
“The camera will be right here looking straight up,” said Dr. Lussier, pointing to a specially made 6-by-9-inch porthole in the top of a plane. “We’ll be able to see the whole eclipse through this window.”
From their eye in the sky, the researchers will experience totality, the point at which the moon completely blocks the sun, for about four minutes, while those below will see about two and a half minutes.
The scientists will use the extra time, and a large device known as a spectrometer, to observe the sun’s corona, the sheath of plasma surrounding our star. The corona is visible from Earth only during a total solar eclipse, and scientists use the phenomenon to study its properties.
Because of several technological advances in the last few decades, this eclipse offers scientists the chance to observe the corona in the infrared spectrum, which may reveal insight into the sun’s magnetic fields. The data could help answer a longstanding puzzle: Why does the corona burn at millions of degrees Fahrenheit, much hotter than the sun’s surface?
Jenna Samra, a doctoral candidate in applied physics at the Harvard-Smithsonian Center for Astrophysics, is a lead researcher on the project and helped design the device. She is looking to identify five lines of infrared emissions that are created when electrons in the corona bump into charged particles in the plasma, potentially freeing other electrons.
“If we see them it’s going to eventually give us a way to measure the magnetic field,” she said. That could be used to make a future instrument that observes the magnetic field.
That’s important, she said, because it could one day help scientists better predict space weather. When the sun’s magnetic field lines twist and then snap, they can launch billions of tons of plasma across the solar system. One such powerful ejection in 2012 could have been catastrophic to our power grid had it hit the planet.
Ms. Samra will be on the plane, well above pesky clouds or storms, as well as most of the water vapor in the atmosphere, which strongly absorbs the infrared radiation. The plane will fly from southeast Missouri, across Kentucky and finally to Tennessee. Her flight may sound exhilarating, but Ms. Samra said she will most likely be unable to see the actual eclipse because of its angle above the horizon.
“It’s the first of its kind,” said Scott McIntosh, the director of the NCAR High Altitude Observatory. “Should it be successful on Aug. 21, it opens the door for a brand-new platform for eclipse science.”
The Gulfstream V will not be the only jet chasing the total solar eclipse. Two WB-57F aircraft operated by NASA and outfitted with nose-mounted high-tech telescopes will take off from Houston and fly over Missouri, Illinois and Tennessee, each chasing about three and a half minutes of totality and clear views of the corona.
Only two people will be aboard each jet: the pilot and a sensor equipment operator who will be running the cameras. Amir Caspi, an astrophysicist with the Southwest Research Institute in Boulder and the principal investigator for the project, will be watching from a control room in Houston.
“This will be my first eclipse, and I don’t get to see it,” said Dr. Caspi. “I get to watch it on TV.”
By spying on the sun’s outer atmosphere through two telescopes, one that uses a green filter and another that detects infrared radiation, Dr. Caspi and his colleagues hope to better understand the corona’s structure and why it is so hot.
“We don’t see a big tangled mess of magnetic fields,” Dr. Caspi said. “We see organized loops and arcades unlike in our modeling, where everything looks like it’s very tangled and snarled — like bed hair in the morning, and not like a freshly combed head of hair.”
The cameras aboard the planes will take high-definition images of the sun 30 times per second. One telescope will observe green emissions from ionized iron atoms in the sun’s outer atmosphere.
Dr. Caspi and his team will use that equipment to search for magnetic waves in the corona as well as evidence of nanoflares, which are tiny explosions in the sun’s atmosphere. Both may hold clues to understanding how the corona gets superheated.
As an added bonus, half an hour before and after totality the planes will turn their infrared observations to Mercury to gather insights into the tiny planet’s composition.
While the planes set their sights on the sun, plenty of scientists on the ground will be focusing on the Earth during the eclipse.
One area of particular interest is the ionosphere, a region in the upper atmosphere that is home to the International Space Station and through which signals pass from communications and Global Positioning System satellites that billions of people rely on. The eclipse will provide an opportunity for researchers to investigate how the ionosphere reacts to cosmic disturbances.
In a way, the ionosphere breathes, said Greg Earle, a professor of electrical engineering at Virginia Tech.
During the day, the sun’s ultraviolet light helps produce trillions of charged particles floating in the upper atmosphere, causing the ionosphere to “inhale” and get bigger. At night, it exhales and loses density. Scientists have constructed models that show how these changes occur every day.
But “the eclipse is like a punch in the face,” Dr. Earle said.
It will shut off the sun and create a disturbance that the ionosphere does not normally experience. That interests scientists like him because it provides an opportunity to test the accuracy of their models.
“The eclipse is a particularly strong example, for a brief period of time, of space weather,” said Philip Erickson, a space scientist at the Massachusetts Institute of Technology’s Haystack Observatory.
Unlike solar flares or coronal mass ejections, an eclipse is an easily predictable event that produces a relatively small disturbance. According to existing models, the one next week will create a large hole in the ionosphere that will travel over most of North America over the course of two or three hours, creating nighttime conditions in the upper atmosphere.
“We’re interested in how deep this hole is and how long it will recover after the spot moves on,” he said.
During the eclipse, scientists like Dr. Erickson and Dr. Earle will use a suite of tools, from powerful radars and orbiting satellites to GPS sensors and ham radios operated by citizen scientists.
Dr. Erickson said they are laying the groundwork to make it possible in the future to more accurately predict the kind of havoc that major space weather episodes can cause in the ionosphere, which would allow us to better protect the critical technology that orbits our planet.
“Humans inevitably will become a space-faring society,” Dr. Erickson said. “Understanding the space weather in the natural environment of space is a key challenge to allowing us to gradually move off the planet.”
Continue reading the main story