This image of the total solar eclipse is a combination of 30 50-millisecond exposures taken with a camera mounted on one of NASA’s WB-57 aircraft on April 8, 2024. It was captured in a wavelength of light emitted by ionised iron atoms. This Fe XIV emission highlights electrified gas, called plasma, at a specific temperature (around 3.2 million degrees Fahrenheit) that often reveals arch-like structures in the corona. CREDIT: B Justen, O Mayer, M Justen, S Habbal, and M Druckmuller.

Scientists have shared early results from NASA’s experiments on 2024’s solar eclipse which was seen across the northern hemisphere.

On April 8, 2024, a total solar eclipse swept across North America, from the western shores of Mexico, through the United States, and into northeastern Canada.

For the eclipse, NASA helped fund numerous research projects and called upon citizen scientists in support of NASA’s goal to understand how our home planet is affected by the Sun – including, for example, how our star interacts with Earth’s atmosphere and affects radio communications.  

At a press briefing at the annual meeting of the American Geophysical Union in Washington, DC, reported some early results from a few of these eclipse experiments. 

Kelly Korreck, eclipse programme manager at NASA Headquarters in Washington, said: “Scientists and tens of thousands of volunteer observers were stationed throughout the Moon’s shadow. Their efforts were a crucial part of the Heliophysics Big Year – helping us to learn more about the Sun and how it affects Earth’s atmosphere when our star’s light temporarily disappears from view.”

The eclipse’s shadow was captured from a camera aboard Virginia Tech’s balloon as part of the Nationwide Eclipse Ballooning Project on April 8, 2024. CREDIT: Nationwide Eclipse Ballooning Project/ Virginia Tech.

Changes in the Corona

The Citizen CATE 2024 (Continental-America Telescopic Eclipse) project stationed 35 observing teams from local communities from Texas to Maine to capture images of the Sun’s outer atmosphere, or corona, during totality. Their goal is to see how the corona changed as totality swept across the continent.

Sarah Kovac, the CATE project manager at the Southwest Research Institute in Boulder, Colorado, reported that, while a few teams were stymied by clouds, most observed totality successfully — collecting over 47,000 images in all. 

These images were taken in polarised light, or light oriented in different directions, to help scientists better understand the processes that shape the corona.

Kovac said: “The beauty of CATE 2024 is that we blend cutting-edge professional science with community participants from all walks of life.

“The dedication of every participant made this project possible.” 

Meanwhile, 50,000 feet above the ground, two NASA WB-57 aircraft chased the eclipse shadow as it raced across the continent, observing above the clouds and extending their time in totality to approximately six minutes and 20 seconds. 

On board were cameras and spectrometers (instruments that analyse different wavelengths of light) built by multiple research teams to study the corona. 

Shadia Habbal of the University of Hawai’i, who led one of the teams, reported that their instruments collected valuable data, despite one challenge.

Cameras they had mounted on the aircraft’s wings experienced unexpected vibrations, which caused some of the images to be slightly blurred.

However, all the cameras captured detailed images of the corona, and the spectrometers, which were located in the nose of the aircraft, were not affected.

The results were so successful, scientists are already planning to fly similar experiments on the aircraft again.

Habbal said: “The WB-57 is a remarkable platform for eclipse observations that we will try to capitalise on for future eclipses.” 

Affecting the Atmosphere

On April 8, amateur radio operators sent and received signals to one another before, during, and after the eclipse as part of the Ham Radio Science Citizen Investigation (HamSCI) Festivals of Eclipse Ionospheric Science.

More than 6,350 amateur radio operators generated over 52 million data points to observe how the sudden loss of sunlight during totality affects their radio signals and the ionosphere, an electrified region of Earth’s upper atmosphere. 

Radio communications inside and outside the path of totality improved at some frequencies (from 1-7 MHz), showing there was a reduction in ionospheric absorption.

At higher frequencies (10 MHz and above), communications worsened. 

Results using another technique, which bounced high-frequency radio waves (3-30 MHz) off the ionosphere, suggests that the ionosphere ascended in altitude during the eclipse and then descended to its normal height afterward. 

Nathaniel Frissell, a professor at the University of Scranton in Pennsylvania and lead of HamSCI, said: “The project brings [amateur] radio operators into the science community. Their dedication to their craft made this research possible.”  

Also looking at the atmosphere, the Nationwide Eclipse Ballooning Project organised student groups across the US to launch balloons into the shadow of the Moon as it crossed the country in April 2024 and during a solar eclipse in October 2023.

Teams flew weather sensors and other instruments to study the atmospheric response to the cold, dark shadow. 

This research, conducted by over 800 students, confirmed that eclipses can generate ripples in Earth’s atmosphere called atmospheric gravity waves.

Just as waves form in a lake when water is disturbed, these waves also form in the atmosphere when air is disturbed.

This project, led by Angela Des Jardins of Montana State University in Bozeman, also confirmed the presence of these waves during previous solar eclipses.

Scientists think the trigger for these waves is a ‘hiccup’ in the tropopause, a layer in Earth’s atmosphere, similar to an atmospheric effect that is observed during sunset. 

Jie Gong, a team science expert and atmospheric scientist at NASA’s Goddard Space Flight Center in Greenbelt, Maryland, said: “Half of the teams had little to no experience ballooning before the project, but their hard work and research was vital in this finding.”