Many thanks to SWLing Post contributor, David Iurescia, who shares the following article via NASA:
The Aug. 21, 2017, total solar eclipse douses Umatilla National Forest in shadow, darkening the sky and rimming the horizon with a 360 degree sunset. Credit: NASA/Mara Johnson-Groh
NASA-Funded Science Projects Tuning In to ‘Eclipse Radio’ (NASA)
On April 8, 2024, a total solar eclipse will cross parts of the United States. For millions of people along the path of totality, where the Moon will completely cover the Sun, it may feel like an eerie daytime darkness has descended as temperatures drop and wind patterns change. But these changes are mild compared to what happens some 100 to 400 miles above our heads in an electrically conductive layer of our atmosphere known as the ionosphere, where the “false night” of an eclipse is amplified a hundredfold. Three NASA-funded experiments will investigate the eclipse’s effects on the ionosphere through the power of radio, a technology well suited to studying this enigmatic layer of our atmosphere.
Whether you’ve heard of the ionosphere or not, you’ve likely taken advantage of its existence. This electric blanket of particles is critical for long-distance AM and shortwave radio. Radio operators aim their transmitters into the sky, “bouncing” signals off this layer and around the curvature of Earth to extend their broadcast by hundreds or even thousands of miles.
The ionosphere is sustained by our Sun. The Sun’s rays separate negatively charged electrons from atoms, creating the positively charged ions that the ionosphere is named for. When night falls, over 60 miles of the ionosphere disappears as ions and electrons recombine into neutral atoms. Come dawn, the electrons are freed again and the ionosphere swells in the Sun’s illumination – a daily cycle of “breathing” in and out at a global scale.
A total solar eclipse is a scientific goldmine – a rare chance to observe a natural experiment in action. On April 8 the three NASA-funded projects listed below are among those “tuning in” to the changes wrought by a blotted-out Sun.
The Super Dual Auroral Radar Network, or SuperDARN, is a collection of radars located at sites around the world. They bounce radio waves off of the ionosphere and analyze the returning signal. Their data reveals changes in the ionosphere’s density, temperature, and location (i.e. movement).
The 2024 eclipse will pass over three U.S.-based SuperDARN radars. A team of scientists led by Bharat Kunduri, a professor at the Virginia Polytechnic Institute and State University, have been busy preparing for it.
“The changes in solar radiation that occur during a total solar eclipse can result in a ’thinning’ of the ionosphere,” Kunduri said. “During the eclipse, SuperDARN will operate in special modes designed to monitor the changes in the ionosphere at finer spatiotemporal scales.”
Kunduri’s team will compare SuperDARN’s measurements to predictions from computer models to answer questions about how the ionosphere responds to a solar eclipse.
While some experiments rely on massive radio telescopes, others depend more on people power. The Ham Radio Science Citizen Investigation, or HamSCI, is a NASA citizen science project that involves amateur or “ham” radio operators. On April 8, ham radio operators across the country will attempt to send and receive signals to one another before, during, and after the eclipse. Led by Nathaniel Frissell, a professor of Physics and Engineering at the University of Scranton in Pennsylvania, HamSCI participants will share their radio data to catalog how the sudden loss of sunlight during totality affects their radio signals.
This experiment follows similar efforts completed during the 2017 total solar eclipse and the 2023 annular eclipse.
“During the 2017 eclipse, we found that the ionosphere behaved very similar to nighttime,” Frissell said. Radio signals traveled farther, and frequencies that typically work best at night became usable. Frissell hopes to continue the comparison between eclipses and the day/night cycle, assessing how widespread the changes in the ionosphere are and comparing the results to computer models.
Some radio signals don’t bounce off of the ionosphere – instead, they pass right through it. Our Sun is constantly roiling with magnetic eruptions, some of which create radio bursts. These long-wavelength bursts of energy can be detected by radio receivers on Earth. But first they must pass through the ionosphere, whose ever-changing characteristics affect whether and how these signals make it to the receiver.
The RadioJOVE project is a team of citizen scientists dedicated to documenting radio signals from space, especially Jupiter. During the total solar eclipse, RadioJOVE participants will focus on the Sun. Using radio antenna kits they set up themselves, they’ll record solar radio bursts before, during, and after the eclipse.
During the 2017 eclipse, some participants recorded a reduced intensity of solar radio bursts. But more observations are needed to draw firm conclusions. “With better training and more observers, we’ll get better coverage to further study radio propagation through the ionosphere,” said Chuck Higgins, a professor at Middle Tennessee State University and founding member of RadioJOVE. “We hope to continue longer-term observations, through the Heliophysics Big Year and beyond.”
Find out more about the April 8, 2024, solar eclipse on NASA’s eclipse page.
By Miles Hatfield
NASA’s Goddard Space Flight Center, Greenbelt, Md.
I’m flying to Rochester, NY for the eclipse and planning to monitor the MW band for an hour before and after the event. I’m taking a Raspberry Pi with a 500Gb NVMe drive attached to a SDRPlay DX running SDRConnect. My question is about antennas.
Not sure where my cousins and I will be stationed but I’m sure it will be fairly close to the usual sources of noise. A magnetic loop would be normally the right choice but I want to capture the entire MW band without any additional tuning and tweaking. For the moment I’ve chosen a Deshibo GA800 amplified loop, but it picks up a lot of noise at those frequencies. Is there a better alternative that I can build or buy in the days remaining? Size matters as I’ll be flying to Rochester from California.
Thanks for any suggestions.
The New York Westchster County area will have a 89 percent cover on the sun from the moons shadow (not too Shabby) on April 8,2024 around 3 Pm EST.Hope for fair skies !
Correction that is “Around 3 Pm “(Eastern (DAYLIGHT) time”
I shared the eclipse info about HamSCI with my Ham radio club and I got crickets (no response nor any interest). It is amazing to me how dull-minded and myopic a group of supposedly very intelligent Ham radio people can be. I get the feeling that their only purpose in life is to talk endlessly about nothing on the 2 meter repeater or to participate in endless “check-ins” for nets on shortwave. So far, ZERO interest in this ostensibly once-in-a-lifetime event to hear or make contact with stations due to a fascinating scientific phenomenon (20 meter signals disappear and 40 & 80 meter signals pop-up out of nowhere for a few minutes as the dark spot passes over each station). I do know of a Ham radio club that is making a big event out of it in central Texas – good for them! If you want to hear what the 2017 event sounded like on Mediumwave, see my report here:
https://swling.com/blog/2017/08/toms-am-broadcast-band-recordings-during-eclipse-totality/
Oh, and the eclipse itself was out of this world, eerie, and cool.
Tom-
Understand your frustration. My opinion is that it is more useful =and more scientific- to compare eclipse conditions with reference conditions on stable signals (broadcast/WWV/CHU/etc.) rather than random ham contacts. My experience is that monitoring of MW signals, especially of clear channel stations, will show significant benefits. I was fortunate that the timing/trajectory of the partial eclipse over the Pacific in 2017 was such that I was able to see a tremendous positive impact on SWBC signals from Asia that had already faded out after local sunrise. I sent a complete report to HamSCI but it didn’t get any attention.
I’ve monitored several partial eclipses over the years. On one that occurred over the Eastern Pacific, signals from Asia on the lower bands (60-31mb) faded back in several hours after they would normally fade out at sunrise. During the most recent one that was partial on the West Coast, I observed that medium wave signals on the upper part of the band faded in to night time levels during the partial eclipse. Best example was on the roughly 480 mile path from KFBK 1530 Sacramento to San Diego. Diligent MW DXers should see similar DX opportunities during the upcoming total eclipse!
I’m looking forward to this event. Living near Niagara Falls, Ontario I’m told I have a front row seat. I’m interested to see what happens to propagation.