What upcoming solar eclipse can teach us about Earth
On April 8, the moon will photobomb our view of the sun, creating a rare total solar eclipse that will be seen in Mexico, across the eastern half of the United States and as far north as Newfoundland, Canada. The beauty of the celestial event is enough reason to document it, but scientists have also set up projects to study its effects. Some of the projects enlist the help of eclipse viewers, including you.
While the eclipse occurs way above our heads, the effects on Earth can be very personal. The moon’s shadow reaches Earth’s atmosphere and surface. The sudden darkness affects animal behavior, including that of the humans who know it’s coming. It affects chemical reactions around us and what we can see in space.
“It’s a once-in-a-lifetime opportunity. It’s going over hugely populated areas of the U.S., and everyone should make an attempt to see it,” said Liz MacDonald, citizen science lead for NASA’s heliophysics department. Although the last total solar eclipse seen in the United States occurred in 2017, there won’t be another one until 2044.
As a viewer, you may notice a change in the sounds around you. Birds might stop chirping and crickets might start. Nocturnal owls and bats could begin to stir.
One project has equipped people to help document changes in sounds. Using specialized audio recorders, scientists and nonscientists will record cricket sounds through a project called Eclipse Soundscapes. The project revisits a similar study conducted in 1935, when a scientist put out a newspaper ad asking people to submit their observations. Near totality, for example, it was reported that crickets began chirping as if it were evening.
Park rangers at Arkansas’s Hot Springs National Park are setting up high-end recorders in the hope of capturing the sounds of endangered bats, which could help them learn about the health of the population. As long as the bats aren’t still hibernating, this could be the first time their sounds are recorded during an eclipse in the park.
“Solar eclipses are multisensory events,” said MaryKay Severino, co-founder and education director of Eclipse Soundscapes. “It’s about how are you going to experience the eclipse, and that can be done with all different senses.”
Air temperature typically plummets 10 degrees Fahrenheit during totality. Using the GLOBE Observer app, people can report temperature and clouds. The data will help NASA scientists learn more about what happens when you temporarily turn off the sun on our solar-powered Earth. Anyone can participate in the project by downloading the app.
More subtle changes — at least to the casual viewer — occur in the atmosphere, too, including layers that affect our weather. To gather information, one project led by Montana State University is sending up helium-filled balloons with scientific instruments.
Student teams from various institutions will send balloons from the ground to the stratosphere, where the ozone layer lies, to capture data. The teams aim to determine, for example, at which altitude the temperature drop is largest, as well as the lag between the drop in sunlight and a drop in surface temperature. They will also be testing how far video streaming can be reliably transmitted, by live-streaming a balloon’s ascent during the eclipse. You can watch that here.
The teams will also be studying the creation of turbulent air waves in our atmosphere, called gravity waves. They form where air is disturbed, rippling like a stone dropped in a still pond.
“When you’re in an airplane flying low over mountains, the turbulence you feel is most likely from gravity waves,” said Thomas Colligan, a scientific software developer at NASA. He and his teammates were the first to document a gravity wave created by a total solar eclipse during the 2019 event.
Gravity waves can be created by mountains, thunderstorms, explosions — and eclipses. The moon’s shadow cools the atmosphere, creating gravity waves, analogous to the bow of a ship moving through water, said Colligan.
Atmospheric gravity waves can affect temperature and atmospheric chemistry, and can create clouds. A more detailed understanding of how gravity waves work could improve weather models and forecasts.