What do scientists hope to learn from the total solar eclipse in the US?

When a rare total solar eclipse sweeps across North America on April 8, scientists will be able to gather invaluable data on everything from the sun’s atmosphere to strange animal behavior – and even the possible effects on humans.

It comes with the sun near the peak of its 11-year solar cycle, setting the stage for a breathtaking display: The corona will glow spectacularly from the moon’s silhouette along the path of totality, a corridor stretching from Mexico to Canada across the United States.

Total solar eclipses offer “incredible scientific opportunities,” NASA Deputy Administrator Pam Melroy said at a news conference this week about the celestial event.

The US space agency is one of the institutions preparing for the eclipse, with plans to launch so-called “sounding rockets” to study the effects on Earth’s upper atmosphere.

Here’s a look at what researchers hope to learn from the upcoming eclipse:

Sunny atmosphere

When the moon passes directly in front of the sun and blocks it, the elusive outermost edge of the sun’s atmosphere, or corona, will be visible “in a very special way,” Melroy said Tuesday.

“There are things going on with the crown that we don’t fully understand,” she said.

The heat in the corona intensifies with distance from the Sun’s surface, a counterintuitive phenomenon that scientists struggle to fully understand or explain.

Solar flares, a sudden explosion of energy that releases radiation into space, occur in the corona, as do solar bulges, huge plasma formations that erupt from the sun’s surface.

During an eclipse, the lowest part of the corona — where much of this activity occurs — is more clearly visible than when specialized instruments are used to block out the central part of the sun, offering a golden opportunity for research, said Shannon Schmoll, director of the Abrams Planetarium at Michigan State University.

Researchers are particularly excited that the sun is near the peak of its 11-year cycle.

“The chance of seeing something incredible is very high,” Melroy said.

Earth’s atmosphere

The total eclipse will also give scientists a chance to study changes in a part of Earth’s upper atmosphere known as the ionosphere, important because it affects radio waves used for communication and navigation.

“Disturbances in this layer can cause problems with GPS and communications,” said Kelly Korek, eclipse program manager at NASA Headquarters.

The ionosphere, which is where Earth’s atmosphere meets space, is affected by the sun, which electrically charges the particles there during the day.

NASA’s three sounding rockets will be launched before, during and immediately after the eclipse from Virginia to measure these changes.

The large reduction in sunlight provoked by the eclipse – faster and more localized than a normal sunset – should allow researchers to learn more about how light affects the ionosphere so that they can better predict potentially problematic disturbances.

Animal behavior

Amazing animal behavior has been observed during eclipses: giraffes have been seen galloping, while roosters and crickets can start singing and chirping.

In addition to the reduction in sunlight, temperatures and wind—conditions to which animals are sensitive—can also decrease significantly during an eclipse.

Andrew Farnsworth, an ornithology researcher at Cornell University in New York state, studies how eclipses affect birds by using weather radar to detect birds in flight.

During the last total solar eclipse visible from the United States in August 2017, scientists observed “a decrease in the number of flying animals,” Farnsworth told reporters.

The 2017 eclipse disrupted the daily activities of insects and birds, but did not trigger the animals’ usual nocturnal behavior, such as bird migration or bat emergence, the expert said.

This time, the birds may be more likely to migrate during the eclipse, given that it’s in April, he said.

“These kinds of patterns — they’re important to understanding the ways animals make sense of their worlds,” Farnsworth said.

A human miracle

“Eclipses have a special power. They make people stand in awe of the beauty of our universe,” NASA Administrator Bill Nelson told reporters.

Researchers explored this sense of awe in 2017 using data from nearly three million users of Twitter, now called X.

Those on the so-called “way of totality” tend to use the pronoun “we” (as opposed to “I”) and express concern for other people, according to Paul Piff, a professor of psychology at the University of California, Irvine.

“What we’re finding is that awe-inspiring experiences … seem to tune people and connect us to each other to connect us to beings that are bigger than ourselves,” Piff said.

This year, he plans to study whether the experience has any effect on the political divide in society.

Citizen scientists

About 40 citizen science projects are planned around the eclipse, from using a phone app to record temperature and cloud cover to recording ambient noise during the event.

“We encourage you to help NASA monitor the sights and sounds around you,” Nelson said.