A total eclipse of the Sun is a special occurrence.

The last time that the Sun and Moon lined up perfectly for a total eclipse traversing the U.S. was in 2017; another one is due on April 8, 2024, crossing the country from Texas to Maine.

While millions of Americans gaze at the sky in wonder, scientists will be hard at work.

Because a total eclipse—by blocking the Sun itself—gives us the rare chance to study its corona, the fiery heated “atmosphere” around it, from within the path of totality.

And there are still many mysteries to unravel.

For instance, the surface temperature of the Sun is 5,500 degrees centigrade. Yet the corona is far hotter, up to 20 million degrees. How could this be possible?

One study will fly a NASA high-altitude research plane along the path of the eclipse, using spectrometers and high-resolution infrared cameras to record the temperature, structure and chemical composition of the corona—and of coronal mass ejections, or solar flares—to increase our understanding of the solar winds that reach Earth and affect our weather.

And NASA needs your help. Visit the NASA website and download the SunSketcher 2024 app. They’re hoping thousands of Americans will take photos of the total eclipse with their phones, which NASA will process and add to its study. With that simple action, you’ll become a citizen scientist.