The 2024 eclipse provided a rare view of the sun. Here’s a look at the early data

WASHINGTON, DC — Scientists threw everything they had into the sky during the solar eclipse that engulfed much of the United States on April 8, 2024. They deployed high-altitude planes, recruited volunteers to release weather balloons and capture bright halo images of the sun’s corona, and sent ham radio signals back and forth through the atmosphere.

The goal was to get closer to unraveling some of the sun’s enduring mysteries, including why the corona, the sun’s outer atmosphere, is so much hotter than the surface (SN: 5/1/24).

Preliminary results from this set of solar eclipse science experiments were presented Dec. 10 at the annual meeting of the American Geophysical Union. As clouds obscured part of the eclipse’s path across the United States, teams were able to gather data that will fuel future investigations. Here’s a closer look at how some of those moon-shadowing projects fared.

Using the total solar eclipse to see the crown

A pair of NASA WB-57 aircraft set out to study the corona by flying inside the moon’s shadow along the path of the total eclipse. The spacecraft carried two types of instruments: cameras to capture images of the corona, and spectrometers that measured different wavelengths of light and could track different structures within the corona based on their temperatures.

While some images from the wing-mounted cameras were blurry due to sudden vibrations, the team was still able to capture detailed images of the corona. The spectrometers, mounted in the nose of the aircraft, were not affected.

Meanwhile, stationed along the path of totality from Texas to Maine, 35 observing teams captured images of the sun’s corona from the ground as part of the Citizen CATE (Continental Eclipse Telescopic-America) project. The goal was to put together a 60-minute movie covering the evolution of the corona during that time, said Sarah Kovac, the project leader and an astronomer at the Southwest Research Institute in Boulder, Colo.

The elusive middle corona is the transition zone between the sun’s surface and the heliosphere; it is also the origin of bursts of charged particles that can head toward Earth, potentially disrupting power grids and satellite and radio communications. Normally, it is too faint to see with telescopes. But the moon’s shadow acts as a natural coronagraph, making details visible, Kovac said.

The project was hampered by cloudy weather for much of the trail. However, the teams were able to capture over 47,000 images of the corona. A preliminary film pieced together from images collected in three different locations – in Texas, Missouri and Maine – showed how different parts of the corona were exposed over time.

Using the solar eclipse to probe gravitational waves

Elsewhere along the path of totality, more than 800 students, organized into teams, released weather balloons into the sky. The hope of the Nationwide Eclipse Ballooning Project was to catch evidence that an eclipse disturbs the atmosphere enough to create ripples called gravity waves (SN: 4/8/24). Storms and air moving over mountains are known to disturb the atmosphere enough to cause gravity waves. And the researchers suspected that an eclipse could also be a trigger, producing a sudden cooling that briefly changes the balance of the atmosphere.

A similar effect is seen at sunset every day, said Jie Gong, an atmospheric scientist with NASA’s Goddard Space Flight Center in Greenbelt, Md., who worked on the project. The stable boundary layer between Earth’s lowest atmospheric region, the troposphere, and the next region up, the stratosphere, sinks as the sun sets.

Data from a similar campaign during an October 2023 eclipse seen in the western United States showed that the eclipse had indeed sent ripples through the atmosphere, Gong said. Data collection for 2024 was somewhat hampered by cloudy weather, although each team playfully released a balloon every hour for 30 hours.

But student surveys after the project ended showed at least one clear success, Gong said: Before the project, few saw themselves as skilled in STEM fields. After participating in the project, almost everyone reported seeing themselves as good at STEM.

Animation of what happens in the ionosphere during a total solar eclipse

More than 6,350 amateur radio operators at hundreds of stations across the United States participated in a study of the eclipse’s effects on Earth’s ionosphere, the charged layer of the atmosphere where radio signals can transmit over long distances (SN: 13.8.17).

The event was organized by HAMSci, a citizen science initiative that brings together the ham radio community with space scientists, taking advantage of how radio signals bouncing off the ionosphere can provide insights into the height, density and structure of that layer. atmospheric. And that, in turn, could help researchers better understand the connection between space and the upper atmosphere, said group founder Nathaniel Frissell, a space physicist at the University of Scranton in Pennsylvania.

During the eclipse, HAMSci volunteers transmitted over 52 million signals at frequencies from 1 to 30 megahertz. What they saw, Frissell said, was that as the moon’s shadow passed, there was a drop in electron density in the ionosphere. This causes radio waves to “blow off into space and drop communications.” This effect mimics the decline in ionization that occurs each day as day turns to night, Frissell added.

The transient change in ionization due to the eclipse briefly improved communications sent at lower frequencies and degraded radio signals sent at higher frequencies, the team found. The data also revealed that the base of the ionosphere rose in height during the eclipse, and then returned to its normal height.

Probing solar mysteries from space

While total solar eclipses open the door for many people—including citizen scientists—to search for clues to the sun’s mysteries, they offer only a snapshot. More answers may come from new space-based ways to study the sun’s atmosphere.

NASA’s Parker Solar Probe has plunged into the sun’s atmosphere, searching for the source of the solar wind (SN: 6/7/23). The spacecraft will make its closest approach to the sun on December 24, when it will fly within 6.1 million kilometers of the surface.

Meanwhile, the European Space Agency’s newly launched Proba-3 mission aims to use a pair of spacecraft flying in formation to simulate hundreds of solar eclipses to better study the middle corona (SN: 12/5/24).