A new study reveals that a solar eclipse over the North Pole has caused changes in the aurora borealis in both hemispheres due to connections across the planet’s magnetic field.
The new work could help scientists predict changes in the near-Earth environment that could interfere with satellite communications.
On June 10, 2021, the moon’s shadow darkened a large part of the Earth’s north polar region, giving scientists an unprecedented opportunity to explore the effects of natural events in the scope of Earth’s space (Geospace), thousands of kilometers above Earth.
The eclipse affected the aurora borealis in both the northern and southern hemispheres, according to the new study, published in the journal AGU Geophysical Research Letters.
The aurora borealis are the twinkling light in the sky that ignites when solar storms release energy and particles that interact with gases in the atmosphere.
Some of these particles travel along Earth’s magnetic field lines to the poles, creating the northern lights in the northern hemisphere and the southern lights in the south.
“Interestingly, we found that the aurora and upper atmosphere are turbulent in the southern hemisphere where the eclipse was not covered. This is because the upper atmosphere in both hemispheres is connected by magnetic field lines and magnetosphere,” said Tong Dang, from the University of Science and Technology in China.
The results of the new study represent the first time that scientists have shown how eclipses affect coupling between the ionosphere, the regions where energy from the Sun ionizes the atmosphere and where auroras occur, and the magnetosphere, the bubble around Earth created by Earth’s magnetic field.
Dang and his colleagues discovered that the eclipse not only altered the local atmosphere under the moon’s shadow, but also caused rings to form around the poles in currents in the ionosphere and altered aurora activity in both hemispheres.
The rings are the result of disturbances in the electron density in the atmosphere caused by the charged particles of the aurora borealis.
The new research improves scientists’ understanding of the Earth’s space environment and could help researchers predict the effects of eclipses in the future.
This study also demonstrates the significant impact of a solar eclipse on the ionosphere, which can absorb, bend and reflect radio signals used by GPS satellites, potentially leading to disruptions in communication and navigation.
Geospace is defined as the area around the Earth that covers the upper atmosphere to the edges of the Earth’s magnetic field. It includes the ionosphere, which consists of regions of the upper atmosphere with large numbers of electrically charged ions and electrons. These charged particles occur when energy from the sun cuts electrons from gas molecules in the atmosphere, so their numbers increase during the day and decrease at night.
Previous studies showed that a solar eclipse can also reduce the density of particles in the ionosphere in the shadow’s path.
Dang and his collaborators developed a model that combines the upper atmosphere, magnetosphere and electric currents flowing in this system and used it to understand how the June solar eclipse affects Earth’s geographic space.
The current system in the ionosphere is complex, so the researchers focused in particular on the currents flowing between the magnetosphere and the ionosphere along magnetic field lines. These lines extend from the South Pole, around the planet to the North Pole, and then down through its axis.
They were surprised that the eclipse caused stronger auroral activity in the unobstructed southern hemisphere than in the northern hemisphere. Observers can see these changes in the aurora borealis.