According to researchers, the C and X-shaped formations are evidence that we still have much to learn about the ionosphere and its impact on communication and navigation signals passing through it.

Similar shapes have been observed before, but this time, they were noticed in places where scientists did not expect them and appeared at surprising moments. The NASA Observations of the Limb and Disk (GOLD) mission aided in the more detailed observation of the C and X-shaped formations. Its main goal is to measure density and temperature in our planet's thermosphere and ionosphere.

Mysterious shapes in the ionosphere

NASA reminds us that the ionosphere, which stretches from 50 to 600 kilometres above our heads, becomes electrically charged during the day when sunlight hits the Earth. Its energy knocks electrons out of atoms and molecules. This creates a mixture of charged particles, called plasma, which allows radio signals to be transmitted over long distances. The mentioned plasma is also influenced by the Earth's magnetic field, creating the shapes above.

"Near Earth’s magnetic equator, charged particles are funnelled upward and outward along magnetic field lines, creating two dense bands of particles north and south of the equator that scientists call crests. As night falls and the Sun’s energy fades, low-density pockets in the plasma, called bubbles, can form in the ionosphere. Because of their varying density, the crests and bubbles can interfere with radio and GPS signals," NASA explains in a press release.

solar storms and significant volcanic eruptions but also during so-called "quiet time." This suggests that local factors play a more significant role in these processes. Additionally, computer models indicate that lower atmosphere conditions are likely causing downward plasma movement.

"Earlier reports of merging were only during geomagnetically disturbed conditions - it is an unexpected feature during geomagnetic quiet conditions," said Fazlul Laskar, an ionospheric physicist from the University of Colorado.

Scientists were also surprised by the appearance of plasma, shaped like the letter C and its inverse. These formations, likely created by winds on Earth, appeared close to each other at a distance of about 630 kilometres. Observing such shapes is rare they have been noticed only twice. Consequently, scientists on the GOLD mission plan further studies to understand exactly what causes their formation. "Within that close proximity, these two opposite-shaped plasma bubbles had never been thought of, never been imaged," noted Deepak Karan, an ionospheric physicist from the University of Colorado.

The plasma in the ionosphere is crucial for long-distance radio wave transmission, and the latest discoveries help better understand how radio and GPS systems work. This is especially true since disturbances in the ionosphere, such as those observed, can affect communication and navigation infrastructure.