Solar coronal mass ejections slam into Earth, changing magnetic field: Here’s why

Strong solar winds hit Earth’s magnetosphere, causing major changes in the magnetosphere. These solar winds reshape the side of the magnetosphere facing the Sun, known as the bow shock, and stretch the magnetic field into a windsock shape with a long tail on the night side.

The solar wind has changed dramatically, altering the dynamics and structure of the magnetosphere.

Powerful coronal mass ejection disrupts Earth’s magnetosphere

In an article published in Geophysical Research Letters, Li-Jen Chen and colleagues report unprecedented observations of a rare phenomenon occurring during a coronal mass ejection (CME).

Notably, CMEs move faster than the Alfvén speed, which is the speed at which vibrating magnetic field lines move through a magnetized plasma and varies with changes in the plasma environment.

In 2023, a coronal mass ejection disrupted the normal structure of Earth’s magnetosphere for nearly two hours.

The researchers analyzed observations from NASA’s Magnetospheric Multiscale Mission (MMS). On April 24, 2023, the MMS spacecraft observed that although the flow speed of the solar wind is high, the Alfvén speed observed during a strong CME is even higher. Normally, the solar wind propagates faster than the Alfvén speed.

This anomaly caused the Earth’s bow shock to temporarily disappear, allowing plasma and magnetic fields from the Sun to interact directly with the magnetosphere.

The impact of a coronal mass ejection on the tail of the Earth’s windsock

Scientists observed that the tail of Earth’s windsock was replaced by a structure called an Alfvén wing, which forms a connection between Earth’s magnetosphere and the region of the Sun that recently erupted. This connection acts like a highway, transporting plasma between the Sun and the magnetosphere.

The authors say this unique CME event provides new insights into the formation and evolution of Alvin Wing.

Similar processes may be occurring near other magnetically active bodies in our solar system and the universe. Researchers think the auroras on Jupiter’s moon Ganymede are formed by these Alfvén wings.