Dramatic changes in the solar wind alter the structure and dynamics of the magnetosphere. An example of such changes allows us to look at the behavior of other cosmic bodies, such as the moons of Jupiter and the outer planets.
Scientists have reported unprecedented observations of a rare phenomenon produced by a coronal mass ejection (CME). CMEs typically propagate faster than the Alfvén speed, which is the speed at which vibrating magnetic field lines move through a magnetized plasma, which can vary with the plasma environment. in 2023 the CME that occurred disrupted the normal configuration of the Earth’s magnetosphere for about 2 hours. To find out what happened, scientists analyzed data collected by NASA’s Magnetospheric Multiscale Mission (MMS).
in 2023 April 24 The MMS spacecraft observed that while the speed of the solar wind stream was high, the Alfvén speed during strong CMEs was even higher. Normally, the solar wind moves faster than the Alfvén speed. As a result of this anomaly, the “buffer” of the Earth’s magnetosphere temporarily disappeared, allowing the Sun’s plasma and magnetic field to interact directly with the magnetosphere. The tail of Earth’s “wind sock” was replaced by structures called Alfvén wings, which connected Earth’s magnetosphere to the recently erupted region of the Sun. This junction acted as a highway for transporting plasma between the magnetosphere and the Sun.
The authors of the study write that this unique CME event has provided a new understanding of how Alfvén wings form and evolve. A similar process can occur around other magnetically active bodies in the solar system and universe – and the researchers’ observations suggest that the auroras of Jupiter’s moon Ganymede may also be caused by Alfvén wings.
The authors suggest a future search for similar Alfvén wing auroras on Earth.
The study is published žurnale „Geophysical Research Letters“.
Parengta pagal „Live Science“.
2024-08-07 18:36:43