A strong solar flare ripped off the tail of the Earth's magnetosphere for a few hours
In April 2023, a powerful solar flare temporarily tore off the tail of the solar magnetosphere. During those two hours, the Earth's bow shock temporarily disappeared.
The event occurred on April 24, 2023, but the details are now being known. The truth is that a massive disturbance in the solar wind caused the Earth's magnetosphere to fly without its usual tail. Let's take steps to tell what has happened.
First we must say that the Earth is constantly being hit by impacts of high-speed winds, a stream of charged particles that arrive from the Sun. As Live Science reveals, these solar wind currents curve around the Earth's magnetic field, known as the magnetosphere.
The fact that the results of the study are now known occurred in April 2023 and kept the Earth for about two hours without the total shield of protection provided by the magnetosphere.
The magnetosphere has a side that faces the Sun that is known as a shock arc that stretches until it is transformed into a long tail on the opposite side, that is, the night side. The solar wind undergoes changes, sometimes drastic, and alter the structure and dynamics of the magnetosphere. Looking at space, what happens in other bodies such as the moons of Jupiter and on exosolar planets help to understand this type of process.
Now, a recent study carried out by scientists from NASA Goddard Space Flight Center, based in Greenbelt (Maryland - USA) has reported the result of unprecedented observations of this rare phenomenon created during a coronal mass ejection (CME). This survey shows the importance of this outer layer of our atmosphere that protects us from very dangerous radiation.
Two hours of less protection
CME usually travel faster than the speed at which vibrating magnetic field lines (Alfvén speed) move through magnetized plasma, which can vary depending on the plasma environment. A CME in 2023 altered the normal configuration of the Earth's magnetosphere for approximately 2 hours. The researchers analyzed the observations of NASA's Magnetospheric Multiscale Mission (MMS) to find out what happened.
Specifically, on April 24, 2023, the MMS space probe observed that, although the speed of transmission of the solar wind was fast, the speed of Alfvén during the intense ejection of coronal mass was even higher. Normally, the solar wind travels faster than the speed of Alfvén. This anomaly caused the Earth's shock arc to temporarily disappear.
This situation allowed the plasma and the magnetic field of the Sun to interact directly with the magnetosphere. The tail of the Earth's wind sleeve was replaced by structures called Alfvén wings that connected the Earth's magnetosphere with the region of the Sun that had recently erupted. This connection acted as a highway that transported plasma between the magnetosphere and the Sun.
More observations to understand the process
The authors managed to describe this very special event of CME, and gained new knowledge about how the wings of Alfvén are formed and evolved. A similar process could occur around other magnetically active bodies in our solar system and the universe, and the observations of the researchers suggest that the formation of auroras in the moon of Jupiter, Ganymede, can also be attributed to the wings of Alfvén.
They also suggest that future work could look for similar Alfvén's wings auroras that occur on Earth. This situation also shows how vulnerable the protection that the magnetosphere gives us from the radiation that comes from the Sun is.
In the summary of the work, the team led by Li-Jen Chen of the Goddard Space Flight Center, indicates that "the reported measurements expand our knowledge about the interaction of CME with planetary magnetospheres and open up new opportunities to understand how subalf-venic plasma flows impact astrophysical bodies such as Mercury, the moons of Jupiter and the exoplanets close to their host stars."
It must be said that the Earth's magnetosphere is not the only one in the solar system. Other planets such as Mercury, Jupiter, Saturn, Uranus and Neptune have a magnetosphere. On the other hand, Ganymede, one of Jupiter's moons, has a magnetic field too weak to trap the plasma of the solar wind. And Mars has a very weak surface magnetization without an external magnetosphere.
Reference of the news:
Chen, L.-J., Gershman, D., Burkholder, B., Chen, Y., Sarantos, M., Jian, L., et al. (2024). Earth's Alfvén wings driven by the April 2023 Coronal Mass Ejection. Geophysical Research Letters, 51, e2024GL108894.https://doi.org/10.1029/2024GL108894