Earth’s magnetic field may be more powerful than we thought
March 25, 2026
3 min reading
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Earth’s magnetic field may be stronger than we thought
A major defense against anything space throws at us, Earth’s magnetic field could even protect the Moon from harmful galactic cosmic rays.
Although it is far from Earth’s magnetic core, the Moon feels the effects of the core even more than scientists previously thought.
Racing through the universe with incredible power and speed, galactic cosmic rays are a major source of radiation in space. But thanks to Earth’s powerful magnetic field, these charged particles generally don’t reach our planet directly, so we are protected from the harmful effects of radiation. This field could do much more: New data collected by China’s Chang’e 4 lunar lander shows that the influence of our magnetic field is so powerful that it extends further into space than previously thought, even extending beyond the Moon.
In a study published Wednesday in Scientific advances, the researchers describe a “cavity” in the space between the Earth and the Moon where cosmic rays are deflected by the Earth’s magnetic field. This suggests that the effects of our planet’s magnetism are present much further from us than might have been expected.
Gravitational cosmic rays meander through the heliosphere, but Earth’s magnetic influence shields much of space from certain particles.
Excerpted from “A Galactic Cosmic Ray Cavity in Earth-Moon Space,” by Wensai Shang et al., in Scientific advances, Flight. 12, no. 13; March 25, 2026
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Launched in 2018, Chang’e 4 was the first spacecraft to land on the far side of the Moon. Among the many scientific instruments on board was the Lunar Lander Neutron and Dosimetry experiment, designed to measure the radiation future astronauts might experience if they were to land there. Scientists had long thought that most of the Moon lay beyond the protection of Earth’s magnetic field, but in 2019, scientists began to notice something strange in the experiment’s data that suggested the Moon was somewhat shielded from galactic cosmic rays.
The discovery was “a surprise,” says Robert Wimmer-Schweingruber, co-author of the study and a physicist at the University of Kiel in Germany. “I personally didn’t believe it for a long, long time. I thought it was an artifact in the data until we did a lot of statistical testing.”
Galactic cosmic rays come from various sources in space, such as stars, supernovae and black holes. These diverse origins mean that when the rays approach the Earth, they do not all carry the same level of energy. The most energetic particles move quickly through the solar system, while some of the weaker particles persist and their radiation could affect astronauts, says Wimmer-Schweingruber.
“We weren’t really interested in these low-energy particles until we saw this effect, and then we realized that this was actually important for astronauts’ skin dose,” he says.
Protecting astronauts from the dangers of radiation is essential to guaranteeing a human presence in space. That means creating materials that are light enough to be transported into space but protective enough to keep radiation at bay, says Philip Metzger, a professor of planetary science and space technology at the University of Central Florida, who was not involved in the new study. Knowing more about the distribution of radiation in space, and particularly between the Moon and Earth, could help scientists plan safer missions.
For example, if NASA’s plan to send humans to the Moon semi-permanently comes to pass, then it might make sense for astronauts to plan activities outside of any sheltered habitat while the Moon is under the influence of Earth’s magnetic field.
“This is brilliant research, and it shows us that the more we study phenomena outside of our planet, the more we discover that we don’t know,” says Metzger. “That’s why we need to carry out space missions.”
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