I read this in a published scholarly article: "...deploying a magnetic shield could enhance Mars' atmosphere and facilitate crewed missions there in the future..." It made me wonder if it is possible to shield a home, basement, or room from a coronal mass ejection using an electromagnetic shield?

This question is not about and or limited to the Sun, Earth, and astronauts. Electromagnetic waves, from radio to X-ray, are constantly dealt with every day on Earth and this question explores manipulating said waves of the entire spectrum. I am particularly interested in canceling any, or all, waves instead of using Faraday cages or thick materials such as water, lead, cement, etc.

note: This question was migrated here from the Electrical Engineering SE site without asking if I would like to edit it to make it more clear. This does not make sense to me, but I do hope the people here would be more able to give better insight.

  • $\begingroup$ Earth's magnetic field is not very strong, but it manages to deflect the sun's radiation so that it passes around the earth .... the angle of deflection is quite small, if you think about it .... you would probably need a really powerful magnet to turn the radiation away from a room ... maybe an MRI type magnet .... i really do not know .... just thinking outloud .... i mean, there are machines on earth that already do something like that ... a cyclotron is one example $\endgroup$
    – jsotola
    Jun 23, 2019 at 17:52
  • $\begingroup$ There is no chance to deflect electromagnetic waves, from radio to X-ray with magnetic shields. Only radiation of charged particles. But a huge magnetic field is needed just like the field of Earth. $\endgroup$
    – Uwe
    Jun 23, 2019 at 20:50

1 Answer 1


Ionizing radiation can be both charged particles and electromagnetic radiation. As pointed out in comments, a magnetic field can in some cases be used to deflect charged particles like protons and electrons, but not electromagnetic radiation like UV light, X-rays or gamma rays.

For ionizing charged particle radiation the Earth's magnetic field is low in strength, but very large (tens of thousands of kilometers) so it can do a pretty good job of slowing down and deflecting the charged particles in a coronal mass ejection or other sources. Some is deflected towards the Earth's poles and some passes around the Earth and continues into space.

But for us on Earth we also receive a major amount of shielding by the thickness of the Earth's atmosphere! The amount of atmospheric mass above us is about the same as being 10 meters under water (or 760 millimeters under mercury). This is why people who work in commercial aviation and spend a lot of time at cruise altitude receive more radiation than the rest of us.

For ionizing electromagnetic radiation such as gamma rays, X-rays, and ultraviolet light, magnetic fields by themselves do not provide any shield whatsoever. That only comes from the electrons and to some extent nuclei in the mass of Earth's atmosphere, or thick radiation shielding provided by concrete, rock, or water for example. The wavelengths are extremely small (shorter than visible light) and so the spacing between the wires of a Faraday cage would be huge in comparison, so no Faraday cage can work for ionizing EM radiation.

For non-ionizing electromagnetic radiation such as microwaves and radio waves, Faraday cages can work if the spacing between wires is smaller than a fraction of a wavelength of the EM radiation. So the metal grid in the window of a microwave oven allows us to see the food in visible light, but shields the outside from the microwaves inside.

  • 1
    $\begingroup$ Thank you. You also answered another question I just thought about involving protection from immediate nuclear disaster and/or explosion from nuclear decay, radioactivity, nuclear radiation, isotopes, radioiodine, etc. $\endgroup$
    – Arrrstin
    Jun 24, 2019 at 23:23
  • $\begingroup$ @Arrrstin it's certainly an interesting question, and I'm glad it ended up in a more appropriate SE site! $\endgroup$
    – uhoh
    Jun 24, 2019 at 23:32

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