The Earth’s magnetosphere blocks two similar forms of radiation: the solar wind and cosmic rays. Both are high-energy, electrically charged particles that can cause severe damage to living tissues. Under most conditions, the magnetic field surrounding the Earth keeps this radiation in check. Although solar flares produce colorful auroras and disrupt some radio communications on Earth, the magnetosphere prevents harmful effects on living things.
A Magnetic “Umbrella”
Cosmic rays and the solar wind consist of particles such as protons and the nuclei of atoms. Because they have an electrical charge, the magnetic field surrounding the Earth deflects most of them as an umbrella deflects rain; the particles do not pass through the magnetosphere but bounce off or become trapped along the magnetic field lines.
Danger to Astronauts
The magnetosphere extends up to about 58,000 kilometers (36,000 miles) beyond the Earth; however, astronauts occasionally venture to places where the magnetosphere is weak or doesn’t reach at all. Outside the protective magnetic field, cosmic rays and solar wind pose health risks, making radiation a serious problem for manned space missions.
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