Answer:
Earth's magnetic field deviates high energy particles (e.g cosmic rays) that are a risk for human health.
Explanation:
Cosmic rays are high energy charged particles (88% protons, 10% nuclei of helium, 1% heavier nuclei) that came from the outer space. The energies of these particles are in the range of 1 GeV to 10⁸ TeV. Since they are charged particles, they will be deviated by Earth’s magnetic field¹ (as a reminder: A magnetic field applies a magnetic force over a moving charged particle).
Earth’s magnetic field works as a shield to humans against high energy charged particles, if cosmic rays were in touch with a human body, it can break molecules that forms DNA structure². Modifying that structure can lead to diseases as cancer, for example.
Units:
GeV: Giga-electronvolt
TeV: Tera-electronvolt
¹Magnetic field: It is generated around the space of a moving charged particle.
²DNA structure: It is a compound of different molecules that provides information to cells functionality.
