magnetosphere

American  

[mag-nee-tuh-sfeer] / mægˈni təˌsfɪər /

noun

Astronomy.

1. the outer region of the earth's ionosphere, where the earth's magnetic field controls the motion of charged particles, as in the Van Allen belts.

2. such a region of another planet.

   Jupiter's magnetosphere.

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magnetosphere British  

/ mæɡˌniːtəʊˈsfɛrɪk, mæɡˈniːtəʊˌsfɪə /

noun

1. the region surrounding a planet, such as the earth, in which the behaviour of charged particles is controlled by the planet's magnetic field

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magnetosphere Scientific  

/ măg-nē′tō-sfîr′ /

1. A highly asymmetrical region surrounding the Earth, beginning about 100 km (62 mi) above the surface on the side of the Earth facing the Sun and extending hundreds of thousands of kilometers into space on the opposite side. In this region the Earth's magnetic field exerts a significant influence on any charged particles that encounter it. The magnetosphere deflects most of the charged particles in the solar wind, but also traps and deflects some of these particles toward the Earth's magnetic poles, causing magnetic storms and auroras.

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Other Word Forms

• magnetospheric
  adjective

Etymology

Origin of magnetosphere

First recorded in 1955–60; magneto- + -sphere

Example Sentences

Charged particles of solar wind constantly catapult toward Earth, but most get deflected by the magnetosphere, which acts like a real-life Star Trek shield.

From The Wall Street Journal • Jul. 10, 2026

The Earth is protected from solar and cosmic particles by the magnetosphere, a region generated by the movement of molten iron in the planet’s core.

From The Wall Street Journal • Jul. 10, 2026

Earth's magnetosphere offers some protection against radioactive cosmic rays and solar particles to the orbiting ISS, but no such cover on the Moon.

From Barron's • Apr. 10, 2026

"Enceladus itself is a key driver of this environment, releasing huge amounts of water vapor that gets ionized, loading the magnetosphere with heavy plasma that is then pulled around as the planet spins."

From Science Daily • Apr. 3, 2026

Anything potent enough to put on such a show could well blow away the magnetosphere, the magnetic zone high above the Earth that normally protects us from ultraviolet rays and other cosmic assaults.

From "A Short History of Nearly Everything" by Bill Bryson