Earth's magnetic field

related topics
{math, energy, light}
{island, water, area}
{line, north, south}
{ship, engine, design}
{acid, form, water}
{land, century, early}
{specie, animal, plant}
{service, military, aircraft}
{style, bgcolor, rowspan}

Earth's magnetic field (and the surface magnetic field) is approximately a magnetic dipole, with the magnetic field S pole near the Earth's geographic north pole (see Magnetic North Pole) and the other magnetic field N pole near the Earth's geographic south pole (see Magnetic South Pole). This makes the compass usable for navigation. The cause of the field can be explained by dynamo theory. A magnetic field extends infinitely, though it weakens with distance from its source. The Earth's magnetic field, also called the geomagnetic field, which effectively extends several tens of thousands of kilometres into space, forms the Earth's magnetosphere. A paleomagnetic study of Australian red dacite and pillow basalt has estimated the magnetic field to be at least 3.5 billion years old.[1][2]

Contents

Importance

Earth is largely protected from the solar wind, a stream of energetic charged particles emanating from the Sun, by its magnetic field, which deflects most of the charged particles. Some of the charged particles from the solar wind are trapped in the Van Allen radiation belt. A smaller number of particles from the solar wind manage to travel, as though on an electromagnetic energy transmission line, to the Earth's upper atmosphere and ionosphere in the auroral zones. The only time the solar wind is observable on the Earth is when it is strong enough to produce phenomena such as the aurora and geomagnetic storms. Bright auroras strongly heat the ionosphere, causing its plasma to expand into the magnetosphere, increasing the size of the plasma geosphere, and causing escape of atmospheric matter into the solar wind. Geomagnetic storms result when the pressure of plasmas contained inside the magnetosphere is sufficiently large to inflate and thereby distort the geomagnetic field.

Full article ▸

related documents
Van Allen radiation belt
Comet Hyakutake
Fundamental interaction
Dipole
Exotic matter
Hubble's law
Electric current
Electric potential
Accretion disc
Celestial mechanics
Asteroid
Interstellar medium
Tidal locking
Mass
Quantum chromodynamics
Michelson–Morley experiment
Antimatter
Gravitational redshift
Trans-Neptunian object
Antiparticle
Latitude
Muon
Sirius
Viscometer
Space science
Elastic collision
Relative density
Centimetre gram second system of units
Magnetometer
Dyson sphere