Van Allen Radiation belt in Magnetosphere is our Earth's shield
Magnetosphere- The Magnetosphere is a magnetic layer (bubble-like) of the earth that covers the earth as a shield, of the earth, present in the outermost bounder of the earth's atmosphere. It presents after the exosphere.
Extention: Beyond 750 km to towards solar wind or earth magnetic field to solar wind.
Components: Ionised particles increase beyond 200 km from the sea level in the magnetosphere only electrons (+) and protons (-) are derived from the solar wind. Hydrogen and Helium atoms are also found.
Occurrence: In the magnetosphere, the earth's magnetism is generated by the convective currents of molten Iron and Nickel in the earth's outer core which is located in the internal part of the earth and belongs to the outer layer of the earth's Core (Innermost layer of the earth). Convective current occurs in the outer core due to the difference of Radio active heating and the presence of chemical components. These currents carry streams of charged particles and thus magnetic field occurs because convective kinetic energy is converted to electrical energy.
Characteristics: i) Structure: Solar wind compresses the magnetic field on earth's day side 65000km from the planet (10 earth radii).On the night side away from the sun, guided by the earth's magnetic field and thus magnetosphere extends a considerable distance. The tail touches the moon's orbit (1000 earth radii). ii) Magnetosheath: This is a region of maximum turbulence which is presented in between 10 to 13 earth radii towards the sun where magnitude and direction vary of the earth's magnetic field and forms a bow-shaped structure. It occurs due to high-velocity solar wind particles. Ahed of this towards sun relatively less disturbing solar wind. iii) Almost 65000 km in height from the earth's surface earth's gravity is so weak that particles are escaping but solar wind comes from its opposite direction.
Van Allen Radiation Belt: This is a doughnut-shaped magnetic field of the earth, fully present in the magnetosphere. This belt is a highly electric charged particle and most of which comes from solar particles.
The zones were named for James A Van Allen, the American physicist who discovered the belt in 1958. He gathered his knowledge from the transmitted data of Explorer Satteliten (I, III and IV). This belt is extended from 3000 km to 16000km approx. An Innerbelt was found to lie about 2300 mi (2600 km) and an outer belt at about 8000 to 12000 mi ( 13000 to 19000 km) from the earth's surface. The Outer belt is a much more intense belt.
Characteristics: i) The Van Allen belts are most intense over the equator and absent above poles (South and north pole) ii) Structure: This belt is divided into two zones.No real gaps exists between the two zones and they gradually marge with each other. The outer belt is made up of billions of high-energy particles that come from solar wind and becomes trapped in the earth's magnetic field. The Innerbelt is made from the interaction of cosmic rays with the earth.
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Observation of NASA and other countries: It was early 1958, USA had just launched its first spacecraft to observe the earth's atmosphere from 900 miles above the surface of the earth. In 1958 the USA launched the first Sattelite Explorer 1 to observe Van Allen belt. The Soviet Union also send Sputnik 1 and 2 spacecraft the same year. 60 years later in 2012 NASA send the twin Van Allen Probe to study particle behaviour in the outer belt. The probe found a void region between the outer and inner belt which is thought to be empty was occupied by a third temporary belt. In 2016, Japan Aerospace Exploration Agencies (JAXA) launched the satellite to cooperate with the Van Allen Probes to study the radiation belt. However, NASA declared that Van Allen Probe will be retired in 2019. A CubeSat mission, the compact radiation belt explorer (CERES) was scheduled to launch in 2018 to study the interaction between plasma waves and electrons in Earth's atmosphere. Collaboration between researchers from Japan, USA and Russia have observed through satellite data, a hot spot found in the earth's radiation belt where killer electrons form, which can cause serious anomalies in satellites. The finding was published in the journal Geophysical Research Letters. This could help scientists to predict accurately when killer electrons form.
Importance: Van Allen Belt protects the life of earth from high energetic charged particles coming from the sun as the solar wind causes geomagnetic storms.
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