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A geomagnetic storm is expected to hit the earth. What is it, and how is it caused?

  • Category
    Science & Technology
  • Published
    25th Apr, 2022

Context

Space-monitoring agencies have predicted that a strong geomagnetic storm is likely to hit the earth.

  • The Centre for Excellence in Space Sciences, India said that there is a “very high probability of earth impact” due to solar activity causing the phenomenon.

About

Geomagnetic storm:

  • A geomagnetic storm is a disturbance in the earth’s magnetosphere, which is the area around the planet controlled by its magnetic field.
  • The earth’s magnetosphere protects its inhabitants from most of the particles emitted by the sun.
  • When a coronal mass ejection (CME) or a high-speed stream reaches the earth, it strikes the planet’s magnetosphere.
  • If the incoming solar magnetic field is directed southwards, it interacts strongly with the earth’s own magnetic field that is opposite in direction, causing disturbances.
  • The changes produced in the earth’s magnetic field as a result of this interaction allow solar wind particles to stream down the magnetic field lines and hit the atmosphere near the poles.
  • Solar winds deeply impact the shape of the earth’s magnetosphere, and variations in solar winds cause geomagnetic storms on earth.
  • At the surface of the earth, a geomagnetic storm can result in a rapid decline in the earth’s magnetic field strength. This decrease can last for around 6 to 12 hours and gradually recovers over several days.
  • Sunspots are dark areas on the solar surface and contain strong, shifting magnetic fields. These are formed when areas on the surface of the sun cool slightly – from around 6,000 °C to about 4,200 °C — due to strong magnetic fields that emerge through the solar surface. Sunspots appear as dark spots against the otherwise bright sun.

Coronal Mass Ejection (CME):

  • A coronal mass ejection is a large expulsion of plasma and magnetic field from the sun’s corona.
  • Plasma is the highly ionised gas present on the sun, while corona is the outermost part of the sun’s atmosphere.
  • The corona is structured by strong magnetic fields. If these fields are closed, the solar atmosphere can release sudden, violent bubbles of gas and magnetic fields which constitute the CME.
  • One large CME is capable of containing a billion tonnes of matter.
  • CMEs can travel at varying speeds – as slow as 250 km per second to as high as 3,000 km per second.

What are the hazards associated with geomagnetic storms?

  • According to the U.S. Geological Survey (USGS), geomagnetic storms can impact long-range radio communication and global positioning system (GPS) devices.
  • These storms can also damage satellite electronics and expose astronauts and high-altitude pilots to increased levels of radiation.
  • Voltage surges due to altered magnetic activity can also affect power supply on the earth and cause outages.
  • Geomagnetic storms are also linked with intensified northern lights visible in the skies of higher latitudes.

What is a Solar Storm?

  • Solar storms are magnetic plasma ejected at great speed from the solar surface.
  • They occur during the release of magnetic energy associated with sunspots (‘dark’ regions on the Sun that are cooler than the surrounding photosphere), and can last for a few minutes or hours. 
  • Solar storms can hit operations of space-dependent services like global positioning systems (GPS), radio, and satellite communications.

Types of Solar Storms:

Solar Storms come in the form of the following types:

  • Solar Flares: A solar flare is a sudden flash of increased brightness on the Sun, usually observed near its surface and in proximity to a sunspot group.
    • Powerful flares are often, but not always, accompanied by a coronal mass ejection.
    • Even the most powerful flares are barely detectable in the total solar irradiance (the “solar constant”).
  • Coronal Mass Ejection: A coronal mass ejection (CME) is a significant release of plasma and accompanying magnetic field from the solar corona.
    • They often follow solar flares and are normally present during a solar prominence eruption.
  • Geomagnetic Storm: A geomagnetic storm is a major and temporary disturbance of Earth’s magnetosphere.
    • They occur when a surge of solar wind (charged particles from the sun) interacts with Earth’s magnetic field and generates charged particles and currents in Earth’s upper atmosphere.
    • Geomagnetic storms interfere with high-frequency radio communications and GPS navigation systems. Aircraft flights, power grids, and space exploration programmes are vulnerable.
  • Solar Particle Events: A solar particle event or solar proton event (SPE), occurs when particles (mostly protons) emitted by the Sun become accelerated either close to the Sun during a flare or in interplanetary space by coronal mass ejection shocks.
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