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

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.

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.