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

Geomagnetic storms can cause power outages and affect long-range radio communications and GPS devices.

Geomagnetic storms can cause power outages and affect long-range radio communications and GPS devices.

The story so far: Space surveillance agencies have predicted that a strong geomagnetic storm is likely to hit Earth on April 14-15, 2022. The Center for Excellence in Space Sciences, India said there is a “very high probability of earth impact” due to activity triggering the phenomenon.

The Space Weather Prediction Center (SPWC) under the US government’s National Oceanic and Atmospheric Administration (NOAA) has released two geomagnetic storm watches — one for April 14 and April 15. The storm on April 14 is expected to be moderate in strength while the storm on April 15 is expected to be minor.

What is a geomagnetic storm?

A geomagnetic storm is a disturbance in the Earth’s magnetosphere, the area around the planet that is controlled by the 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 high-velocity current reaches Earth, it strikes the planet’s magnetosphere. When the sun’s incoming magnetic field is directed south, it strongly interacts with Earth’s own magnetic field that is opposite in direction, creating perturbations. The changes produced in the Earth’s magnetic field as a result of this interaction allow solar wind particles to flow along the magnetic field lines and hit the atmosphere near the poles.

Solar winds have a major influence on the shape of Earth’s magnetosphere, and variations in solar winds cause geomagnetic storms on Earth.

At the Earth’s surface, a geomagnetic storm can lead to a rapid decrease in the Earth’s magnetic field strength. This decrease can last for about 6 to 12 hours and gradually recovers over several days.

The geomagnetic storm in question was predicted after the dead sunspot AR2987 exploded, propelling a CME toward Earth. The incoming CME is forecast to create a storm categorized as G-2 or moderate.

Sunspots are dark areas on the solar surface and contain strong, shifting magnetic fields. These are formed when areas on the sun’s surface cool slightly – from about 6,000°C to about 4,200°C – due to strong magnetic fields emerging from the solar surface. Sunspots appear as dark spots against the otherwise bright sun.

What is a 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 ionized gas present on the sun while corona is the outermost part of the sun’s atmosphere.

The corona is structured by strong magnetic fields. When these fields are closed, the solar atmosphere can release sudden, violent gas bubbles and magnetic fields that form the CME. One large CME can hold a billion tons of matter. CMEs can travel at different speeds – as slow as 250 km per second to as much as 3,000 km per second.

What are the dangers of geomagnetic storms?

According to the US Geological Survey (USGS), geomagnetic storms can affect long-range radio communications and Global Positioning System (GPS) devices. These storms can also damage satellite electronics and expose high-altitude astronauts and pilots to elevated levels of radiation.

Voltage spikes due to altered magnetic activity can also affect the power supply on Earth and cause disturbances.

Geomagnetic storms are also linked to intensified northern lights visible in the sky at higher latitudes.

SOURCE – www.thehindu.com

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