Knowledge Nugget: Biggest solar storm in two decades — key facts you must know for UPSC

Why in the news?

A powerful solar radiation storm struck the earth on January 18-19, 2026. This is the strongest solar radiation storm observed in more than two decades and it has been ranked four out of five on intensity scale by the Space Weather Prediction Centre (SWPC).

According to Space.com, the Sun caused an intense X-class solar flare, the strongest in 23 years, which sent a fast coronal mass ejection (CME) hurtling toward Earth. The CME slammed into Earth’s magnetic field at around 2.38 pm EST (1938 GMT) on January 19, escalating geomagnetic conditions to G4, or “severe”, storm levels, the US National Oceanic and Atmospheric Administration’s (NOAA) SWPC reported.

In today’s knowledge nugget, let’s understand the reasons behind these solar radiations and the Northern Light display triggered by the solar storm.

Key takeaways:

1. The Sun is not a gentle, unchanging sphere. It is a churning, magnetic dynamo. Sunspots – darker, magnetically intense patches on the solar surface –  can become unstable, twist, and snap like stressed rubber bands. When this happens, the Sun can unleash enormous explosions of energy called solar flares, and massive clouds of charged particles called coronal mass ejections (CMEs).

2. The Sun follows an approximately 11-year activity cycle, and right now it is moving through the more active phase of Solar Cycle 25. The active phase of the solar cycle led to an increase in solar flares and coronal mass ejections (CME).

3. Solar flares release huge bursts of radiation and energetic particles by sudden release of magnetic energy stored in the complex solar magnetic field. In CMEs, the sun throws out large amounts of plasma and magnetic fields.

4. Solar cycle: The sun has a magnetic field with north and south poles similar to a bar magnet. The magnetic field exists due to the constant movement of electrically charged particles within the Sun.

5. Solar maximum: This solar cycle affects the activity on the surface of the Sun. For instance, the Sun is at its most active when the magnetic field flips. This phase is called the solar maximum. During this period, the star can send out more frequent and intense bursts of radiation and particles into space. After the flip, the star calms down until it reaches the solar minimum, and a new cycle begins.

Impact of Solar Storm

6. Such events can have a serious impact on space weather and geo-space, including disrupting radio communications, affecting satellite operations, interfering with power grids, and posing risks to astronauts and airline passengers.

7. Solar storms of that magnitude have caused serious problems in the past. The well-known Halloween storms of 2003 led to power outages in parts of Sweden and damage to power equipment in South Africa, the agency noted.

8. When this kind of radiation reaches Earth, it increases exposure risks for astronauts aboard the International Space Station and for passengers flying on routes that pass over the poles. Because of this, the SWPC has already alerted several key organisations, including airlines, NASA and emergency management authorities, to prepare for potential impacts.

BEYOND THE NUGGET: Northern Lights

Aurora borealis, also known as the northern lights, is seen in the sky above Nuuk, Greenland, Tuesday, Jan. 20, 2026. (AP Photo/Evgeniy Maloletka)

1. This powerful solar storm triggered by an X-class solar flare led to stunning auroral displays, also known as the Auroras or Northern Lights, visible far beyond their usual polar regions. They were reported across California, Greenland, Austria, Germany, and several other regions. In the United States, auroras were spotted as far south as Southern California, which is a rare occurrence.

2. Auroras are formed due to an active interaction in space between charged solar winds and the Earth’s magnetosphere. Solar winds are a stream of charged particles, mainly electrons and protons, and magnetic fields, released by stars.

3. As the solar wind approaches the Earth, it is deflected by the planet’s magnetic field, which acts like a protective shield. However, some of the charged particles are trapped in the magnetic field and they travel down the magnetic field lines at the north and south poles into the upper atmosphere of the Earth.

4. These particles then interact with different gases present there, resulting in tiny flashes that light up the night sky. When solar wind particles collide with oxygen, a green coloured light is produced. Interaction with nitrogen produces shades of blue and purple. It is “much like how electrons flowing through gas in a neon light collide with neon and other gasses to produce different colored light bulbs,”

5. When these bright and colourful lights are observed near the North, it is called Aurora Borealis, while those in the South are called Aurora Australis.

Post Read Question

If a major solar storm (solar flare) reaches the Earth, which of the following are the possible effects on the Earth? (UPSC CSE 2022)

1. GPS and navigation systems could fail.

2. Tsunamis could occur at equatorial regions.

3. Power grids could be damaged.

4. Intense auroras could occur over much of the Earth.

5. Forest fires could take place over much of the planet.

6. Orbits of the satellites could be disturbed.

7. Shortwave radio communication of the aircraft flying over polar regions could be interrupted.

Select the correct answer using the code given below:

(a) 1, 2, 4 and 5 only

(b) 2, 3, 5, 6 and 7 only

(c) 1, 3, 4, 6 and 7 only

(d) 1, 2, 3, 4, 5, 6 and 7

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