Understanding solar flares: How explosions on Sun’s surface can lead to radio blackouts

Subject :Science and technology

Section: Space technology

Context:

The Sun emitted an X-class solar flare on July 2, 2023, disrupting radio communications over parts of the United States and the Pacific Ocean, according to media reports.

Details:

The flare, classified as an X1.0 flare, peaked at 7:14 pm ET.
X-class denotes the most intense flares, while the number provides more information about its strength.
A sunspot — a huge dark patch — known as AR3354 appeared on the solar surface and reached its maximum size on June 29, generated a significant M-class flare, and then was calm until July 2, when it unleashed an X-class flare that was directly targeted at Earth.
Initially, researchers thought the flare might have triggered a coronal mass ejection (CME) — a fast-moving cloud of magnetised plasma.
- A geomagnetic storm, or substantial disturbance of Earth’s magnetic field, would probably result from a CME from a flare of this size striking the planet.
If a huge geomagnetic storm like the one in 2003 occurred today, it would result in prolonged outages of the electrical power grid, resulting in widespread electrical disruptions, blackouts and devastation.
The most powerful flare on record was in 2003, during the last solar maximum. It was so powerful that it overloaded the sensors measuring it.

What are solar flares?

A solar flare is a tremendous explosion on the Sun that happens when energy stored in ‘twisted’ magnetic fields (usually above sunspots) is suddenly released.
There are five different classes of solar flares: A, B, C, M, and X; each class is at least ten times more potent than the one before it.
Solar flares are large energy explosions that can affect radio communications, power grids and navigation signals and endanger astronauts and spacecraft.
They can heat a substance to several millions of degrees in a matter of minutes, producing a burst of radiation that spans the electromagnetic spectrum, from radio waves to x-rays and gamma rays.
Solar flares cause energy particles to be released into space and directly impact the ionosphere and radio communications at the Earth.
Therefore, to understand and predict space weather and the effect of solar activity on the Earth, an understanding of both CMEs and flares is required.

Classification of solar flares:

Solar flares can be divided into various categories based on their brightness in X-ray wavelengths.
- X-class flares are large, significant events that have the power to cause global radio blackouts and persistent radiation storms in the upper atmosphere.
- Medium-sized M-class flares typically result in brief radio blackouts that affect the Earth’s polar regions.
- Sometimes an M-class flare is followed by small radiation storms.
- C-class flares are slight and have little effect on the Earth.

Other important terms:

Geomagnetic storms: A geomagnetic storm refers to the disruptions to the Earth’s magnetic field caused by solar emissions.
- When a Coronal Mass Ejection (CME) or a high-speed solar stream reaches our planet, it slams into the
- The Earth’s magnetosphere is created by its magnetic fields and it usually protects us from the particles emitted by the Sun.
Coronal mass ejection (CME): large-scale eruptions of charged particles (plasma) and magnetic fields from the solar atmosphere into space. They can disrupt a range of ground- and space-based technologies and satellites on Earth.
Solar cycle: The solar cycle, also known as the solar magnetic activity cycle,sunspot cycle, or Schwabe cycle, is a nearly periodic 11-year change in the Sun’s activity measured in terms of variations in the number of observed sunspots on the Sun’s surface.
- Over the period of a solar cycle, levels of solar radiation and ejection of solar material, the number and size of sunspots, solar flares, and coronal loops all exhibit a synchronized fluctuation from a period of minimum activity to a period of a maximum activity back to a period of minimum activity.