Climatology, Environment, High energy, Light, Magnetism, Space, Thermodynamics, Wireless

Solar flares: How are formed?

This post’s subject is solar flares, what are and how they form. And how it can interfere in the current communication systems.

What are and how they form?

The solar flares are very high energy explosions that usually occur next to sunspots. Which are darker and cooler regions of the photosphere.

In the sunspots, are formed intense magnetic fields. These fields store energy and are twisted, release energy due to the magnetic reconnection effect.

Formation of solar flares diagram
Source: NASA.

The magnetic reconnection occurs when two magnetic fields in the opposite direction contact each other, two new perpendicular fields are formed releasing a great quantity of energy.

These magnetic fields are generated in the Sun’s convective zone, where magnetic fluxes are formed due to plasma`s motion.


This phenomenon is only present in plasmas. Emits electrons, protons, and ions close to the speed of light and electromagnetic waves in a great frequency range, from radio waves to gamma rays.

Solar flares categories

The solar flares are classified into five categories according to radiation intensity in hydrogen-alpha (Hα) frequency.

  • Type C: Are small and don`t affect Earth, has peak flux from 10^{-6} to 10^{-5} W/m^2;
  • Type M: Medium size, hit the polar regions, and may temporarily suspend radio transmission. Peak flux is between 10^{-5} and 10^{-4} W/m^2;
  • Type X: Are the biggest, can cause radio blackouts in the entire world, and long turbulences. Whose peak flux is bigger than 10^{-4} W/m^2.

Exist the categories A and B, which are smaller than C. Type B stays between 10^{-6} and 10^{-7} W/m^2, while the type A is smaller than 10^{-7} W/m^2. Inside each category there is a linear scale, to compare the intensity of flares from the same type. For example, M2 is ten times bigger than M1.

How it affects the communications?

Solar flare
Source: Shutterstock.

Although Earth has a magnetosphere which protects against big part of radiation, hard (higher energy) X-rays from solar flares can cause damage to astronauts and spaceship’s electronic systems. The soft (lower energy) X-rays enter Earth’s ionosphere, increase the ionization of this atmospheric layer and interfere in communication satellites and GPS, which can damage its chips, and reduce lifespan.

Solar flares can’t be confused with Coronal Mass Ejections (CME), which will be subject to another post.

About Pedro Ney Stroski

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