Stellar Fireworks: Illuminating the Cosmic Ballet of Solar Flares and Earthly Echoes

Team Udayavani, Jan 6, 2024, 2:04 PM IST

Solar flares are massive bursts of electromagnetic energy that erupt from the sun’s surface. The strength of these explosions categorizes them into different types. The strongest are known as X-class flares, with M-, C-, and B-class being progressively less intense. The least powerful category is A-class flares.

According to the University Corporation for Atmospheric Research (UCAR), these flares appear as bright flashes on a specific part of the sun and can last for a few minutes..

Solar flares happen when there’s a buildup and sudden release of magnetic energy in the sun’s atmosphere. These events are closely related to the solar cycle, which is an 11-year period of changing solar activity caused by the sun’s magnetic field.

What Leads to the Formation of Solar Flares?

The surface of the sun is filled with mixed magnetic activity.

According to NASA, magnetic fields on the sun are formed when electrically charged gases create electrical currents, acting like a magnetic generator inside the sun.According to NASA Space Place, these magnetic fields get twisted, tangled, and rearranged because of the restless behavior of the gases that form them.This restless activity of the sun’s magnetic field, also called solar activity, can cause eruptions of solar flares from the sun’s surface. These eruptions release huge amounts of electromagnetic radiation, which is a type of energy that covers radio waves, microwaves, X-rays, gamma rays, and visible light.

Solar flares usually start in areas of the sun’s surface that have sunspots. These are darker and cooler areas where the magnetic fields are very strong. Therefore, the more sunspots there are, the higher the chance of a solar flare happening.

According to the Space Weather Prediction Center of the National Oceanic and Atmospheric Administration (NOAA), the sun goes through an 11-year cycle of activity. When there are lots of sunspots, it’s called a solar maximum, and when there are few or no sunspots, it’s a solar minimum. During times of low solar activity, when there aren’t any sunspots, solar flares are unlikely to happen.

Solar Flares Today

We are currently in solar cycle 25, and solar activity is increasing. The peak of this cycle, or solar maximum, is expected in 2025. To check if there’s a solar flare today and to stay updated on the latest space weather, you can visit SpaceWeatherLive.com. This site tracks the last 24 hours of solar X-ray data from the main GOES-16 satellite and shows this information in easy-to-understand graphs. It also gives the likelihood of different types of solar flares occurring.

According to NOAA, solar flares are categorized into five classes based on the strength of X-rays they emit. Each class, represented by a letter, signifies a tenfold increase in energy output. This system is similar to how the Richter scale measures the magnitude of earthquakes.

NASA explains that X-class flares are the strongest type of solar flares. Following these are M-class flares, which are 10 times less powerful than X-class. After that come C-class, B-class, and finally A-class flares, which are the weakest and don’t really impact Earth much.

Each letter category for solar flares also has a number scale from 1 to 9. This helps to more accurately measure how strong a flare is within its class, with larger numbers indicating more powerful flares.

Unlike other classes, X-class flares can exceed the nine-point scale because they are the most powerful type and there’s no higher category. NASA reports that in 2003, a solar flare was so intense that it overwhelmed the sensors tracking it. The sensors recorded it as an X28 flare before they stopped working.

Luckily, X-class flares happen, on average, around 10 times a year, and flares as strong as the one in 2003 are even rarer.

How Do Solar Flares Impact the Earth?

Various kinds of flares, especially the powerful X-class ones, can impact the Earth, satellites, and astronauts.

Fortunately, A and B-class solar flares, which are the weakest types, occur most frequently and are too mild to significantly impact Earth. C-class flares are also quite weak and usually have little to no effect on our planet, as noted by SpaceWeatherLive.com.

When it comes to the two biggest classes of solar flares, the situation becomes more intriguing.

Powerful M-class and X-class flares can cause coronal mass ejections, which are big bursts of plasma and magnetic field from the sun. This can disturb Earth’s magnetic field, leading to geomagnetic storms. These storms can make auroras, usually seen near the poles, appear closer to the equator than they would under normal conditions.

In 1989, a significant solar flare along with a coronal mass ejection struck Earth, leading to a 12-hour electrical blackout across Quebec, Canada, as stated by NASA. This solar event caused a geomagnetic storm on Earth, which made the aurora borealis, or northern lights, visible as far south as Florida and Cuba.

Solar radiation storms release high-energy, fast-moving particles that can be harmful to astronauts and spacecraft orbiting the Earth. When these storms occur, astronauts on the International Space Station must take cover, and any spacewalks are stopped. Also, systems on satellites that are sensitive to radiation are shut down until the storm is over.

During their eruptions, M-class and X-class flares can lead to small to large radio blackouts on the Earth’s side facing the sun. These blackouts mainly disrupt High Frequency (HF) radio communications, which are between 3-30 MHz, but sometimes Very High Frequency (VHF) communications, ranging from 30-300 MHz, and even higher frequencies can be affected, as explained by SpaceWeatherLive.

Radio blackouts happen because there are more electrons in the lower part of Earth’s ionosphere, which is the layer of the atmosphere that radio waves travel through. This increase in electrons makes the radio waves lose more energy as they move through this layer, stopping them from reaching the upper layers that would normally bounce the signals back down to Earth.

Radio blackouts are the most frequent space weather events that impact Earth, with about 2,000 minor occurrences in each solar cycle.

The intensity of radio blackouts is based on the solar flare’s strength and is rated from R1 to R5 on the NOAA Solar Radiation Storm Scale, as noted by the South African National Space Agency. R1 indicates a minor event, while R5 is considered extreme. An R5 event can cause radio blackouts across the entire sunlit side of Earth and these can last for several hours. Fortunately, we typically have less than one R5 event in each solar cycle on average.

Solar Flare Prediction

The radiation from solar flares moves at the speed of light, taking just over 8 minutes to get from the sun to Earth. This means we have a very short time to react to these bursts.

Forecasting space weather is challenging, yet our capability to predict it has gotten better in recent years.

Strong solar flares can have a big impact on space vehicles, satellites, and technologies on Earth, and they often happen without much warning. Many groups, like NASA, NOAA, and the U.S. Air Force Weather Agency (AFWA), are closely observing the sun to track these flares and the magnetic storms they cause.These groups can alert technology industries that are at risk from solar flare activities, allowing them to take necessary protective measures.

NASA states that even the most intense solar flares cannot physically destroy the Earth.

Girish Linganna
Aerospace & Defense Analyst

(The author of this article is a Defence, Aerospace & Political Analyst based in Bengaluru. He is also Director of ADD Engineering Components, India, Pvt. Ltd, a subsidiary of ADD Engineering GmbH, Germany. You can reach out to him at: [email protected])