A solar phenomenon caught the attention of the scientific community at the beginning of December. Between the 4th and 5th, a gigantic spot of around 800 thousand kilometers long, the size of 60 Earths, appeared on the surface of the Sun, indicating the presence of a geomagnetic storm, which, depending on its intensity, could cause damage to the magnetic field. from the earth.
The scientists’ surprise came because the spot, known as a coronal hole, appeared at a time when the Sun is reaching the peak of its 11-year cycle, known as solar maximum, which should occur in 2024. According to the Sun Prediction Center Space Weather, from the United States Oceanic and Atmospheric Agency (NOAA), these phenomena tend to appear larger and more frequently at solar minimum, when activity is lower in the star.
In the image released by NASA’s Solar Dynamics Observatory (American space agency), the spot appears as dark areas in the solar corona. However, they are only visible through optical devices that show extreme ultraviolet rays (EUV) and soft X-rays.
According to NOAA, they appear dark because they are colder and less dense regions than the surrounding plasma and are regions of open magnetic fields, which allow the solar wind to escape more easily and at greater speed into space, resulting in known currents. as high speed.
American scientists predicted that this geomagnetic storm could reach intensity level G2, which could cause damage to transformers on the Earth’s surface and interfere with the control of spacecraft, for example. However, he was at the lowest level (G1).
The only effect visible to humans is the aurora borealis, the bright, colorful clouds that normally appear at the planet’s poles, but which, depending on the intensity of the geomagnetic storm, can be seen at increasingly lower latitudes, i.e. closest to the equator.
For a better understanding by ordinary people, NOAA created a scale of geomagnetic storms, with five levels: G1 (minor), G2 (moderate), G3 (strong), G4 (severe) and G5 (extreme). The stronger the intensity, the rarer the phenomena during the 11-year solar cycle.
The last large coronal hole to appear on the Sun was in March this year. That one, however, triggered a geomagnetic storm that peaked at a G4 level, surprising experts. The unexpected strength of the storm not only made the auroras visible as far as New Mexico, in the US, but also forced spaceflight company Rocket Lab to postpone a rocket launch for 90 minutes, according to Space.com.
According to The Washington Post, the two largest geomagnetic storms on record occurred in 1859 and 1921. The first, which became known as the Carrington Event, in September of that year, caused auroras as far as Tahiti, which is just 1,950 kilometers from the equator. And electricity spikes paralyzed the world’s telegraph systems, interrupting messages.
The other occurred in May 1921, interrupting and damaging the telephone and telegraph systems in the United States and European countries. There are reports of telegraph stations catching fire after being hit by the storm. The aurora was seen in the US state of California.
Check out the impacts of geomagnetic storms on Earth:
G1 (smallest) – frequency of 1,700 cases per 11-year cycle of the Sun
- power systems: Weak fluctuations in the power grid may occur.
- Space operations: Possible minor impact on satellite operations.
- Other systems: Migratory animals are affected at these levels and above; Aurora is commonly visible at high latitudes (close to the north pole).
G2 (moderate) – frequency of 600 per cycle
- power systems: Power systems in high latitudes can experience voltage alarms and long-lasting storms can cause damage to transformers.
- Spacecraft operations: corrective actions in guidance may be necessary by ground control; possible changes in drag resistance affect orbit predictions.
- Other systems: High-frequency radio propagation can weaken at higher latitudes, and auroras have been seen as low as New York and Idaho (typically at 55° geomagnetic latitude).
G3 (strong) – frequency of 200 per cycle
- power systems: Voltage corrections may be necessary, false alarms may be triggered in some protection devices.
- Space operations: surface charge may occur on satellite components; drag may increase on low Earth orbit satellites and corrections may be needed for orientation problems.
- Other systems: Intermittent satellite navigation and low frequency radio navigation problems may occur; high-frequency radio can be intermittent, and auroras have been seen as low as Illinois and Oregon (typically 50° geomagnetic latitude).
G4 (severe) – frequency of 100 per cycle
- power systems: Possible widespread voltage control problems and some protection systems may erroneously disconnect the network.
- Spacecraft operations: Charging and tracking issues may occur on the surface, corrections may be needed for orientation issues.
- Other systems: induced currents in pipelines affect preventive measures; sporadic high-frequency radio propagation, satellite navigation degraded for hours, low-frequency radio navigation disrupted, and auroras were seen as far south as Alabama and northern California (typically at 45° geomagnetic latitude).
G5 (extreme) – frequency of 4 per cycle
- Power Systems: Widespread voltage control problems and protection system problems may occur, some grid systems may experience complete breakdown or blackouts. Transformers may be damaged.
- Spacecraft Operations: Extensive surface loading, problems with orientation, ascent/descent communication, and satellite tracking may occur.
- Other systems: currents in ducts can reach hundreds of amps, high-frequency radio propagation may be impossible in many areas for one to two days, satellite navigation may be degraded for days, low-frequency radio navigation may be out of range. air for hours, and auroras have been seen as far south as Florida and southern Texas (typically 40° geomagnetic latitude).
Source: United States Oceanic and Atmospheric Agency (NOAA)