On Friday (9), the Space Weather Prediction Center (SWPC) of the National Oceanic and Atmospheric Administration (NOAA) of the United States announced that the side of the Sun facing Earth has almost 300 spots (regions that can explode) – the highest number in more than 20 years.
The amount on the far side may be even greater. Helioseismic maps of the far side reveal vast areas of potential sunspot activity:
In the central part of the map (gray), the visible side of the Sun; on the sides, the hidden side. Credit: SWPC/NOAA
In the image above, the areas marked with arrows are spots so large that they affect the way the entire star vibrates. NASA’s Solar Dynamics Observatory (SDO) can measure the vibrations, allowing helioseismologists to identify clusters of distant active regions that are invisible from Earth.
The unofficial number of daily sunspots estimated by the SWPC on Thursday (8) was 337, a value not observed since March 2001. However, the official information is determined by the World Data Center Sunspot Index and Long-term Solar Observations (WDC-SILSO) and its Solar Influences Data Center (SIDC) at the Royal Observatory of Belgium, which indicated 299. On September 1, the final report with the definitive number will be presented.
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Most active regions on the Sun on August 9, 2024. Credit: Courtesy of NASA/SDO and the AIA, EVE, and HMI science teams, with labeling from the EarthSky platform.
Let’s understand:
The Sun’s magnetic fields are constantly active; When high concentrations of internal magnetic energy occur, dark spots appear on the star; These spots can explode as a result of the internal pressure of the magnetic fields becoming entangled; When this happens, the star shoots jets of plasma into space; These jets are also called coronal mass ejections (CME); If CMEs are launched towards Earth, they can reach the planet’s atmosphere and react with the magnetosphere; This causes geomagnetic storms; Depending on their power, these storms can cause everything from the formation of auroras to more serious effects, such as interruptions in communication systems or even the downing of satellites in orbit; Solar activity oscillates in cycles of about 11 years; We are currently in cycle 25 (that is, the 25th since scientists began observing this dynamic); Near the peak of each cycle (Solar Maximum), our star becomes more “angry”; This means that eruptions occur in greater numbers and are more violent; The Solar Maximum of the current cycle was predicted for next year, but everything indicates that, in addition to having arrived earlier, it will be even stronger than estimated by scientists in 2019.
How is solar maximum defined?
To determine when solar maximum occurs, researchers rely on long-term historical records of sunspot numbers, advanced statistics and models of the solar dynamo – the flow of hot, ionized gases within the star that generates the star’s magnetic field, which in turn drives the solar cycle.
Accurate predictions of solar activity are crucial, as geomagnetic storms triggered by CMEs can disrupt power grids and radio and GPS signals, knock satellites out of place and pose a radiation risk to airplane pilots and astronauts in Earth orbit.
Early warning of space weather events can help implement protective procedures to reduce risks.
