Solar activity is reflected through the Sun’s cycle, which has a periodicity of 11 years, and it can also be called the Solar magnetic activity cycle, Sunspot cycle, or Schwabe cycle. The cycle has an active 7-year period during which solar flare events are probable and a quiescent 4-year period during which solar flare events are rare.   

Nowadays, several instruments monitor solar activity. The National Environmental Satellite, Data, and Information Service (NESDIS) monitors the Sun’s conditions and the space environment around the Earth, using measurements collected by instruments on satellites. “Space weather” generally refers to conditions resulting from solar activity and space storms that can potentially affect Earth, our atmosphere, and the near-Earth space environment. Currently, we also have two missions of satellites orbiting the sun closer than ever before, ESA’s and NASA’s Solar Orbiter, and NASA’s Parker Solar Probe, with the purpose of gathering data about the origin of many of the processes that happen during the solar cycle. 

The National Oceanic and Atmospheric Administration’s (NOAA) Space Weather Prediction Center, in Washington, is another example that analyzes sunspots daily, to assess which ones are the most threatening to us. Analyzing the size and position of sunspots allows them to predict when a solar flare will occur and how intense it will be. 

Solar activity refers to various phenomena occurring in the Sun, primarily driven by its magnetic field, and we are going to describe a few of these phenomena, below: 

• Sunspots: Dark and cooler areas on the Sun’s surface caused by concentrations of magnetic field flux that inhibit convection. They are associated with intense magnetic activity and typically come ahead of solar flares and Coronal Mass Ejections (CMEs). 

• Solar Flares: Intense bursts of radiation caused by the release of magnetic energy in the solar atmosphere. They are so intense that can affect communication systems, power grids, and satellites on and around Earth.  

• CMEs: Large expulsions of plasma and magnetic field from the Sun’s corona. The stellar corona is the outermost layer of a star’s atmosphere and is composed of plasma. CMEs can also cause geomagnetic storms, responsible for disturbing satellites, communication systems, and power grids.  

• Solar Wind: A stream of charged particles released from the corona that interact with the Earth’s magnetic field and atmosphere. The variations from the solar wind can also cause auroras on Earth.   

Understanding and forecasting solar activity is important to prepare us for the effects of space weather on technology and infrastructure on Earth.