NASAA solar cycle refers to the cycle that the Sun’s magnetic field goes through approximately every 11 years. The sun is a made up of electrically charged hot gas. As the charged gas moves it creates a strong magnetic field. Roughly every 11 years the Sun’s magnetic field flips. The activity on the Sun varies over the cycle because the magnetic field causes the sunspots that can be seen on the Sun. One of the ways that the cycle is tracked is by counting the number of sunspots. The solar minimum is the beginning of a cycle and is marked by the Sun having the lowest number of sunspots. Then over time the solar activity and hence the number of sunspots increases. This is until it hits the solar maximum, which is the midpoint of a solar cycle. This is when the magnetic field flip occurs. Then the solar activity decreases until the solar minimum is reached and then a new cycle begins.
Evolution of the Sun in extreme ultraviolet light from 2010 to 2020, as seen from Europe’s PROBA2 spacecraft. [6]
Sunspots range from 1,000 to 1000, miles across and the occur where there is an intense concentration of magnetic field lines. These lines are driven by the movement of the Sun’s plasma. These temporary patches on the sun are slightly cooler than the material around them thus appearing darker. Sunspots typically indicate an active region that will expel solar flares and powerful coronal mass ejection.
Sunspots are not the only thing that changes as the sun progresses through a solar cycle. Eruptions on the sun increases during the solar cycle and come in the form of solar flares and coronal mass ejects. These send energy and material space. This is what causes the aurora that can be seen on Earth as the particles from coronal mass ejection interact with the gases in the Earth’s atmosphere. When the solar cycle reaches its maximum phase, these ejections become more frequent, with the more powerful ones allowing the aurora to be seen father down the Earth’s hemisphere. However giant flares and coronal mass ejection can occur at any point during the cycle, so it is important to stay prepared for these events.
When a solar storm occurs in the direction of the Earth it causes a geomagnetic storm, which is when the solar storm creates disturbances in the Earth’s magnetic field. The sun can eject a billion tons of plasma, which has a magnetic field embedded in it. When it gets to Earth it interacts with the magnetosphere, ionosphere and thermosphere. These storms can cause radio blackouts, disrupt electrical grids and impact navigations signals. They can also interfere with satellites that are in orbit and hence the services that they provide. It is one of the things that must be considered for space missions as they are a radiation hazard for astronauts in space. A series of large coronal mass ejection events in May 2024 had a $500 million impact on the agriculture industry. There are warning signs for these geomagnetic storms. These come in the form of sunspot groups coming up from under the solar surface and they leave a dark pattern from across the disks. Advanced warnings allow for satellites, power gris, and astronauts to take protective measures.
The current solar cycle, 25, began in the December of 2019. The current cycle follows an unusual solar cycle. Solar cycle 24 had the 4th lowest intensity since the solar cycles started to be recorded in 1755. It was the weakest in 100 years and had a below average maximum solar spots of 114, with the average being 179. This low number of sunspots was caused by the northern and southern hemisphere having staggard solar maximums. The northern hemisphere sunspots peaked 2 years before the southern hemisphere. The length of the cycle was average, with a length of 11 years.
It is predicted that Solar Cycle 25 will follow the small cycle, however it will be slightly bigger than Cycle 24. With its peak forecasted for this July 2025, and it should peak at 115 sunspots. These strength predictions are made based on the speed that the solar activity rises. The sunspots have been steadily increasing at a slow pace. It is solar cycle predictions like this that are important to aid in anticipating space weather storms.
The NOAA/NASA forecast for Solar Cycle 25. [6]
References
[1] Wilcox, K. (2024). Solar Cycle 25 Reaches Maximum | APPEL Knowledge Services. Nasa.gov. URL: https://appel.nasa.gov/2024/10/30/solar-cycle-25-reaches-maximum/
[2] US Department of Commerce. (2020) Hello Solar Cycle 25, www.weather.gov. URL: https://www.weather.gov/news/201509-solar-cycle
[3] NASA (2015) What Is the Solar Cycle? | NASA Space Place, Nasa.gov. URL: https://spaceplace.nasa.gov/solar-cycles/en/.
[4] ESA. (2020). Solar cycle 25: the Sun wakes up. URL: https://www.esa.int/Space_Safety/Solar_cycle_25_the_Sun_wakes_up
[5] NASA (2024). Light filtered image of the Sun allowing for sunspots to be seen, captured in August 2024 by NASA’s Solar Dynamics Observatory spacecraft. URL: https://static.scientificamerican.com/dam/m/1d7ac7f9943090c/original/Sunspots.jpg?m=1723747432.902&w=1000
[6] Dan Seaton/European Space Agency. Evolution of the Sun in extreme ultraviolet light from 2010 through 2020, as seen from Europe’s PROBA2 spacecraft. URL: https://spaceplace.nasa.gov/solar-cycles/en/solar-cycle_2010-2020.en.jpg
[7] NOAA.(2019) The NOAA/NASA forecast for Solar Cycle 25. URL: https://www.esa.int/var/esa/storage/images/esa_multimedia/images/2020/10/solar_cycle_25_prediction_noaa/22288525-2-eng-GB/Solar_cycle_25_prediction_NOAA_pillars.jpg
Leave a Reply
Want to join the discussion?Feel free to contribute!