The Sunspot Cycle is a natural phenomenon that occurs in our Sun. It leads to an increase in activity on the surface of the Sun and takes place over an average of 11 years. How does the Sunspot Cycle Directly Relevant To Us Here On Earth?
The frequency of sunspots and solar flares increases and decreases cyclically. Also, the magnetic poles of the Sun reverse periodically. The Sun has a great influence on our life on Earth. But how does the Sunspot cycle affect us?
The Sunspot Cycle can affect our electrical systems, radio communications, and produces auroras. Find out all about it in this article.
What Are Sunspots
Sunspots are small areas in the Sun’s photosphere that are slightly cooler than the surrounding gasses. They are usually a few tens of thousands of miles side (about the size of Earth, the Sun is very big). However, they may grow large enough to be visible without a telescope (using an appropriate filter). They are not permanent; individual spots typically last about four weeks.
Sunspots are the result of the distortion of the Sun’s magnetic field. Unlike the Earth, the Sun does not rotate as a rigid body. It is gaseous so the areas towards the equator rotates faster than at the poles. Because the Sun is composed of a plasma (i.e. ionized gas) the rotating material drags with it the magnetic field. Differential rotation distorts the magnet field and may become concentrated in certain spots. Sunspots are the result of the Sun’s magnetic field becoming locally concentrated.
The sunspot cycle is also commonly known as the solar cycle, solar magnetic activity cycle, and Schwabe cycle. You may see any of these terms used, but they all refer to the same thing.
The sunspot cycle is a natural activity that involves our Sun. The Sun is a huge ball of hydrogen and helium gas held together by gravity.
The gasses are electrically charged and constantly move around, generating a powerful magnetic field.
Solar Activity Changes
The sun’s magnetic field fluctuates and changes, affecting the amount of activity on the solar surface. Sunspots can appear, and the frequency and intensity of these sunspots build throughout the Sunspot Cycle.
At the beginning of the cycle, the Sun has its lowest number of sunspots. This is known as solar minimum. Over time, the number of sunspots increases until they reach their height.
A solar maximum occurs in the middle of the cycle when sunspots peak. Once the solar maximum has been reached, the sunspots begin to fade back down until they reach the solar minimum once more.
A Sunspot Cycle can last anything from 9 to 14 years. It averages around 11 years, the number most commonly used for the Sunspot Cycle.
The Magnetic Poles Flip
Earlier it was mentioned that sunspots operate on an 11-year cycle. This relates to sunspot activity. In reality, it is a 22-year cycle. So let’s continue the story to see why.
Due to differential rotation and convention in the Sun’s interior, twisting of the magnetic field progresses. After about 11 years the twisting results in the magnet field become relaxed due to cancellation of the field. The Sun’s magnetic field will become zero before re-establishing itself. However, due the the process of relaxing the field the polarity of the Sun is reversed: what was the magnetic north pole becomes the magnetic south pole and vice versa. The process then repeats to complete the 22-year cycle.
For more information on the Solar Cycle see The Solar Cycle.
Earth’s Poles Can Change Too
The change in the Sun’s polarity may sound strange, but it is a phenomenon that happens on Earth as well. Although it only takes about 11 years to occur on the Sun, it takes an average of 300,000 years for the Earth’s poles to reverse.
It’s thought that the Earth’s poles have reversed 183 times over the last 83 million years. The last reversal occurred around 780,000 years ago. Given that, on average these occur every 300,000 years a flip is overdue.
How Does The Sunspot Cycle Affect The Solar System?
This increase and decrease in solar activity and polarity reversal greatly affect the solar system. The solar winds produced by the Sun extend for billions of miles and reaches past even Pluto. Where the solar winds stopped is called the heliopause. The heliopause is the boundary between the solar system and interstellar space.
Planets like Earth feel less affected than others due to the protective magnetosphere surrounding the planet. However, planets that don’t have this protective layer can be greatly influenced by the change in polarity.
For example, Venus doesn’t have a protective magnetosphere. During the Sunspot Cycle in 2006, the sun ejected a mass of plasma and a magnetic field known as a coronal mass ejection (CME.)
This CME hit Venus and stripped oxygen from the planet’s atmosphere!
Mars once had a significant atmosphere. Its small size resulted in the interior of the planet cooling. With a cool solid interior, the planet lost its magnetosphere. The planet’s atmosphere was stripped away without protection from the solar wind. For the same reason, Mars’ water was also lost at the same time.
How Does The Sunspot Cycle Affect Earth?
We just learned that Earth escapes the most severe effects of the Sunspot Cycle, but that doesn’t mean that it does not affect Earth at all.
The Sun provides all of our natural light, heat, and energy. As such any fluctuations in its activity and behavior will surely influence us.
Electrical Systems
When CMEs occur, more charged particles enter the Earth’s atmosphere. This can affect the performance of electrical systems such as power grids by inducing additional currents.
In some circumstances, it can lead to large blackouts across regions of the Earth.
Thankfully, many countries now have measures in place to combat this. Although CMEs have caused blackouts, they’re less likely to occur.
Radio Blackouts
An increase in electromagnetic energy often causes radio blackouts. They are most likely to be caused by a solar flare. The electromagnetic energy in the solar flares can disrupt the Earth’s upper atmosphere.
Unfortunately, this is the area where communication signals usually travel, and it can lead to blackouts.
CMEs can reach the Earth in 15 – 18 hours, so the effects of a solar flare can be quickly felt. However, slower-moving ones can take as long as four to five days. Once the solar flare is identified radio frequencies can be changed to work around any disruption.
Currently, our primary method of detecting CMEs is the Large Angle and Spectrometric Coronagraph (LASCO) instrument onboard the Solar and Heliospheric Observatory (SOHO). The spacecraft orbits a point between the Earth and Sun. For more information see Coronal Mass Ejections and Solar and Heliospheric Observatory.
Auroras
Both the Aurora Borealis and Aurora Australis are created by solar activity. Increased solar activity generates more electrically charged material, leading to more frequent and spectacular aurora.
The color of the auroras results from charged particles interacting with gasses in our atmosphere. The charged particles cause electrons in gas particles to move to higher energy levels. When the electrons return to their ground state light is emitted in distinctive wavelengths (i.e. colors). Red hues are produced by interaction with nitrogen molecules, and green by interactions with oxygen molecules.
Space Exploration And Satellites
Radiation storms caused by increased solar activity can cause problems with aspects of space exploration and satellite systems. If increased radiation is observed, satellite systems may be powered off so they aren’t damaged.
It can also endanger any astronauts that are in orbit during the time of the radiation storm. Astronauts may need to build additional shelter in their spacecraft or move to areas that are better protected.
Final Thoughts
In this article, we learned what the Sunspot Cycle is and how it can affect life on Earth.
If you wish to read a more in depth article about the effect of sunspots and other solar activity you can see Space Weather.
Hi, my name is Jason Anderson, and I am a Physics Professor. Ever since I was a kid, I’ve been fascinated with space, the universe, the moon, you name it. I spent hours and hours at the planetarium close to my hometown, wondering what else could be out in the universe.
Since then, I’ve been an avid stargazer and astronomer, and love nothing more than spending my time charting stars, observing planets, and finding constellations.
This is why I decided to start Telescope Guru. I only wish to share this fun pastime with the world. With this site, I hope to answer all of your questions relating to astronomy, telescopes, and stargazing.
