A solar cycle breakthrough can help protect spacecraft from huge energy bursts
A collaborative research effort from scientists in Belgium, Austria, Croatia, and Russia has developed a new method to determine the strength of the solar cycle, an institutional press release said.
In the 17th century, Galileo Galilei turned his telescope toward the Sun to find sunspots there. Over centuries, astronomers have seen the sunspots appear and disappear and even found a correlation between their frequency and a longer period of time i.e. 11 years, called the solar cycle.
According to NASA's webpage, as the electrically charged gases move inside the Sun, they generate a magnetic field that flips every 11 years. This means that the North Pole on the Sun turns south and vice versa every 11 years, after which it takes another 11 years for it to become the North Pole again.
Effects of the Solar Cycle
The change in the magnetic field on the Sun also brings out powerful magnetic fields from the Sun's interiors, observed as darker spots on the solar surface or sunspots. What Galileo and scores of astronomers saw over the years were magnetic tubes that were carrying solar matter from one sunspot, completing a giant loop, and entering the Sun from another sunspot.
Like magnets, sunspots also exist in pairs or opposite polarities, and free magnetic energy accumulated in these loops can suddenly be released in the form of a flare or coronal mass ejection (CME). In a matter of seconds, a solar flare can release energy that is 100,000 times more than the energy all power plants across the world generate every year, the press release added.
Such high amounts of energy could devastate species, but the Earth is protected by its atmosphere, which shields us from the harmful effects of the flares. Unluckily, spacecraft sent by humans are not immune from these powerful outbursts of energy, like the 40 Starlink satellites that were deorbited by SpaceX after a solar flare disrupted their mission. For a brief moment, communications lost due to a solar flare meant that airplanes disappeared over the radars in Sweden in 2015.
Measuring the Solar Cycle
To be in a position to better predict when solar flares might cause disruptions, as many as 80 observatories are now observing the Sun from all over the world. With the Sun currently in an active phase of its solar cycle, we need to be more vigilant about such incidents that can cause radio blackouts or even crash electrical grids. Yet, we have incidents where geomagnetic storms hit the Earth without anybody managing to spot them in advance.
So, a multinational collaboration of researchers has come up with a new method to predict the strength of the solar cycle itself. The team showed that the maximal growth rate of sunspot activity during the ascending phase of a solar cycle is a reliable predictor of the amplitude of the solar cycle. Using a catalog of sunspot numbers, the researchers showed that predictions of the amplitudes are more accurate when solar activity is considered separately for the two hemispheres of the Sun.
"We have learned from our study that we can obtain more accurate predictions of solar activity when using hemispheric sunspot data, which capture the asymmetric and out-of-phase behavior of the solar magnetic field evolution in the north and the south solar hemispheres," said Astrid Veronig, professor at the University of Graz, who was involved in the study.
"Our method can be used in real-time, we can predict the cycle amplitude continuously over the development of the ascending phase of a solar cycle and update the prediction when the latest value of the growth rate is larger than the previous one," said Olga Sutyrina, a graduate student at Skoltech who was also involved in the research. "With currently available data, we predict that the lower estimate of the amplitude of the current solar cycle (no. 25) will be 110±26, which is comparable with the previous 11-year solar cycle (no. 24)."
The researchers published their findings in the journal Astronomy and Astrophysics.