NASA’s Solar Dynamics Observatory captured this image of an X9.0 solar flare – as seen in the bright flash in the center – on Oct. 03, 2024. The current solar cycle has reached its maximum. Credit: NASA/SDO
Powerful geomagnetic solar storms mark new phase of 11-year cycle, as Parker Solar Probe comes ever closer to the Sun’s surface.
Solar Cycle 25—by far the most thoroughly observed solar cycle in history—has reached its maximum phase, NASA and the National Oceanic and Atmospheric Administration (NOAA) announced recently, weeks after a geomagnetic solar storm sparked a powerful coronal mass ejection that touched off sitings of the Aurora Borealis as far south as Florida and Mexico.
The current solar cycle began in December of 2019, from a quiet phase of solar activity known as the solar minimum, marked by diminished sunspots and solar flares, sometimes separated by days or weeks.
“Over the last five years, that activity has ramped up,” said Lisa Upton, co-chair of the Solar Cycle Prediction Panel and lead scientist at Southwest Research Institute in San Antonio, Texas, speaking at a recent NASA press conference. “What we are currently experiencing … indicates that the Sun has reached the maximum phase of the solar cycle. Even though we’re currently in the maximum phase, we will not be able to determine the peak of this solar cycle for several months because we need to track a consistent decline in solar activity first.”
Solar activity over a 9 year period. Credit: NASA/Goddard Space Flight Center
During solar maximum, the Sun can be speckled with hundreds of spots at once. These sunspots, which can be anywhere from 1,000 to 100,000 miles across, are marked by a concentration of intense magnetic field lines, tangled by the movement of the Sun’s plasma. Sunspots often point to active regions that expel solar flares and powerful coronal mass ejections.
“When the activity is directed towards Earth, a solar storm can create a major disturbance in the Earth’s magnetic field, called a geomagnetic storm…,” said Kelly Korreck, program scientist, NASA’s Heliophysics Division. “That can produce effects such as radio blackouts, power outages, and beautiful auroras.”
NASA’s Solar Dynamics Observatory captured this image of a solar flare – as seen in the bright flash on the right – on May 14, 2024. Credit: NASA/SDO
In large geomagnetic storms, the Sun can eject a billion tons of plasma, with a powerful magnetic field embedded within it, into space. When it arrives at Earth, it interacts with the magnetosphere, ionosphere, and thermosphere. In May of 2024, a series of large coronal mass ejections disrupted technology on Earth, including a $500 million impact to the agriculture industry, where high-precision GPS systems guide seed planting, tilling, and irrigation. The May event was the largest since October 2003.
“I think this was probably the most prepared we have been to successfully mitigate extreme space weather,” said Bill Murtagh, program coordinator, NOAA’s Space Weather Prediction Center. “If these preparedness actions were not in place, the storm could have been much more consequential, and more work needs to be done because we know we can get much bigger storms than have occurred so far this cycle. For example, September 1859, known as the Carrington event, the February 1872, the May 1921, all big storms, several times bigger than occurred in May of this year. That is our concern. Are we ready for a storm of that magnitude?”
Astronomers have been observing sunspots for more than 400 years. In 1844, an amateur astronomer named Heinrich Schwabe first identified that the presence of sunspots and the number of days between them increased and decreased in cycles of about a decade. Solar Cycle 25 is shaping up to be a relatively small cycle, although slightly larger than Cycle 24, which was the quietest in nearly 100 years.
As Parker Solar Probe passed through the corona on encounter nine, the spacecraft flew by structures called coronal streamers. These structures can be seen as bright features moving upward in the upper images and angled downward in the lower row. Such a view is only possible because the spacecraft flew above and below the streamers inside the corona. Until now, streamers have only been seen from afar. They are visible from Earth during total solar eclipses.
Credit: NASA/Johns Hopkins APL/Naval Research Laboratory
“We are anticipating another year or so of maximum phase before we really enter the declining phase, which will lead us back to solar minimum,” Upton said. “This period of solar decline is marked by a decreasing number of sunspots, but not necessarily by fewer impacts. Even after the solar maximum has passed, high impact space weather is possible, and in fact the declining phase is notable for often having very strong solar events.”
In addition to the usual solar cycle observations, scientists studying this cycle will have powerful new data sources to examine.
NASA’s Parker Solar Probe launched on August 12, 2018, and the spacecraft was travelling to the Sun when Solar Cycle 25 began. In December of 2021, it began an unprecedented examination of our solar system’s star by successfully flying through the Sun’s corona, sampling particles and magnetic fields. It was the first time a spacecraft had come so close to the Sun, and it has come much closer since.
On October 3, 2024, the same day the Sun emitted a powerful X9.0 solar flare, the Parker Solar Probe completed its 21st elliptical orbit through the corona, coming within 4.51 million miles of the surface and travelling 394,700 miles per hour. On December 24, the spacecraft will make the first of three final orbits in its primary mission, coming within 3.8 million miles of the Sun and accelerating to about 430,000 miles per hour.
The European Space Agency’s Solar Orbiter made its first approach to the Sun on June 15, 2020, getting as close as 47.8 million miles to the Sun’s surface. At certain points in the missions, researchers will be able to coordinate data between the two spacecraft to have multiple viewpoints of the Sun’s corona and the corresponding solar wind.
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