Archiv: solar cycle 23


05.07.2026 - 10:42 [ Monthly Notices of the Royal Astronomical Society ]

Subsurface structural changes associated with successive 11-yr solar activity cycles have been progressively more confined near the surface: new helioseismic results on Cycles 22–25 from BiSON

(May 28, 2026)

We use Sun-as-a-star helioseismology data, collected by the Birmingham Solar-Oscillations Network, to examine the relationship between the solar-cycle-induced frequency shifts of whole-Sun, low-angular degree solar p modes and well-known proxies of global solar activity. Changes in behaviour between the low-frequency modes and proxies, which in a previous study we found had occurred on the declining phase of Cycle 23, appear to have persisted into Cycle 25. More striking is a significant change in the relationship for higher-frequency modes, which the new Cycle 25 data now reveal. The observed mean frequency shifts in Cycle 25 are much stronger than one would expect for these modes based on the relationship between the frequencies and proxies seen in previous cycles, in particular Cycle 22. In sum, Cycle 25 is as strong as Cycles 22 and 23 when observed in this higher-frequency seismic band, in marked contrast to the relative sizes of the cycles seen in the global activity proxies, where Cycle 25 is noticeably weaker. (…)

The last few solar cycles have seen significant changes in overall levels of activity and differences in the evolution of magnetic fields at different solar latitudes (e.g. see D. H. Hathaway 2015; A. Norton et al. 2023). Cycle 24 was significantly weaker in well-known proxies of global solar activity than previous cycles, and marked a departure from the preceding so-called modern maximum epoch (I. G. Usoskin 2017). While the current Cycle 25 has peaked at higher activity, it did not return to pre-Cycle-24 levels.

05.07.2026 - 10:31 [ University of Birmingham ]

Listening to the Sun reveals previously hidden changes to solar cycle

(May 28, 2026)

Professor Sarbani Basu, from Yale University, said, “We discovered that the relationship between internal solar oscillations and surface activity has evolved over the past few cycles. This trend cannot be explained simply by weaker magnetic fields. Instead, it indicates a structural reorganisation of how the Sun’s magnetic activity is stored beneath the surface.”

Ongoing collection and analysis of BiSON solar data over what remains of Cycle 25 and into the upcoming Cycle 26 will be crucial in determining whether the changes discovered in the Sun’s activity point to a sustained, systematic change in solar magnetic behaviour.

05.07.2026 - 10:28 [ UniverseToday.com ]

The Sun is Changing and We Don’t Know Why

(May 29, 2026)

Here‘s where it gets strange. Traditional measurements of solar activity such as sunspot counts and magnetic field strengths at the surface suggest that cycle 25 is relatively modest. But the helioseismic data tells a different story. Look at the high-frequency oscillations, which probe the shallowest layers, and cycle 25 appears just as powerful as its predecessors. The Sun looks different depending on where you look. The surface is playing it down but the interior is not.

What does this mean? The honest answer is that nobody is entirely sure yet.

24.04.2023 - 11:25 [ Times of India ]

Study: Sun’s magnetic field is weakening

(Oct 7, 2019)

The research, according to the team, will help monitor and evaluate the influence of solar activities and their implications on the Earth’s climate. The astrophysicists’ team included experts from Ahmedabad’s Physical Research Laboratory (PRL), Japan, and China.

25.10.2021 - 18:30 [ Electroverse.net ]

Solar Cycle 25 Progressing Similarly to 24, + Fairbanks sees Record-Breaking Snowfall

(October 6, 2021)

The official forecast by the NOAA/NASA Solar Cycle 25 Prediction Panel (made in 2019, and visualized by the red line above) called for a weak cycle 25, peaking in July 2025. And while things are currently tracking slightly ahead of schedule, NOAA don’t believe that the cycle will peak any higher than SC24. Instead, they simply see the peak arriving earlier, in late-2024 (rather than mid-2025). If this plays out it would of course mean an earlier start to Solar Cycle 26, too …

25.10.2021 - 18:04 [ Times of India ]

Study: Sun’s magnetic field is weakening

(Oct 7, 2019)

The research, according to the team, will help monitor and evaluate the influence of solar activities and their implications on the Earth’s climate. The astrophysicists’ team included experts from Ahmedabad’s Physical Research Laboratory (PRL), Japan, and China.

11.08.2019 - 13:45 [ National Aeronautics and Space Administration ]

Long Range Solar Forecast: Solar Cycle 25 peaking around 2022 could be one of the weakest in centuries.

(10.05.2006)

How do you observe a belt that plunges 200,000 km below the surface of the sun?

„We do it using sunspots,“ Hathaway explains. Sunspots are magnetic knots that bubble up from the base of the conveyor belt, eventually popping through the surface of the sun. Astronomers have long known that sunspots have a tendency to drift—from mid solar latitudes toward the sun‘s equator. According to current thinking, this drift is caused by the motion of the conveyor belt. „By measuring the drift of sunspot groups,“ says Hathaway, „we indirectly measure the speed of the belt.“

13.07.2019 - 16:40 [ EOS.org ]

The Thermosphere Responds to a Weaker Than Normal Solar Cycle

The cooling near solar minimum is natural and specific to the thermosphere. The cooling thermosphere does not affect the troposphere, the layer of the atmosphere closest to Earth’s surface where people live. The temperatures we experience on the ground do not get colder because of this solar cycle. NASA and other climate researchers continue to see a warming trend in the troposphere. These two effects are ongoing but unrelated.

Nitric oxide and carbon dioxide play important roles in cooling the thermosphere.

29.04.2019 - 13:15 [ Stanford University ]

ON THE WEAKENING OF THE POLAR MAGNETIC FIELDS DURING SOLAR CYCLE 23

(20. Dezember 2009)

The Sun’s polar fields are currently ∌40% weaker than they were during the previous three sunspot minima. This weakening has been accompanied by a corresponding decrease in the interplanetary magnetic field (IMF) strength, by a ∌20% shrinkage in the polar coronal-hole areas, and by a reduction in the solar-wind mass flux over the poles. It has also been reflected in coronal streamer structure and the heliospheric current sheet, which only showed the expected flattening into the equatorial plane after sunspot numbers fell to unusually low values in mid-2008. From latitude–time plots of the photospheric field, it has long been apparent that the polar fields are formed through the transport of trailing-polarity flux from the sunspot latitudes to the poles.