Tag: solar cycle

New data: the ozone hole occurs mostly because of the sunspot cycle and cosmic rays, not CFC pollution

July 2, 2025 1:18 pm Robert Zimmerman

The ozone hole linked to the solar cycle

The uncertainty of science: A science paper released yesterday suggests that the ozone hole over Antarctica that scientists have been tracking for almost a half century is caused mostly by the solar cycle and the accompanying fluctuations in cosmic rays hitting the upper atmosphere, not the release of chlorofluorocarbons (CFCs) that used to be used in aerosol spray cans.

The graph to the right, from figure 2 of the paper, illustrates the data. The red line is the ozone hole fluctuations predicted by the paper’s model, labeled “CRE Theory”, based on the increase of cosmic ray radiation during solar minimum. The blue, black, and green lines indicate the actual fluctuations of ozone and temperature in the lower stratosphere where the ozone layer exists. As you can see, the model and actual fluctuations match quite closely. From the paper’s abstract:
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Sunspot update: Sunspot activity rebounds somewhat in June

July 2, 2025 12:13 pm Robert Zimmerman

As I have done since I started this website fifteen years ago, I post at the start of every month an update of the Sun’s ongoing sunspot activity, using the update that NOAA posts each month to its own graph of sunspot activity but annotated by me with extra information to illustrate the larger scientific context.

Below is that graph, showing that in June sunspot activity rebounded upward somewhat from the shocking drop in activity that occurred in May.

Sunspot update: The Sun confounds the predictions again!

June 3, 2025 11:27 am Robert Zimmerman

It is time for my monthly update of the Sun’s ongoing sunspot activity, using the update that NOAA posts each month to its own graph of sunspot activity but annotated by me with extra information to illustrate the larger scientific context.

The activity in May was shocking in that it completely contradicted all expectations by everyone in the solar science community, with the Sun’s sunspot count changing in a way that was somewhat unprecedented. The graph below makes this very clear:

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Sunspot update: Activity rises slightly in April

May 6, 2025 1:06 pm Robert Zimmerman

It is the start of the month, so it is of course time for my monthly report on sunspot activity, based on the update that NOAA posts each month to its own graph of sunspots activity. As I have done since the start of Behind the Black in 2010, I take that graph each month and annotate it with extra information to illustrate the larger scientific context.

Sunspot activity in April did nothing to tell us anything about the Sun’s future activity. It rose slightly, but not by enough to suggest that the prediction put forth last month by NOAA scientists that the ramp down to solar minimum has begun is wrong.
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Sunspot update: Sunspot activity remains high but stable

March 3, 2025 3:02 pm Robert Zimmerman

The uncertainty of science Time for my monthly update on our Sun’s sunspot cycle, based on NOAA’s monthly graph of the sunspot activity on the Earth-facing hemisphere of the Sun, but annotated by me with additional information.

The graph below shows that the number of sunspots in February continued the trend during this solar maximum of being significantly higher than the consensus prediction by a panel of NOAA solar scientists, as indicated by the red curve. At the same time, the count in February was well below the high point during the summer of 2024. Instead, though it went up slightly in February it remains at about the same level we have seen since September.
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Sunspot update: Sunspot activity continued its decline in January

February 5, 2025 11:58 am Robert Zimmerman

Another month has passed, meaning it is time for another update on the Sun’s sunspot cycle, based on NOAA’s monthly graph tracking that activity but annotated by me with additional information.

In January the decline in sunspot activity on the hemisphere facing Earth since August 2024 continued, with the number of sunspots dropping to a level not seen since May 2023, when the Sun’s was ramping up from solar minimum to solar maximum.
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Sunspot update: Is this sunspot maximum over, or will it become another doubled peaked maximum?

January 2, 2025 12:43 pm Robert Zimmerman

Well, after almost fifteen years it had to happen at last. In preparing to do my monthly sunspot update today, which I had done every month since I started Behind the Black in 2010, I discovered that I had completely forgotten to do the update in December. Sorry about that.

No matter, the changes from month-to-month are not often significant, and fortunately that turned out to be the case in November and December of 2024. Since my last update at the beginning of November 2024, sunspot activity on the Earth-facing hemisphere of the Sun has been relatively stable, based on NOAA’s monthly graph tracking that activity. In November the activity dropped slightly, only to recover a small amount in December.
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Sunspot update: in October solar activity increased after September’s crash

November 4, 2024 3:35 pm Robert Zimmerman

Time for this month’s sunspot update. As I have done every month since I started this website in 2010, I am posting NOAA’s most recent update of its monthly graph tracking the number of sunspots on the Sun’s Earth-facing hemisphere, adding some additional details to provide context.

In October, following a crash in activity in September, the Sun showed a slight increase the number of sunspots. The increase did not match the drop from the month before, but it brought the activity back up to the level seen during the summer.
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NOAA and NASA declare the Sun has reached solar maximum

October 16, 2024 10:36 am Robert Zimmerman

Click for originial graph.

The uncertainty of science: During a press conference yesterday NOAA and NASA scientists announced that they now believe the Sun has reached solar maximum as part of its regular 11-year sunspot cycle.

“This announcement doesn’t mean that this is the peak of solar activity we’ll see this solar cycle,” said Elsayed Talaat, director of space weather operations at NOAA. “While the Sun has reached the solar maximum period, the month that solar activity peaks on the Sun will not be identified for months or years.”

Scientists will not be able to determine the exact peak of this solar maximum period for many months because it’s only identifiable after they’ve tracked a consistent decline in solar activity after that peak. However, scientists have identified that the last two years on the Sun have been part of this active phase of the solar cycle, due to the consistently high number of sunspots during this period. Scientists anticipate that the maximum phase will last another year or so before the Sun enters the declining phase, which leads back to solar minimum. Since 1989, the Solar Cycle Prediction Panel — an international panel of experts sponsored by NASA and NOAA — has worked together to make their prediction for the next solar cycle.

In other words, they have no idea yet it the actual peak has been reached. All they are really telling us is that the Sun is now in that maximum phase, something that has been very evident for many months.

This announcement is filled with a lot of blarney. For example, one scientist is quoted as saying the activity this maximum “has slightly exceeded expectations.” A simply glance at the graph they released, shown on the right, illustrates how wrong that statement is. The activity has been almost twice what was predicted (as indicated by the red curve). And though they say we have hit maximum, they admit they don’t know if we have reached the peak yet.

Having followed the predictions of the solar scientist community on this subject now for more than two decades, I have learned that this community knows far less than it lets on, and likes to exaggerate its capabilities to predict what the Sun will do. At the same time, they have also often played Chicken Little, warning everyone that if we don’t pay attention to them and do what they say, sun storms and solar activity will kill us all. (Interestingly, this announcement backs off somewhat from that doom-saying, making it a refreshing change.)

Sunspot update: Sunspot activity crashes in September

October 2, 2024 3:56 pm Robert Zimmerman

As it is the start of the month, it is time another monthly sunspot update, in which I provide some context and analysis to NOAA’s most recent update of its monthly graph tracking the number of sunspots on the Sun’s Earth-facing hemisphere.

After several months in which the number of sunspots rose considerably each month, in September the sunspot count crashed, dropping precipitously to levels closer to the various predictions of solar scientists, but still far above what they had all expected at this time of the solar maximum.

Sunspot update: The Sun continues to boom!

September 2, 2024 12:02 pm Robert Zimmerman

It is time for my monthly sunspot update, taking NOAA’s most recent update of its monthly graph tracking the number of sunspots on the Sun’s Earth-facing hemisphere and adding my own analysis as well as some additional details to provide the larger context.

During August the Sun continued to confound the experts, with the number of sunspots not only greater than July’s high count. the August count exceeded the numbers from December 2001 (215.5 vs 213.4), the last time the Sun was this active.

None of the predictions by anyone in the solar science community had predicted this level of activity.
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Sunspot update: In July the Sun produced the most sunspots in almost a quarter century

August 5, 2024 9:13 am Robert Zimmerman

Every month since this website began fourteen years ago, when NOAA posts its update of its monthly graph tracking the number of sunspots on the Sun’s Earth-facing hemisphere, I post my own analysis, adding some details to provide the larger context.

Of all those updates — numbering about 168 — this month’s is possibly the most significant. Since around 2008, the Sun began a long period where it was unusually quiet, with the solar maximum that occurred in 2014 possibly the weakest in two hundred years. Before that weak maximum begun, half the solar science community predicted it would be a very powerful maximum, while half predicted a weak maximum. Both got it wrong, though the weak prediction was closer though still too high.

When it came time to predict the next solar maximum, expected around 2025, that same solar science community was once again in disagreement. Most approved a NOAA science panel prediction in April 2020 calling for another weak minimum, similar to the one in 2014. A few dissented, however, and instead predicted in June 2020 that the maximum would be one of the strongest ever. In April 2023 however those dissenters chickened out, and revised their prediction downward, still forecasting a peak higher than the NOAA prediction but no longer anywhere as intense.

Based on what happened on the Sun in July, they should have had more faith in their earlier prediction.
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Do Kepler’s sunspot drawings tell us the length of the solar cycle in the 17th century?

July 26, 2024 9:19 am Robert Zimmerman

Kepler's first sunspot drawing
Click for original image.

The uncertainty of science: Scientists have done a new analysis of Johannes Kepler’s three drawings of sunspots on the Sun in 1607, and have concluded that the solar cycle at that time — just before the start of the Maunder grand minimum of no sunspots for decades — was about the same length, 11 years, that has been measured since the 1700s onward.

You can read the peer-reviewed paper here. The drawing to the right is figure 1 in that paper, and shows Kepler’s first drawing of the Sun’s surface showing sunspots. From the paper’s conclusion:

In combination with sunspot drawings in the 1610s–1620s, it is reasonable to suppose that the duration of the Solar Cycle −13 was between 11 and 14 yr. This does not support Miyahara et al.’s claim of anomalously long/short durations for Solar Cycle −13 (16 yr) and Solar Cycle −14 (5 yr) but supports Usoskin et al.’s reconstruction of regular durations of Solar Cycle −13 (11 yr) and Solar Cycle −14 (14 yr).

In other words, the solar cycle prior to the sixty-plus yearlong Maunder Minimum, when few to none sunpots occurred, was about eleven years long, like now, and not five years or sixteen years long, as some scientists have theorized. Knowing the length and nature of the cycle before the Maunder grand minimum would help scientists predict when the next minimum might occur. It would also help them better document the Sun’s long term behavior.

There is however great uncertainty in this result, since there really is so little data about sunspots prior to the Maunder Minimum. Before Galileo’s first use of the telescope in astronomy in 1609, such observations like Kepler’s were rare and very difficult. The conclusions here are intriguing, but hardly convincing.

In fact, it is really impossible to get a defiinitive answer from this data. We really won’t know how the Sun behaves just prior to a grand minimum until it happens again and scientists can use modern technology to observe it.

Sunspot update: The Sun keeps its boom going

July 1, 2024 4:45 pm Robert Zimmerman

Time for my monthly analysis of NOAA’s monthly tracking of the number of sunspots on the Sun’s Earth-facing hemisphere. As always, I have posted NOAA’s updated graph below, adding some details to provide the larger context.

In June the Sun continued the high activity from May, with the sunspot count significantly higher than predicted, 164.2 compared to the prediction of 104.9.
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Sunspot update: In May the Sun went boom!

June 3, 2024 12:43 pm Robert Zimmerman

As I have done at the start of every month since I begun this webpage back in 2010, I am posting NOAA’smonthly update of its graph tracking the number of sunspots on the Sun’s Earth-facing hemisphere, adding to it several additional details to provide some larger context.

While April had showed only a small uptick in sunspot activity, in May the sunspot activity on the Sun went boom, setting a new high for sunspots during this solar maximum as well as the highest sunspot count since September 2002. The sunspot count of 171.7 smashed the previous high of 160 this cycle, set in June 2023. This new high underlined was by the large solar flare on May 9th that sent the most powerful geomagnetic storm to hit the Earth’s magnetic field in many decades, producing spectacular auroras in many low latitudes.
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Solar storms are simply no longer a threat

May 20, 2024 3:39 pm Robert Zimmerman

The sunspot cycle as of May 2024. Click
for full details.

Today’s Chicken Little Report: When NOAA predicted on May 9, 2024 that a powerful solar flare had erupted from the Sun and was aiming a major solar storm directly at the Earth, the scientists at the federal government’s Space Weather Prediction Center could not help underlining the disaster potential, and were ably aided by the mainstream press. This CNN report was typical:

“Geomagnetic storms can impact infrastructure in near-Earth orbit and on Earth’s surface, potentially disrupting communications, the electric power grid, navigation, radio and satellite operations,” according to the Space Weather Prediction Center. “(The center) has notified the operators of these systems so they can take protective action.”

The center has notified operators in these areas to take action to mitigate the potential for any impacts, which include the possibility of increased and more frequent voltage control problems. Other aspects operators will monitor include a chance of anomalies or impacts to satellite operations and frequent or longer periods of GPS degradation.

And as always, the news report has to end with this warning of doom:
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Sunspot update: A minor uptick in sunspot activity in April

May 2, 2024 12:28 pm Robert Zimmerman

It is that time of the month again. Yesterday NOAA posted its monthly update of its graph tracking the number of sunspots on the Sun’s Earth-facing hemisphere. As I have done now for every month since I began this website in 2010, I have posted this updated graph below, with several additional details to provide some larger context.

In April the number of sunspots on the Sun went up somewhat, the count rising to the highest level since the count hit its peak of activity last summer. The sunspot number in April, 136.5, was however still significantly less than the 2023 peak of 160. Thus it appears the Sun is likely still the middle saddle of a doubled-peaked relatively weak solar maximum, with the Sun doing what I predicted in February 2024:
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Sunspot update: The weak solar maximum continues

April 2, 2024 10:38 am Robert Zimmerman

NOAA yesterday posted its updated monthly graph tracking the number of sunspots on the Sun’s Earth-facing hemisphere. As I do every month, I have posted this graph below, with several additional details to provide some larger context.

The sunspot activity in March dropped, continuing the pattern of the last five months, where the Sun appears to be in a stable plateau after reaching a high peak in the summer of 2023. It continues to appear that we are in the middle low saddle of a double-peaked relatively weak solar maximum, with the Sun doing what I predicted in February:

If we are now in maximum, sunspot activity throughout the rest of 2024 should fluctuate at the level it is right now, with it suddenly rising again near the end of the year for a period lasting through the first half of 2025. After that it should begin its ramp down to solar minimum.

Sunspot update: The Sun continues what appears will be a weak maximum

March 12, 2024 10:30 am Robert Zimmerman

As I have done each month since 2011, I am now posting an annotated version of NOAA’s monthly graph, tracking the solar sunspot activity on the Earth-facing hemisphere of the Sun. The NOAA updated graph was posted at the start of March, covering activity through the end of February, so this report is a little later than normal.

That graph is below. In February sunspot activity remained essentially steady, only slightly higher than the activity from the month before. Those numbers also hovered at about the same level seen since August 2023.
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Sunspot update: The Sun in January acted like solar maximum is here

February 2, 2024 11:11 am Robert Zimmerman

In my monthly sunspot update at the start of January, I asked in the headline “Are we now in the next solar maximum?”

The Sun’s sunspot activity in January since then has apparently answered that question. NOAA this week posted its monthly update of its graph showing solar sunspot activity on the Sun’s Earth-facing hemisphere, and as I do every month since 2011, I have posted that graph below, with annotations to provide a larger context.
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Sunspot update: Are we now in the next solar maximum?

January 3, 2024 9:57 am Robert Zimmerman

Time for my monthly update on the Sun’s sunspot activity has it proceeds through its eleven-year sunspot cycle. NOAA has released its update of its monthly graph showing the number of sunspots on the Sun’s Earth-facing hemisphere, and I have posted it below, annotated with further details to provide a larger context.

In December sunspot activity increased slightly for the second month in a row, but only by a little bit. The number of sunspots for the month was still significantly below the highs seen in the summer, and continue to suggest that the Sun has already entered solar maximum (two years early), and like the previous two solar maximums in 2001 and 2013, will be double peaked.
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Sunspot update: The Sun continues to prove that solar scientists understand nothing

December 1, 2023 3:49 pm Robert Zimmerman

With today’s monthly update from NOAA of its graph tracking the number of sunspots on the Sun’s Earth-facing hemisphere, we find that the Sun continues to confound the experts. As I do every month, I have posted this graph below, with additional details to provide the larger context.

In November the sunspot count rose slightly, but remained well below the highs that had occurred through most of the first half of 2023. Yet, despite that continuing reduction in the number of sunspots, the overall amount of activity remains above the prediction of some scientists, and below the prediction of other scientists.
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Sunspot update: October activity drops almost to predicted levels

November 1, 2023 3:55 pm Robert Zimmerman

NOAA today posted its updated monthly graph tracking the number of sunspots on the Sun’s Earth-facing hemisphere. As I do every month, I have posted this graph below, with several additional details to provide some larger context.

In October the sunspot count dropped so much from the activity in September that the total count was for the first time since the middle of 2021 actually very close to the predicted numbers first put forth by NOAA’s solar science panel in April 2020.

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Scientists: The solar cycle was only 8 years long during the Maunder Minimum in the 1600s

October 24, 2023 9:58 am Robert Zimmerman

Using archival records gathered in Korea during the 1600s when the Sun was undergoing a long period of almost no sunspots — called the Maunder Minimum — scientists have discovered evidence that the solar cycle during that time was only 8 years long.

You can read their paper here. Since almost no sunspots were visible at that time, the scientists used reports of aurora in Korea to determine periods when the Sun was more active. From their abstract:

By analyzing the variations in solar activity-related equatorial auroras recorded in Korean historical books in the vicinity of a low-intensity paleo-West Pacific geomagnetic anomaly, we find clear evidence of an 8-year solar cycle rather than the normal 11-year cycle during the Maunder Minimum.

This 8-year cycle is shorter than the 9-year cycle that other researchers had estimated based on the few sunspots that did appear during this grand minimum. Both conclusions however challenge what is known of the Sun. Since the 11-year cycle resumed in the 1700s, short cycles have generally been associated with very active periods, the opposite of what has been found during Maunder.

In other words, we know better what happened, but have no understanding of why. Since the Maunder Minimum appears associated with the Little Ice Age of the 1600s, and fits other data that says the climate cools when the Sun produces few sunspots, gaining some understanding of this process is important for understanding past and future changes to the global climate.

Sunspot update: Activity rises in September but not significantly

October 3, 2023 11:15 am Robert Zimmerman

Another month has passed, and it is once again time to post my annotated graph of NOAA’s monthly update of its graph that tracks the number of sunspots on the Sun’s Earth-facing hemisphere. The new graph is posted below, with several additional details to provide some larger context.

Last month we saw a drastic drop in August of sunspot activity, suggesting that the next maximum might possibly have been reached, though many months earlier than predicted. This month’s graph below, which shows an increase in activity in September but still well below the highs seen in June and July, strengthens that conclusion.
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The sunspot count in August demonstrates fully the utter uncertainty of science

September 2, 2023 1:46 pm Robert Zimmerman

In doing these sunspot updates every month since I started Behind the Black thirteen years ago, one of the repeated common themes has been noting how little we really know about the basic fundamental processes within the Sun. We know the process involves nuclear fusion combined with fission, and that process also creates a powerful magnetic field that every eleven years flips in its polarity. We also know that this eleven year cycle corresponds to an eleven year cycle of rising and then falling sunspot activity.

The devil however is in the details, and we know very little about those details. How those larger processes link to the specific changing features on the Sun remains little understood, if at all. The sudden and entirely unexpected steep drop in sunspot activity in August, as noted in the release yesterday of NOAA’s monthly update of its graph that tracks the number of sunspots on the Sun’s Earth-facing hemisphere, demonstrates this level of ignorance quite starkly.
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Scientists: Neptune’s clouds appear to ebb and grow in conjunction with sunspot cycle

August 17, 2023 9:24 am Robert Zimmerman

Graph showing correlation between Neptune's clouds and the sunspot cycle

Scientists have now discovered what appears to be a link between the coming and going of clouds on Neptune to the Sun’s 11-year-long sunspot cycle, despite Neptune receiving only 1/900th the sunlight of the Earth.

To monitor the evolution of Neptune’s appearance, Chavez and her team analyzed images taken from 1994 to 2022 using Keck Observatory’s second generation Near-Infrared Camera (NIRC2) paired with its adaptive optics system (since 2002), as well as observations from Lick Observatory (2018-2019) and the Hubble Space Telescope (since 1994). In recent years the Keck Observatory observations have been complemented by images taken as part of Keck Observatory’s Twilight Observing Program and by Hubble Space Telescope images taken as part of the Outer Planet Atmospheres Legacy (OPAL) program.

The data revealed an intriguing pattern between changes in Neptune’s cloud cover and the solar cycle – the period when the Sun’s magnetic field flips every 11 years, causing levels of solar radiation to fluctuate. When the Sun emits more intense ultraviolet (UV) light, specifically the strong hydrogen Lyman-alpha emission, more clouds appear on Neptune about two years later. The team further found a positive correlation between the number of clouds and the ice giant’s brightness from the sunlight reflecting off it.

“These remarkable data give us the strongest evidence yet that Neptune’s cloud cover correlates with the Sun’s cycle,” said de Pater. “Our findings support the theory that the Sun’s UV rays, when strong enough, may be triggering a photochemical reaction that produces Neptune’s clouds.”

The graph to the right shows the correlation between the clouds and the sunspot cycle. The paper is available here.

This conclusion remains uncertain because of the overall sparseness of the data. Yet, it is intriguing, and also underlines the importance of the Sun on the Earth’s climate. If the solar cycle can impact Neptune’s climate so significantly from 2.8 billion miles away, it certainly must have a major impact on the Earth’s climate at only 100 million miles distance.