Why is the sun going quiet?

Jan 22, 2014 by Brad Carter, The Conversation
What’s going on up there? Credit: VinothChandar

The sun is our nearest star and the source of all our light and heat on Earth but recent reports have highlighted an ongoing steep decline in solar activity.

This story is a reminder that our is a variable star whose dynamic production of magnetism, activity and winds have implications for our planet.

Solar magnetic fields power solar activity, including sunspots, explosive events known as solar flares and , and an outward-flowing solar wind.

The sun's activity and wind bathes Earth in a changing space environment of high-energy radiation and fast-moving particles called "space weather". This gives us both the beauty of the aurorae and disruptive effects on communications and other technology.

Solar activity varies over time, with the 11-year sunspot cycle being the most familiar example. Solar activity also varies more widely over longer timescales, producing "grand maxima" and "grand minima".

Credit: NASA

The most famous of these is the Maunder minimum in sunspot activity from around 1645 to 1715.

The current rate and extent at which solar activity is falling has been interpreted as the beginning of another grand minimum, and raises the issue of what it means for Earth's climate.

The convoluted magnetic field lines extending from the sun. Credit: NASA

Variations in solar activity have long been linked to climate variability on Earth, with the most familiar historical example being the Maunder minimum. This corresponded to relatively cold climatic conditions described as the "Little Ice Age" when rivers that were normally ice-free froze and snow fields remained year-round at lower altitudes.

Question of how solar activity influences the Earth's climate remains the subject of ongoing research. What is becoming clearer is that variations in solar ultraviolet radiation resulting from solar activity can provide a physical mechanism for the Sun to influence the Earth's atmosphere.

However, it is important to understand that research also indicates that these solar effects are minor compared to modern-day anthropogenic effects. Even if there is measurable cooling, a grand minimum should not be relied upon to slow global warming.

Climatic effects aside, a grand minimum in solar activity would mean reduced auroral displays, and some lessening of the hazards caused by for spacecraft, and any occupants.

Why the fluctuations?

The answer lies in how the sun generates its .

As a typical star our sun is a ball of hot gas, more than a hundred times the diameter and hundreds of thousands of times more massive than the Earth.

Inside the sun, the effects of heat, pressure and motion produce electrical currents that in turn generate magnetic fields. This solar dynamo results in magnetic fields emerging from the sun's visible surface to power its activity and winds and the space weather experienced by Earth.

Explaining the variable nature of comes down to understanding the physics of the solar dynamo. At present there is a general theoretical picture of how the dynamo can produce magnetic fields and even cycles.

What is less certain is how the dynamo changes into the special state that corresponds to grand minimum, and whether such occurrences are to some extent predictable or purely random.

One way to learn more about the sun and its dynamo is to study other stars. Dynamos occur in many other stars, so observations of stars of different ages can offer clues regarding the past and future of solar magnetism and its effects. These magnetic studies of stars and their activity and winds can be used to better test the predictions of dynamo theory.

An improved understanding of stellar dynamos may then help us know more about what is happening to the sun today, and perhaps provide a useful tool to forecast future changes in our variable sun.

Explore further: NASA's SDO sees giant January sunspots

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User comments : 16

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PsycheOne
2.3 / 5 (19) Jan 22, 2014
"However, it is important to understand that research also indicates that these solar effects are minor compared to modern-day anthropogenic effects. Even if there is measurable cooling, a grand minimum should not be relied upon to slow global warming."

They had to sneak in a reference to their religion, didn't they?

So the phenomenon that caused the little ice age should have little effect on global warming which has accounted for, what, less than one degree of change in 100 years and none in the last 16.

I see. Let us pray.
shavera
4.1 / 5 (17) Jan 22, 2014
Right, so if the sun is going into a minimum, we should *expect* to be seeing cooling, ne pas? And yet we're seeing warming, including over the last 16 years when you include ocean data and not just "surface" temperatures. So it would seem to me, that whatever is going on driving warming is a greater effect than the sun's cooling cycle. It's fairly simple logic. One step down from the sun, 2 steps up on the earth still puts us a step up.
GSwift7
4.1 / 5 (7) Jan 22, 2014
They had to sneak in a reference to their religion, didn't they?


I'm sure they would get piles of hate mail if they didn't. Anyway, who cares? That doesn't bother me in the least.

The rest of the story was interesting. Did you notice that the bold hyperlinks in the story actually take you to good references? The non-bold links are the typically useless physorg links, but the original author must have inserted those other links. I love it when they do that, so kudos to Brad Carter.

If we do get another grand minimum, and if it does give us another extended cold spell, then I'm glad I live in South Carolina. Places like the upper midwest are already unbearable in the winter. I'd hate to see it get even colder there.

I moved here from Kansas City. They have the worst of both worlds; Summer hotter than here (we get fewer +110 days), and cold, windy, icy winters too. The midwest sucks for weather!
GSwift7
3.9 / 5 (10) Jan 22, 2014
And yet we're seeing warming, including over the last 16 years when you include ocean data and not just "surface" temperatures.


I agree with you in principle, but you have to be careful with switching data sets out of convienience. If you're going to use the ocean+air record for the past 16 years, then you've gotta compare it to the ocean+air record for the past 2 centuries. You can't compare one to the other on different time periods as that has no meaning.

I think you could more effectively rebutt PsychOne's comment by pointing out that it doesn't matter whether it's actually risen in the past 16 years or not. If you accept the simple surface air temp record, then it is true that it hasn't risen recently. BUT it hasn't cooled, has it?

Besides, the long term records all show that long trends in climate cannot be seen in time periods shorter than 30 years, so 16 years is meaningless without comparison to the next or previous 16 years.

There's no issue here.
Scroofinator
2 / 5 (7) Jan 22, 2014
Another caveat to the current reduction were seeing: How does this affect the ionosphere? It's my belief that a charged up ionosphere (from CMEs) helps to stabilize the climate. Like the article said, the last time this happened we plunged into a mini ice age. Some theories on the great pyramids actually say they were power plants to keep the ionosphere charged up to stabilize the climate. It really doesn't seem all that crazy to me, after all, Tesla's grand solution was using the ionosphere.
The Shootist
2.3 / 5 (9) Jan 22, 2014
Still waiting to farm dairy cows in Greenland.
Nestle
1 / 5 (9) Jan 22, 2014
IMO the large cloud of dark matter at galactic plane is passing through solar system (compare the IBEX observations). It shifts the barycenter of solar system beneath the surface of Sun, which inhibits the circulation of solar plasma with Corriolis force there. The same cloud is responsible for global warming too, IMO.
Nestle
1 / 5 (8) Jan 22, 2014
The fluctuations of gravity constant and dilatation of meter and kilogram prototypes are of the same origin, IMO. More dense vacuum means less dense and gravitating matter. The changes in speed of light and motion of Moon-Earth system and speed of rotation of Earth can be observed too..
Maggnus
4.5 / 5 (10) Jan 22, 2014
Zephyr, I am assuming you changed you name again because your last group of sock puppets got banned, probably because of multiple off-topic posts. So why start it up again?

Even if this is not the case, continually posting your tired aether "theory" in successive multiple posts on every article will lose you any audience you currently enjoy. Instead of trying to shove your theory down our collective throats, how about you try just joining in the conversation?
ryggesogn2
1.7 / 5 (12) Jan 22, 2014
"Variations in solar activity have long been linked to climate variability on Earth, "
Not according to AGWites.
Grallen
4.2 / 5 (6) Jan 23, 2014
If it really is going into a "Grand Minimum", this is a perfect time to expand our presence in space.

It's really convenient considering private entities just getting into the space game recently.

I wish we could get the political momentum to try to build something crazy like... any of these:
http://en.wikiped...celaunch

Yes I know, money. But worth it (if it panned out...).
Whydening Gyre
3 / 5 (2) Jan 23, 2014
I wish we could get the political momentum to try to build something crazy like... any of these:
http://en.wikiped...celaunch

Yes I know, money. But worth it (if it panned out...).

Two words. Atmospheric friction. Would have to be built pretty high up in atmosphere to eliminate the major part of that. Would still need some aerodynamic lift capability after that. To finish the job (the to orbit arc)you'd need scramjet....
NASA would have to move to the Himalayas... China could build it...
Wait, this sounds like a movie...
alfie_null
4.2 / 5 (5) Jan 23, 2014
If we are entering a new grand minimum, and it is countering the effects of AGW, it would be interesting to try to understand the additive effect on the change in climate as we emerge in what, another 60 years or so. Wonder if we'll yet still be doing stuff like burning coal? Guess it's not my problem though. Sorry, kids.
ryggesogn2
3 / 5 (4) Jan 24, 2014
The question, "Why is the sun going quiet?" wasn't answered.
Nestle
2.2 / 5 (5) Jan 24, 2014
Because nobody actually knows this answer. We can just collect and judge hypothesis. The best approach is to ask, why the Sun isn't always quiet. Under normal conditions the solar cycle maintains eleven years long period, which is not accidental at all - it fits the orbital period of Jupiter planet.

How the Jupiter affects the solar cycle? Well, it can only change the location of center of mass (barycenter) of solar system. When it does counterbalance the (mass of) other planets, the barycenter appears bellow the surface of Sun. This eliminates the Corriolis force, which contributes to circulation of solar plasma bellow or above the solar equator in similar way, like for the atmosphere of the Earth. Under such a situation the solar plasma behaves like the water inside of cup placed into microwave without stirring. The Sun generates heat, but this heat cannot circulate - and the solar plasma gets overheated. It forms magnetic vortices similar to bubbles, which are known as a sunspots.
Nestle
1.3 / 5 (4) Jan 24, 2014
When the barycenter appears outside of Sun, the circulation of solar plasma becomes asymmetric to it and the Corriolis force may apply again. The current of solar plasma beneath the solar surface is dragged bellow or above the equator and it drags the sunspots accumulated inside of it. The sunspots are raising toward surface and popping here like bubbles. It induces the solar protuberances and solar quakes and other activity.

The best evidence of this model is in consideration of motion of another planets (Saturn, Neptune), which can contribute to barycenter location. It introduces another regularity into solar cycle, like the Gleissberg cycle with median period of 88 years. These additional cycles are well recognizable on frequency spectrum of sunspot frequency or radionuclide changes in ice deposits.

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