Are Sunspots Disappearing?

Sep 03, 2009
Sunspot magnetic fields measured by Livingston and Penn from 1992 - Feb. 2009 using an infrared Zeeman splitting technique.

The sun is in the pits of the deepest solar minimum in nearly a century. Weeks and sometimes whole months go by without even a single tiny sunspot. The quiet has dragged out for more than two years, prompting some observers to wonder, are sunspots disappearing?

"Personally, I'm betting that sunspots are coming back," says researcher Matt Penn of the National Solar Observatory (NSO) in Tucson, Arizona. But, he allows, "there is some evidence that they won't."

Penn's colleague Bill Livingston of the NSO has been measuring the fields of sunspots for the past 17 years, and he has found a remarkable trend. magnetism is on the decline:

"Sunspot magnetic fields are dropping by about 50 gauss per year," says Penn. "If we extrapolate this trend into the future, sunspots could completely vanish around the year 2015."

This disappearing act is possible because sunspots are made of magnetism. The "firmament" of a sunspot is not matter but rather a strong that appears dark because it blocks the upflow of heat from the sun's interior. If Earth lost its magnetic field, the solid planet would remain intact, but if a sunspot loses its magnetism, it ceases to exist.

"According to our measurements, sunspots seem to form only if the magnetic field is stronger than about 1500 gauss," says Livingston. "If the current trend continues, we'll hit that threshold in the near future, and solar magnetic fields would become too weak to form sunspots."

"This work has caused a sensation in the field of solar physics," comments NASA sunspot expert David Hathaway, who is not directly involved in the research. "It's controversial stuff."

The controversy is not about the data. "We know Livingston and Penn are excellent observers," says Hathaway. "The trend that they have discovered appears to be real." The part colleagues have trouble believing is the extrapolation. Hathaway notes that most of their data were taken after the maximum of Solar Cycle 23 (2000-2002) when sunspot activity naturally began to decline. "The drop in magnetic fields could be a normal aspect of the and not a sign that sunspots are permanently vanishing."

Zeeman splitting of spectral lines from a strongly-magnetized sunspot.

Penn himself wonders about these points. "Our technique is relatively new and the data stretches back in time only 17 years. We could be observing a temporary downturn that will reverse itself."

The technique they're using was pioneered by Livingston at the NASA-supported McMath-Pierce solar telescope near Tucson. He looks at a spectral line emitted by iron atoms in the sun's atmosphere. Sunspot magnetic fields cause the line to split in two—an effect called "Zeeman splitting" after Dutch physicist Pieter Zeeman who discovered the phenomenon in the 19th century. The size of the split reveals the intensity of the magnetism.

Astronomers have been measuring sunspot magnetic fields in this general way for nearly a century, but Livingston added a twist. While most researchers measure the splitting of spectral lines in the visible part of the sun's spectrum, Livingston decided to try an infra-red spectral line. Infrared lines are much more sensitive to the Zeeman effect and provide more accurate answers. Also, he dedicated himself to measuring a large number of sunspots—more than 900 between 1998 and 2005 alone. The combination of accuracy and numbers revealed the downturn.

If sunspots do go away, it wouldn't be the first time. In the 17th century, the sun plunged into a 70-year period of spotlessness known as the Maunder Minimum that still baffles scientists. The sunspot drought began in 1645 and lasted until 1715; during that time, some of the best astronomers in history (e.g., Cassini) monitored the sun and failed to count more than a few dozen sunspots per year, compared to the usual thousands.

"Whether [the current downturn] is an omen of long-term sunspot decline, analogous to the Maunder Minimum, remains to be seen," Livingston and Penn caution in a recent issue of EOS. "Other indications of solar activity suggest that sunspots must return in earnest within the next year."

Whatever happens, notes Hathaway, "the sun is behaving in an interesting way and I believe we're about to learn something new."

Source: Science@, by Dr. Tony Phillips

Explore further: US-India to collaborate on Mars exploration

add to favorites email to friend print save as pdf

Related Stories

The Sun Shows Signs of Life

Nov 10, 2008

After two-plus years of few sunspots, even fewer solar flares, and a generally eerie calm, the sun is finally showing signs of life. "I think solar minimum is behind us," says sunspot forecaster David Hathaway ...

What's Wrong with the Sun? (Nothing)

Jul 11, 2008

Stop the presses! The sun is behaving normally. So says NASA solar physicist David Hathaway. "There have been some reports lately that Solar Minimum is lasting longer than it should. That's not true. The ongoing ...

Is a New Solar Cycle Beginning?

Dec 17, 2007

The solar physics community is abuzz this week. No, there haven't been any great eruptions or solar storms. The source of the excitement is a modest knot of magnetism that popped over the sun's eastern limb ...

Solar Minimum Explodes

Sep 16, 2005

Just one week ago, on Sept. 7th, a huge sunspot rounded the sun's eastern limb. As soon as it appeared, it exploded, producing one of the brightest x-ray solar flares of the Space Age. In the days that followed, ...

Long-standing sunspot puzzle solved

Aug 19, 2009

(PhysOrg.com) -- Scientists at the Universities of Glasgow, Strathclyde and Central Lancashire have used 21st Century solar observations and image processing to finally solve a sunspot puzzle first noticed ...

Recommended for you

US-India to collaborate on Mars exploration

7 hours ago

The United States and India, fresh from sending their own respective spacecraft into Mars' orbit earlier this month, on Tuesday agreed to cooperate on future exploration of the Red Planet.

Swift mission observes mega flares from a mini star

7 hours ago

On April 23, NASA's Swift satellite detected the strongest, hottest, and longest-lasting sequence of stellar flares ever seen from a nearby red dwarf star. The initial blast from this record-setting series ...

Sandblasting winds shift Mars' landscape

12 hours ago

High winds are a near-daily force on the surface of Mars, carving out a landscape of shifting dunes and posing a challenge to exploration, scientists said Tuesday.

PanSTARRS K1, the comet that keeps going

14 hours ago

Thank you K1 PanSTARRS for hanging in there! Some comets crumble and fade away. Others linger a few months and move on. But after looping across the night sky for more than a year, this one is nowhere near ...

User comments : 15

Adjust slider to filter visible comments by rank

Display comments: newest first

ReimannNoodle
2.5 / 5 (8) Sep 03, 2009
And not one word in this article about how this relates to climate. Could this be the reason those "global warming" (you know, before they changed it to "climate change") predictions are being proven so wrong? Or why the rest of the solar system has been tracking along with our warming and now cooling? Hmmmm...
Knightraptor
2.7 / 5 (9) Sep 03, 2009
You've got it all wrong. The Earth is the CAUSE of the decrease in sunspot activity. Obviously our carbon emissions are somehow causing harm to the sun through an inter-dimensional link that exists between the earth and the sun. Duh.
Snake
5 / 5 (3) Sep 03, 2009
http://en.wikiped..._Minimum

"the Maunder Minimum coincided with a period of lower-than-average global temperatures".
omatumr
1.9 / 5 (9) Sep 03, 2009
NASA AWAKENS, THE SUN FALLS ASLEEP, AND PLANET EARTH COOLS

Yes, of course, and that's no coincidence!

Earth's climate is tightly linked with solar cycles of magnetic surface activity and sunspots.

See: "EARTH'S HEAT SOURCE - THE SUN", Energy and Environment 20 (2009) 131-144 http://arxiv.org/pdf/0905.0704

The standard solar model of a Hydrogen-filled Sun does not explain cycles of solar activity and NASA has refused to consider data over the past four decades (since the 1969 Apollo Mission to the Moon) that showed the standard solar model of a Hydrogen-filled Sun is obsolete.

With kind regards,
Oliver K. Manuel
http://www.omatumr.com
ArtflDgr
3 / 5 (6) Sep 04, 2009
any one besides me want to start a new college to earn money on this trend? we can call it chicken little University. where we teach that everything kills, and it could be tomorrow... (so eat drink and be merry -- correction, cower in a corner and panick).

turn on the documentary channels and all you get is a rock from space will kill us, global warming will kill us, pandemic will kill us, bizarre weather will kill us, we will kill us, see a trend?

basically if one wants to be funny, one can claim that god has a wicked sense of humor and has created a maunder type minimum to just screw with the communists/socialists... :)
3432682
1.6 / 5 (7) Sep 04, 2009
If you ever doubted the propaganda mission of this site and all the other "scientific consensus" sites, reconsider. Nothing to see here folks, just keep moving along. Pay no attention to the socialists behind the curtain.
moj85
not rated yet Sep 04, 2009
haha knightraptor i give you a boon of credit for sheer gaul. and hilarity ;D
david_42
not rated yet Sep 05, 2009
If there is an underlying slightly-longer-term sunspot cycle of approximately 350 years, 17 years of data will look like a straight line regardless of where in the cycle you are taking your data.

I say slightly-longer-term, because in the life-cycle of a sun there is little difference between 23 years and 350.
Sirussinder
not rated yet Sep 06, 2009
2012 is just around the corner.....
aufever
3 / 5 (2) Sep 06, 2009
Amazing, this is the missing element in all the Computer Models on Climate. I love to watch some braindead scientist hold up a piece of permafrost that has recently thawed and proclaim that this is due to Man Caused Global Warming and lo and behold, the mass is held together by roots that formed when the area was warm enough to sustain plant growth. Another Miracle, how did all those Methane Hydrates Form? We have yet to approach the temperature levels that existed when Eric the Red Colonized Greenland around 1050.
docknowledge
1 / 5 (1) Sep 06, 2009
We have yet to approach the temperature levels that existed when Eric the Red Colonized Greenland around 1050.


...and when the temperatures go up a little more...you have the same line..."There was a period in 50 BC that was hotter". Or how about "these temperatures are all within three standard deviations of recorded norm"?

Hey, wanna buy some property in CA that was turning into dense forest when we bought it, but now we're afraid is going to burn to permanent shrub?
dachpyarvile
3 / 5 (2) Sep 06, 2009
The Sun has been spotless since July 11, 2009, according to the current MDI Continuum data from SOHO.

When the temperatures go to more than 5°C higher than they are currently, that is the time that I might, I say might, start worrying.

Until then, it is a waste of time to panic, especially when archaeological evidence (which evidence the IPCC ignores and others try to downplay) does show that temperatures in the Arctic were higher on the order of between 4-5°C than today.
rwinners
not rated yet Sep 11, 2009
I'd guess that for statistical purposes, the sampling is way, WAY to small.
dachpyarvile
1 / 5 (1) Sep 11, 2009
Or, the graph is compressed.
dachpyarvile
1 / 5 (1) Sep 13, 2009
There was a little sunspot that is reported to have emerged late on August 31, 2009 but the clip was not included in the dataset for some reason. But,...

Nevertheless, it is likely that the current year's number of blank days will be the longest in about 100 years. It is not shown many signs of picking up the pace so far.


(From the current September 4, 2009, "pick of the week" page on the SOHO site).