The Sun in more active times: Sunspot activity, which is linked to weather and other phenomena on Earth, peaked in 2001. But for the last two years there’s been almost nothing.
Courtesy NASA
Our Sun has been burning brightly for some five billion years. But the rate of its burning has not been steady. The Sun goes through a regular 11-year cycle of active periods and quiet periods. The active periods are marked by an increase in sunspots—dark regions of intense magnetic activity on the surface of the Sun.
Now, “active” and “quiet” are relative terms. The amount of energy released by the Sun in its “active” phase is only 1/10th of 1% more than that released during its “quiet” phase. In other words, a quiet Sun is still putting out 99.9% as much energy as an active Sun.
Yet, scientists have long noted a connection between activity on the Sun and temperatures here on Earth. (We have discussed this phenomenon before, here and here.) And the impact is much greater than that 1/10th of 1% would have you believe. How could such a small increase in solar output have such a large effect on Earth?
Well, it looks like we finally have an answer. A new study by the National Center for Atmospheric Research and published in the journal Science argues that the increased solar output warms ozone in the upper atmosphere. This extra energy creates more ozone, which traps more heat, which creates more ozone, which… you get the idea. It’s a feedback loop. The end result is stronger winds. These winds reduce clouds over the Pacific Ocean, allowing it to warm up as well. So you’ve got heat coming down from the sky, and more heat coming up from the ocean, the end result of which is that the Earth warms more than twice as much as you would expect from the increased Sun activity alone.
(The low number of sunspots over the last couple of years may at least partially explain our unusually cool summer.)
The researchers are careful to say that this work does not explain long-term climate change, but simply periodic weather patterns. However, sunspots have been linked to major climate events of the past, such as the Little Ice Age. Finding the exact mechanism of their influence may simply be a matter of more research.
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Sun with sunspots
Courtesy NASA
One of the most common questions I hear about climate change is "Isn't it just the sun?" Days (sun out) are warmer than nights (no sun), and sunny days are usually warmer than cloudy days. Let's be honest, it would also be much easier on the conscience. After all, we have about as much chance of controlling the sun as I do of getting my cat to do the laundry. But our actions do impact the amount of carbon dioxide in the atmosphere.
Scientists who are interested in climate have been looking into this. A new paper by Anja Eichler and her colleagues from Switzerland and Russia looks at this problem by comparing records of how brightly the sun has been shining to the temperature in central Asia over the last 750 or so years. Now you're probably thinking, "Hey, who had a thermometer in Siberia 750 years ago?" It turns out that the part of Siberia near Mongolia and Kazakhstan has glaciers that are actually pretty good at recording the temperature.
So what'd they find? The sun is pretty important. It explains well over half of the wiggles in the temperature curve . . . until 1850. After that the sun is still kind of important, but changes in the amount of carbon dioxide in the atmosphere do a much better job explaining the recent warming.
Other scientists have found the same story using different methods, so I think we're homing in on a solid answer.
If you want to read the paper yourself, it is in press in Geophysical Research Letters. The story's not free on-line, so you might need to head to a library to check it out.
Investigations into the 2007 collapse of the I-35W bridge are wrapping up and being reported. Here's an interesting report on what role the sun and its energy may have played in the timing of the bridge's collapse on that fateful Aug. 1 day. Oh, and my apologies to Elton John for swiping his lyrics for the headline of this post.
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Sunspot activity reaches record low
in Earth and Space Science, The Water Cycle, Weather and Climate, and The Universe
Where, oh where, have my sunspots gone?: Sunspot activity tied a record low of zero in August, 2008.
Courtesy NASA
For the first time in almost a century, the Sun has a spotless record. There were no observed sunspots in August. None. Zero. Zip. Can't get a record any lower than that. That's the first time this has happened since 1913.
That's before commercial radio. Before talking movies. Before World War I. Why, it's almost as long as since the last time the Cubs won the World Series.
Now, that's a long time!
Plus, as we've discussed before, the Sun has been unusually quiet of late. Sunspots generally go through an 11-year cycle, and we're a couple years late for the next rise in activity.
But, you are no doubt wondering, what does this mean to me, the Average Joe? (Assuming your name is indeed "Average Joe," which would be pretty remarkable and, ironically, not average.) Well, sunspots seem to be tied to weather. Three times, since astronomers began observing suspots, has the Sun fallen silent, and each time coincides with significant drops in global temperatures. One such dip, from roughly 1600 to 1750, was so severe it is known as "The Little Ice Age."
Are we heading into another glacial period? Much too soon to tell. But if you start feeling chilly, keep your eye on the Sun. Astronomers will be doing the same.
(NOTE FOR THE METAPHORCALLY-IMPAIRED: That was meant figuratively. Do not look directly at the Sun with your naked eye. You'll burn out your retina.)
Is it hot in here, or is it just me.: Research and debate continues on global warming. Image by ! "S4N7Y" !
(With the Republican National Convention literally across the street, the Science Museum of Minnesota will be closed starting Friday, August 29. But Science Buzz marches on! To honor our convention guests, I’ll be posting entries focusing on issues where science and politics overlap. Hopefully this will spur some discussion. Or at least tick some people off.)
Let’s start with a nice, safe topic. Like global warming. Because Lord knows, we haven’t discussed that enough.
We recently passed an important milestone in the climate change debate: it was 20 years ago this summer that global warming became a political issue in America, thanks to NASA’s Jim Hansen testifying before Congress. (Some wags have noted that the global temperature in June 2008 was cooler than in June 1988--but that’s weather, not climate.)
There was a dust-up recently concerning the American Physical Society, a leading scientific organization. One of its units, the APS Forum, published a paper by Christopher Monckton arguing that carbon’s impact on climate has been greatly overstated. The Forum intends to publish additional papers in its journal, Physics and Society, as part of a public debate on global warming science.
Some in the news media inaccurately reported that the APS itself had reversed its stance on global warming. This was not the case—the society as a whole maintains that human activity is the main cause of recent climate change. The journal is put out by APS Forum, which is just one of 19 units within the larger organization. But at least they are willing to have the debate.
Meanwhile, Australian astronomer Ian Wilson is predicting global cooling. His research finds that the main driver of Earth’s climate is the Sun’s activity, and that has been decreasing of late.
Aurora mystery comes to light
in Earth and Space Science, Physical Science, Energy Transformations, and Forces of Nature
Northern Lights over Minneapolis: Aurora borealis dance over Lake Harriet, November 6, 2004
Courtesy Mark RyanMany years ago, three friends and I were heading home from a road trip to western Canada. It was about 2:30 in the morning, and I was driving while everyone else was sleeping. I was probably half-asleep myself. But as we chugged along Highway 2 near the outskirts of Bemidji, Minnesota, something in the upper corner of the windshield caught my eye. When I looked up, the sight was so spectacular I immediately pulled over and woke everyone up to see it. My friends were none too happy as I coaxed them out of the van into the cold northern Minnesota night.
Above us, the night sky was alive with the most incredible display of the Northern Lights I have ever witnessed. Bright, vibrant fingers of yellow, blue, red, and green light spread out from a point overhead, like a brilliant hand reaching down from the black sky. I’ve never seen colors like that since. The display was something I’ll never forget and it’s hard to convey how beautiful it actually was, but let me just say my friends soon discarded any thoughts of pummeling me with their fists.
Now, scientists have figured out the mystery behind the phenomenon. According to a new study published in the journal Science, the catalyst of the aurora borealis (and their southern counterpart aurora australis) takes place way out in space about 80,000 miles from Earth during an event called magnetic reconnection.
"Our data show clearly and for the first time that magnetic reconnection is the trigger," said Vassilis Angelopoulos, the project’s principal investigator. "Reconnection results in a slingshot acceleration of waves and plasma along magnetic field lines, lighting up the aurora underneath even before the near-Earth space has had a chance to respond."
The data was gathered by five strategically positioned satellites (a NASA mission known as THEMIS) and compared with that from ground-based detectors.
The process actually begins on the Sun. Turbulent activity on its surface sends out massive energy bursts via the solar wind that interact with the Earth’s magnetic fields and cause all sorts of havoc with our power grids and communication networks. They also create wonderful auroras. But these massive solar outbursts are only occasional, occurring maybe 10 times a year. More frequently – about every three or four hours - the geomagnetic fields are bombarded by substorms; smaller energy bursts that also create auroras. But don’t let the diminutive name deceive you. The energy generated by each substorm is huge, anywhere between one million to two million amps over one or two hours. The THEMIS project determined that, during substorms, the Earth’s magnetic field lines are stretched out like rubber bands building up tremendous amounts of energy before suddenly snapping and flinging charged particles back toward the Earth’s poles. The results are the dancing auroras seen in the northern and southern regions.
Magnetic reconnection is common throughout the known Universe and has been suspected by many as the trigger of auroras. For three decades, though, a competing theory argued the auroras were triggered much closer to Earth, by the disruption (or short-circuit) of charged ions interacting with the magnetic field.
But the new data seems to show otherwise. During a substorm studied in February, the satellites’ data showed the magnetic reconnection occurred first, followed soon after by an aurora display. Only after the display was the short-circuit observed.
Looks like the 30-year debate may be over.
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The Sun in more active times: Sunspot activity, which is linked to weather and other phenomena on Earth, peaked in 2001. But for the last two years there’s been almost nothing.
Courtesy NASA
Occasionally, intense magnetic activity in the Sun creates sunspots, dark regions on the surface of the Sun. Sunspot activity rises and falls roughly every 11 years – the last maximum was in 2001, and activity slowly fell off to zero by 2006.
And since then…almost nothing. Scientists had expected sunspot activity to start increasing by now, but it hasn’t. No one knows why, or when the cycle will pick up again.
Why is this important?
Sunspots, created by intense magnetic activity, are associated with solar flares, enormous streams of high-energy particles sent shooting out into the Solar System. These play havoc with satellites and other electronic communication. So, no sunspots in this case would be a good thing.
Solar flares also create the beautiful northern and southern lights. In this case, no sunspots is a bad thing.
Perhaps most important, sunspots seem to be an indicator of solar activity. And low activity can mean lower temperatures here on Earth. The Sun once went 50 years without producing any spots – from 1650 to 1700 – and these years were some of the coldest in recorded history. Today they are known as the little Ice Age.
Are we on the brink of a new Ice Age? It’s wayyyy to early to tell. But scientists are keeping an eye on the Sun, to see if it reveals any clues.
The big D: Research continues to shed light on the role vitamin D plays in our bodies.
Courtesy Leo Reynolds
We've talked beforeon Science Buzz about the link between sunlight, vitamin D and cancer. Well, the story just won't go away...
Here's more evidence that sunlight = vitamin D = a healthier life.
And research that shows vitamin D can reduce the risk of diabetes.
And also reduce risk of a heart attack.
But, just to keep things balanced, here's a report that vitamin D doesn’t do everything – some of the health benefits claimed for the vitamin don’t stand up to research
And here’s a summary of the pros and cons of vitamin D and sun exposure.
Australian scientists studying albedo--the amount of sunlight reflected off the Earth—have created a flat cardboard kangaroo 105 feet tall. Photographing the image from space will give clues to how the Earth’s atmosphere heats up and cools down.
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Science Buzz is supported by the National Science Foundation.Copyright © Science Museum of Minnesota, 2004-2010, except where noted.
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