April 16, 2014

21.04.11: Of Alien Flora and Maunder Minimums.

Sol picking up in activity… (Photo by Author).

Some fairly thought provoking science has been coming out of the Royal Astronomical Society’s National Astronomy Meeting being held this week in Llandudno, Wales. One of the most interesting talks was by Dr. Robert Forsyth of Imperial College concerning a comparison of the current solar lull and the famous Maunder minimum of 1645-1715. [Read more...]

03.03.11: The Riddle of the Blank Sun: Solved?

A spotless Sol… (Photo by Author).

   Researchers At the Indian Institute of Science and Education and the Harvard-Smithsonian Center for Astrophysics may have shed light on an enduring mystery from the past decade. In an article due to be published today in Nature, Dibyendu Nandi and co-author Andre Munoz-Jaramillo have come up with convincing evidence as to why the past solar minimum of 2008-09 was such a persistent one. During this minimum, over 600 spotless days occurred, the most since the great minimum of 1913. As a result, the outer magnetic sheath of the sun that we reside in shrunk, the Earth’s upper atmosphere cooled due to lower ultraviolet levels and contracted, and an increase of cosmic ray activity was seen in the inner solar system. This subsequently affected the usual drag that is induced on satellites, slowing down the rate of orbital decay and causing a buildup of space junk… just what’s up with our nearest star?

   Now, researchers have built a model of the solar interior that fits a description of what has actually occurred; and the trouble started back at the peak of cycle #23 with a speeding up of the “Great Conveyor Belt” of plasma in the suns interior. This magnetic dynamo sub-ducts sunspot activity towards the poles, only to have them “well up” as these conveyors turn in opposite directions in both hemispheres. Paradoxically, a slowing down leads to a relaxing and expansion of the belt, allowing magnetic activity to surface; speeding up meant the activity never had a chance to surface. Sunspot activity usually begins at high latitudes at the beginning of a cycle, a hallmark that the new cycle is indeed underway. As the sunspot cycle progresses, sunspot activity tends to progress to lower latitudes. The model suggested by Nandi and Munoz is built on the buoyant evolution of sunspots versus the interplay of the magnetic dynamo and the meridional flows in the solar interior. This theory may also explain two other lingering mysteries; why are sunspots never seen at polar solar latitudes? Does the sun have longer cycles juxtaposed over the known 11 year one, such as the 70 year cycle that occurred in the 17th century known as the Maunder Minimum?

   Researchers will soon have a chance to put all of these models to the test. NASA’s Solar Dynamics Observatory is on solar vigil, and the twin STEREO spacecraft have reached a vantage point giving scientists 360° coverage of the Sun. Solar cycle #24 will see the sun scrutinized as never before. Even today, two new sunspot groups have emerged, and a large prominence looking like an acacia tree can be seen on the limb of the sun from Astroguyz HQ via our trusty PST… the approaching 2013-14 solar maximum may prove to mark a renaissance in solar science.      


Review: The Sun Kings by Stuart Clark


We here at Astroguyz love a good read about the “secret history” of astronomy… sure, everybody knows the exploits of Galileo and Copernicus, but how many have heard of the trials of 18th century British astronomer Richard Carrington? The Sun KingsThe Unexpected Tragedy of Richard Carrington and the Tale of How Modern Astronomy Began, by Stuart Clark  and out now by Princeton University Press is the fascinating tale of how the science of astrophysics and space weather truly began, and of how astronomers went from passively observing to truly analyzing data gleened from the universe around us. A truly rare and engaging breed of science history book, we were almost sad to finish it. It stands probably as the best read we’ve had since The Search for Planet Vulcan, and tells how these old-time astronomers operated.

The tale opens with the now infamous Halloween flares of 2003, some of the most powerful of the previous solar cycle. This represented the first time that some of our most cherished solar watch dogs, such as SOHO and the GONG  network were on hand to witness the full fury of the Sun. The shock was even felt by our vanguards elsewhere is the solar system, such as the Ulysses, Voyager 2, and Mars Odyssey spacecraft, even burning out the radiation detectors on the latter!

But as with much in science, our interpretation and understanding took a long and torturous road. The book then whisks the reader back to late 18th century England, a time when William Herschel proposed an astonishing idea; that the observed 11 year sunspot cycle was linked to Earthly agriculture and commerce. Specifically, he noted that the price of wheat tended to fluctuate in a corresponding period, with prices at their highest and supplies at their scarcest during the solar minimum and the opposite occurring at the solar max. Of course, this was seen as the delusion of an aging astronomer and roundly dismissed by his peers. Herschel had discovered Uranus and the infrared part of the spectrum, but this third contribution was largely overlooked.

Enter Richard Carrington. He stands as the kind of guy you’d always root for, an astronomer of ambition and insight whose personal life was marred by tragedy. He’s is now remembered mostly for being on hand and having the prescience to accurately record what he saw, but also made the right connections to what was going on around the environs of the Earth in late 1859.  It was interesting to note that during the height of the electromagnetic turbulence, a telegraph operator in Portland, Maine noted that his transmission system worked better utilizing solely the charge on the line, with the batteries disconnected!

Carrington’s prime ambition was to observe the Sun through the span of one complete solar cycle, but like many of us, his plan to pursue astronomy was continuously be-deviled by the pursuit of funding and that whole “personal life” thing.  Perhaps he needed a blog…

First, the death of his father left him running the family brewery. Not that the title of “Gentleman/ Brewer/ Astronomer” is a bad byline… but his romantic exploits turned sour as well, when his marriage to an under class woman turned into a love triangle that pulls him into trial and scandal. The whole affair reads like a bad Jane Austin novel… unfortunately,  the innocent Carrington took his life by overdose of chloral of hydrate mixed with alcohol shortly after the death of his wife Rosa.

As sad a fate as Carrington’s life was, his insight sparked a vigilant monitoring of the Sun. In fact, in the late 19th century, the riddle of the Sun was the topic in astronomy, as scientists turned a battery of new toys on our nearest star, such as the spectroheliograph and that new fangled device, the camera.

Hereto unknown elements such as helium  were first discovered in the atmosphere of the Sun. But the source of its enormous energy output had to remain and mystery until Einstein revealed the miracle of fusion in the early 20th century.

Enter Edward Walter Maunder, in many ways the intellectual predecessor to Carrington. From his early childhood, Maunder had been transfixed by the Sun, spying a naked eye sunspot as a boy through a low heavy fog. It must have been an astonishing sight to the young Carrington, who went on to lead an expedition to India in 1898 to photograph the elusive solar corona.

Images taken by his wife Annie, an expert astronomer in her own right,  later confirmed the connection between the tenuous streamers seen and sunspot activity. Here finally lay the mechanism by which the Sun could reach out and touch the Earth.

But its for another fascinating theory that Maunder is now known. He noted during his historical research that large spans of spotless periods corresponded with eras of dramatic global climatic cooling; a famous stretch from 1645 to 1715 now bears his name as the Maunder Minimum. During this period, the Thames river froze annually, harvests were meager, and several “years without a summer” were recorded. At first, even Maunder himself was skeptical; he believed the apparent lack of sunspots could easily be explained away by the gaps in the chronological record. However, Maunder’s research was revived by Dr. Jack Eddy in the 1970′s, who also combed through Chinese records of naked eye sunspot observations. Today, the existence of the Maunder Minimum remains hotly contested, as does the Sun’s role and measure of effect in climate change.

Of course, today it is tempting and sometimes even fashionable to link the solar cycle to everything from fluctuations in the stock market to  the cycle of global conflict over resources to the prevalence of bikinis on your local beach, and the list of dubious links could provide headlines for your favorite search engine for years to come. But Hershel was in fact finally vindicated; in 2003, Israeli scientists proved that the link between wheat prices and the solar cycle in the 17th century was real. Similar assertions for top vintage wine years beg for a similar study. Wherever you stand on the global warming issue, few can deny that the shenanigans of our Sun  are tied up in the cosmic riddle.

The author ends on an interesting coda; in 2004, large gamma-ray burst tore through our solar system two days after Christmas.  This was powerful enough to effect our upper atmosphere for several hours, and was even recorded reflecting off of our own Moon! The source; a magnetar, a bizarre sort of pulsar just recently identified, about 50,000 light years distant. This event shows the emerging realization that not only are we at the mercy of our local Sun’s whim, but that there are much meaner beasties out there that can and do reach out and touch us. We owe the beginnings of this understanding to Carrington and his ilk, who proved, often amid controversy, that we are not immune or aloof from our cosmic environs. Read The Sun Kings and marvel at this largely unknown but fascinating chapter in astronomical history!