William Herschell's Observations about Sunspots and the Inhabitants of the Sun.

 Italian illustrator and printmaker, Leopoldo Galluzzo, for his book Altre scoverte fatte nella luna dal Sigr. Herschel (Other discoveries made ​​on the moon from Mr. Herschel).

The correlation between solar-activity and weather patterns across the world ought to be so self-evident to us, that the sun drives the weather, that an abundance of ‘the sun’ makes hot weather and that when the sun is occluded by clouds or the land less exposed during the winter seasons, then we get colder weather, and likewise it ought to be obvious that the strength of solar activity and the nature and strength of its radiations, will affect the weather and climate on all the bodies of the solar-system. 

Solar-activity and the sun-earth magnetic relationship for example has been implicated by some meteorologists, such as Piers Corbyn, as being the primary driver of Earth climate, though at present there is a contrary viewpoint which seems to predominate that it is human activity which is driving the climate. 

Historical cold periods such as the Little Ice-Age was also accompanied by the Maunder which was a sustained period of hundreds of years which featured very low sunspot numbers and thus low magnetic volatility of the sun. With this in mind, the present sunspot cycle, cycle 25, has been signalled by a lower-than-average number of sunspots and is projected to form the first stage of a sustained Grand Solar Minimum. 

If this is indeed the case, then it may well be that the solution to the present problem of rising temperatures due to Climate Change, may already be in hand and is already being managed in advance by our wise and benevolent star.

So, although we’ve established that the sun has a regular and observable cycle of activity we haven’t yet established what a sunspot is and this will lead to a very interesting digression featuring perhaps the man who has done most to establish the astronomical sciences William Hershel and some of his very serious misunderstandings which we as a modern audience may be tempted to be amused by. 

A sunspot is an area on the surface of the sun which can be observed on the surface of the sun which appears darker than the rest of the surface. They are caused by concentrations of magnetic flux which prevent the transference of heat from the core and thus are significantly cooler than the surrounding area and these areas build up with magnetic flux, potentially becoming larger until the magnetic field distortions can no longer be contained within the sun and are ejected along with billions of tonnes of plasma, these are known as coronal mass ejections.

Why we should care about sunspots, apart from their ability to form potentially destructive coronal mass ejections which may impact on Earth’s telecommunication and electrical infrastructure, is that from the earliest times of their observation they have been linked to changes in the Earth’s climate and that makes the study of sunspots very interesting to meteorologists, which was my particularly area of study for my doctorate at Queen Mary College, although this area of research hasn’t yet received quite the standardisation and funding I would say, as a disinterested observer naturally, that it probably deserves.

Even today, the idea of using observation of the sun to predict future weather and climate patterns, is treat with, at best, polite indifference, while at worst, relegated to the crank sciences, just as it was when the great William Herschel himself, the discoverer of Uranus and infra-red radiation, advanced a similar hypothesis before the Royal Society of England, from observing past sunspot observations and finding that the absence of sunspots coincided with high-wheat prices by which we might infer that the harvest was poor due to a lack of rain. 

He was ridiculed at the time, and even now his ideas are still met with research papers strenuously seeking to deny the correlation, although it didn’t help that poor Herschel drew some highly erroneous conclusions about the nature of the sun, believing that the sun was ‘a cool, dark solid globe clothed in luxuriant vegetation and richly stored with inhabitants.'

Herschel became well known as an expert manufacturer of reflector telescopes selling over 60 in his lifetime and constructed for himself an 18.6 inch reflecting telescope, only slightly larger than the one we have here, but he also ground the mirror for an extraordinary forty foot telescope with an enormous 48 inch, or 1.25 primary meter, reflecting telescope which at the time was the largest scientific instrument to have ever been constructed and with this he examined and explored the deep skies and we can only imagine with what sense of wonder Hershel discovered and documented over two thousand deep-sky objects including many distant galaxies, star clusters and nebulae and all of the deep sky objects which are commonly visible with a telescope such as this one, were first discovered and documented by William Hershel. There is no way to understate his importance in the field of astronomy and spectroscopy. Although Herschel correctly surmised that the sun is the source of all life on Earth, and that all the stars in the sky are ‘similar bodies’ to our own sun, he made some very serious mistakes about the composition of the sun itself.

Investigating the appearance of a sunspot in 1779 which was so large as to be visible to the naked eye, though no doubt using filters, or a screen, he rejected the contemporary suggestions that sunspots were analogous to volcanoes since he calculated its size as somewhere near 50,000 kilometres and thought it unlikely that a volcano of such a size could exist, instead he drew a parallel between the presence of sunspots and the appearance of the great red spot on the surface of Jupiter which he likely observed and studied extensively on telescopes of his own construction, and correctly surmised that the red spot of Jupiter was some kind of atmospheric activity, although incorrectly surmised that equally the sunspots were atmospheric effects in the sun’s ‘atmosphere’ and the brightness of the sun was caused by fluids of a ‘shining brilliancy’ and he concludes that sunspots are actually holes in the ‘atmosphere’ of the sun and are glimpses of the ‘real solid body of the sun itself’. It is interesting in this respect to see how far science has come in two hundred years and how childlike we in the modern era can look back on some of the views held by these undeniably great men of the past and it makes one wonder what scientific opinions and theories which we hold now will one day be looked on as childlike musings which the less generous mind might scoff at and ridicule.

I’ll just read this extract transcribed from a talk he gave on the 18th December 1794 entitled ‘On the Nature and Construction of the Sun and fixed Stars’: and during the talk Hershel read out one of the entries from his diary of observations:

‘Sept. 28, 1794. There is a dark spot in the sun on the following side. It is certainly depressed below the shining atmosphere, and has shelving sides of shining matter, which rise up higher than the general surface, and are brightest at the top. The preceding shelving side is rendered almost invisible, by the overhanging of the preceding elevations.’

With the sunspot’s appearance as being ‘clearly depressed below the surface of the sun’ Hershel imagined a whole surface of the sun riven by plains and mountains, his primary question about the nature of sunspots was whether they represented mountains poking above the ‘lucid atmosphere’ of the sun as he called it, or openings of the atmosphere to show the surface below, sometimes he wasn’t sure : ‘‘I saw the spot lower than the shining matter of the sun, and an extended plane, also depressed, with shelving sides rising up to the level, I also found that the sun was convex..”

This impression he drew through high magnification of the sunspots and must have observed the lines of magnetic flux working through the sun’s surface which we can observe here,” he pressed a button on his remote control again and a large image of a close-up sun-spot appeared, “and mistaken them for mountains or chasms of various kinds. you see how it might have struck Hershel as something either sloping down to a black surface, the lines of magnetic flux appearing, perhaps understandably, to Hershel’s eyes as gradient leading down, or as something like a mountain, rising up above what he thought was the atmosphere of the sun.

His reasoning that the sun was solid, in addition to his erroneous belief that the darkness and apparent irregular contours of sunspots reveals the dark surface of the sun beneath the ‘lucid’ that is ‘luminous’ atmosphere, was based on the evident fact of the strength of its gravity which he attributed to a ‘great solidity’ but also that if the sun were solid then it would be rather more like other observed bodies of the solar system at that time which were also all assumed to be solid.

With an amusing irony to the modern-reader, we see that he almost stumbled on something like a correct explanation, or at least much more correct, for the presence of sunspots, yet in its vicinity does an about turn and dismisses it all too quickly. It’s almost reassuring to see that these great figures from the past who exist in an exalted timeless state of pre-eminence in anything we endeavour in the realm of the astronomical sciences, were prone to the greatest and gravest of errors, which in most cases, history seems to have been kind enough not to let-on:

‘How very ill would this observation agree with the ideas of solid bodies bobbing up and down in a fiery liquid? with the smoke of volcanoes, or scum upon an ocean? And how easily it is explained upon our foregoing theory.’

Though I hesitate to tempt the wrath of the vengeful and potentially destructive power of the sunspots’ magnetic flux and provoke a cataclysmic coronal mass ejection by daring to refer to the sunspots as ‘scum’, his terminology was nevertheless an apt analogy, much nearer the mark than talk of mountains and plains with sloping sides in any case.

I’d just like to finish on hopeful note for the future of energy production. The sun of course relies on nuclear fusion of hydrogen as a source of its power and we on Earth are presently trying to emulate this process. 35 countries are currently working on the ITER project based in the rugged mountains of Provence in the South of France which was the fruit from discussions between Mikhail Gorbachev and Ronald Regan to develop nuclear fusion into a feasible and effective form of clean and safe energy production for the future,” he pressed a button on a small hand-held Bluetooth remote-control and the image on the screen behind him which had been of the construction site of ITER in the South of France changed to a TOKAMAK Torus fusion reactor.

“Already in China, the Tokamak has set a new record for sustaining a temperature of 70 million degrees Celsius for 17 minutes, this temperature is already 4 times higher than the core of the sun. Isotopes of hydrogen are super-heated using lasers to the point at which they fuse to form helium, which is pretty much what takes place inside the sun, except for the lasers I suppose but the laser aspect is provided by the extreme heat and pressure already inherent in the sun, the plasma is then contained by an artificial poloidal and toroidal magnetic field, again, another element present in the sun. The hope is that all of these elements will amalgam: the fused hydrogen, the extreme temperature and the magnetic fields, to recreate the sun itself and create a laboratory sun which will be able to provide near limitless clean and safe energy. Whether it works out that way remains to be seen, and we have to remember that the sun is very particular environment and that trying to recreate and harness such a cosmic force on Earth may not be quite as simple as throwing all the right ingredients into a torus reactor, turning on the gas and expecting a nice piping hot fresh sun to order. But if it works, then all of our energy difficulties will be solved once and for all and with that, almost all of the other problems which have plagued humanity for so long. I’ll leave you with that hopeful, thought, although of course, hope isn’t a strictly scientific term.