I won't miss the crop circles, what with cups and rings and sun-dogs Down, down, croppies lie down. So perhaps it's just as well that most of the obliging men with the planks and lengths of rope have been at work not in County Londonderry but safely within range of Stonehenge and Avebury stones. It was in those rolling chalklands that the curious antiquarian John Aubrey (seldom off horseback in the mid-17th century) was puzzled by green circles on the Wiltshire downs. "I presume they are generated from the breathing out of a fertile subterraneous vapour," he wrote in his notes for a book on the county, to which he initially gave the catchy title Hypomnemata antiquaria, which might be translated as Jottings. Anyway, Aubrey likened the circles to smoke rings: "Every tobacco-taker knowes that "tis no strange thing for a circle of smoke to be whiff'd out of the bowle of the pipe; but "tis donne by chance." Chance was a funny word to use - in a way, as it applied to smoke rings, an adumbration of chaos theory, since any individual particle of smoke goes off unpredictably, yet the whole cloud curls itself into a neat mobile torus. But by analogy, all Aubrey meant was that the production of grass circles was done by nature (that fictional creature), not by men with bits of planking. In any case, the circles that Aubrey was talking about were green rings on the grass, which we still call fairy rings. They are caused by fungi, and sometimes you can see the toadstools at it, growing in an ever-widening hoop on the grass. Any number of fungi produce the rings, from the delicious St George's mushroom to the murderous death-cap. More surprising, at first glance, are the concentric rings that appear in moss in Iceland and suchlike northerly wildernesses (ideal, perhaps, for fracking). There are plenty on Svalbard, but moss-circle hunters there are advised to go in pairs, with one to shoot the hungry polar bears that welcome the arrival of British tourists. They (the circles, not the bears, nor the tourists) are up to a yard across, but they are not made by very small men with matchsticks tied to their boots. The striking thing about these Arctic moss circles is their resemblance to the mysterious "cup and ring" markings on rocks. There are some of those marked on the Ordnance Survey map for Ilkley Moor, and there is a particularly fine specimen at Lochgilphead in Argyllshire. The poet and countryman Geoffrey Grigson speculated that these incised rings were Bronze Age representations of the Earth Goddess, though I must say the resemblance eludes me. They are certainly widespread, with some in Greece and plenty in Galicia, north-west Spain. As far as I know, no one has suggested that cup-and-ring rock scribings are of natural occurrence, but there are other circly phenomena that are simply astonishing. The first time I saw two suns at once, I did think that I had lost my reason. That was in Northumberland, above Otterburn. It was a fine day, for Northumberland; in other words, a little misty but not raining. Above the horizon hung the afternoon sun. A little to the right hung another one. It was in reality nothing but a sun-dog, or parhelion. To give it a name is almost to explain it. The cause, we are told, is refraction of light through ice-crystals. The effect is to produce copycat suns on either side of the real one, at 22 degrees" distance. "Dazzle mine eyes," exclaims Edward at the beginning of Henry VI, Part Three, "or do I see three suns?" I only saw one extra sun that time, but John Sell Cotman, the great watercolourist, sketched a parhelion that he observed in July 1815 above the Wash off the coast of Norfolk near Hunstanton. It was a fine display with a complete circle of light at 22 degrees, another at 46 degrees and a pair of false suns. When it's very cold, ice circles form on the surface of slow streams and lakes. You may find one big ice circle surrounded by a fleet of ice circlets, like a duck with ducklings. Or the little ice circles may each have a ridge of ice crystals encrusting its circumference like an ermine collar. Telegraph readers sent in wonderful photographs of some last time we had a hard winter. So perhaps it doesn't matter that the crop-circle artists are hanging up their trampling-boards. There are numberless patterns of circles in the world around us, day and night, from the nano to the mega, the sub-atomic to the hyper-galactic, and those are quite impressive enough.