Phosphorescent wheels

Every now and then KNMI receives questions that cannot be answered adequately. Recently our attention was drawn again to a mysterious phenomenon: 'marine phosphorescent wheels'. These still unexplained phenomena are reported at sea for at least hundred years. 'Marine phosphorescent wheels' or 'oceanic light wheels' are luminous phenomena that are observed on ships especially in the Indian Ocean, Persian Gulf and the South China Sea. A lot has been written on this subject and many possible causes have surfaced, ranging from biological to seismic sources and possible connections to UFO theories and crop circles.

'Marine phosphorescent wheels' come in many appearances, often together with 'luminous parallel bands' or 'luminous rotating spokes'. Sometimes one, sometimes multiple wheels, rotating clockwise or counter clockwise, with a diameter between 3 and 200 metres, sometimes virtually stretching out to the horizon. At times the spectacle appeared to be under water, sometimes it seemed to be above the surface. Also in this context, 'under water rising and at the surface exploding balls of light' and 'submarine light rays' were observed sometimes together with the 'wheels'. Altogether, a wide-ranging, but very intriguing phenomenon.

To sketch a picture of how a 'phosphorescent wheel' may look, an observation of such an event, reported by the Dutch tanker 'Dione' on 5 November 1978, is given below. This report was published before in the Nautisch Technisch Tijdschrift/De Zee (nr. 4 - 1979), but is detailed to such an extent that it offers a good impression of one of the appearances of such an 'object'. The 'Dione' is one of the 45 Dutch reports of 'phosphorescent wheels' that were received at KNMI since 1910. It is remarkable, that no reports of 'phosphorescent wheels' were received - not even in other countries - from the time that only sailing ships roamed the seas. All reports came from motorized ships. Although bioluminescence (that's what it is all about) was also reported in the age of sail (milky seas and noctiluca scintillans), there was never a report from any sailor of such a dramatic event.

Spokes and wheels rotated approximately one meter above the water, and there where a spoke moved, the sea lightened strongly, about as far outward as the outer wheels. Behind the ship and next to the ship's stern, where the ship lights caused the spokes and wheel to be less, though still clear and recognizable visible, the lighting of the sea was less visible.

The width of the wheels was approximately 1.5-2m, narrower near the centre, but increasingly wider further outward. The spokes, or beams, were cone shaped, pointing at the ship, with the wider part of 2-2.5m outward and curved with a convex shape in the direction of the rotation. The colour of the lighting of the sea was not bright green like one often observes in the Persian Gulf, but fainter white-yellowish; both the wheels and the spokes showed the same colour. The lighting of the sea was visible in patches, nearly circular areas with a diameter of 0.5-1m. The wheels' circles were clearly visible abeam to approximately two ship lengths and forward to about half a ship length (length of ms 'Dione' is 244m).

As mentioned before, concurrently with the large wheel, more, but smaller wheels were clearly visible, with and without spokes (see Figure 1). They were still good visible while the greater wheel was disappearing. Looking at a wheel abeam on portside, it struck me that it didn't have any spokes, and that increasingly growing circles were formed from a certain point, the same that one notices when one throws a stone in the water. There were never more than 3 or 4 circles visible at once and they disappeared without notice. Slowly the wheels disappeared, the large one first, followed by the smaller ones.

Further specifications:

There is some relation between all phosphorescent wheel reports. Their geographical position is usual in the northerly coastal waters of the Indian Ocean and in the South China Sea, especially at water depths of less than 100 fathoms (about 200m), see Figure 2.

Figure 2. Locations of Dutch phosphorescent wheel reports

Vice-admiral G.F. Tydeman described the phenomenon (1911) as a combination of phosphorescent plankton, sea waves and the bow wave of the ship. Later (1921) he expanded his theory after an observation of the 'phosphorescent wheel' above the water. Tydeman explained this by assuming that the waves worked as a kind of lens, projecting the plankton's radiated light on a thin hazy layer, directly above the water. Later G. Verploegh elaborated this theory some more (1958).

The German Kalle described (1960) the connection between 'phosphorescent wheels' and 'luminous balls' - another rarely observed phenomenon. Luminous balls are described as 'balls of luminous water, rising under water and apparently exploding near the surface, where they expand circularly'. Possibly these phenomena are again related to 'flashing underwater search lights'. Kalle associated these phenomena with shock waves, caused by seaquakes. In deep water, Kalle explained, shock waves would cause the 'rising luminous ball' effect. In shallow water however, reflection of the shock wave between the sea-floor and the sea surface would cause a complicated pattern, similar to the 'phosphorescent wheel'. The Moiré-effect could underpin this explanation. The Moiré-effect is the name of an optical phenomenon, in which two independent grids move on top of each other and display more or less random patterns. Otto however, questions Kalle's hypothesis (1979). He notices that the 'luminous ball' observations are nearly exclusively from the route between Socotra and Sri Lanka and hardly from the Bay of Bengal or more to the east, while contrarily, most 'phosphorescent wheels' have been observed more easterly. Also the described shock wave mechanism still raises some questions. Above all, a correlation between the optical phenomena and seaquakes has never been demonstrated. The observations of 'luminous balls' and 'phosphorescent wheels' overlap the seismic active areas only partially.

Verploegh defended his elaborated Tydeman theory (1968). He particularly explained the perspective distortion, so often noticed by the observers of 'phosphorescent wheels' (bended spokes, flashing lights), as being caused by the lens effect of the waves.

Through the years the magazine The Marine Observer often reported on 'phosphorescent wheels'. Herring and Horsman, authorities on this matter, frequently gave their expert opinion. In an interesting article (1985) they discuss some possible causes, under which Staples (1966) suggested that electro-luminescence would be the cause. A shock wave would be able to generate light in oxygen bubbles that are produced during daytime, under the influence of sunlight, by photosynthesis in phytoplankton. Under special circumstances these shock waves and cavitations would lead to the same results. Herring and Horsman however, argue that it seems unlikely that these oxygen bubbles stay intact until the night (the time when the optical phenomena are being observed), and no photosynthesis occurs anymore. They think that the light is caused by bioluminescence, produced by small luminous organisms that live in the water. Especially Dinoflagellates, a group of single-celled algae, containing the Noctiluca scintillans, qualify for this. Another problem is the explanation of the remarkable patterns. A Russian writer Tarasov (1956) tried to explain them as being rotating movements in the water, while Leslie and Adamski (1953) considered them being signs of extraterrestrial visits by UFO's. Hilder (1962) interpreted the patterns as being a magnetic phenomenon, caused by a combination of local variations in the geomagnetic field and the effects of the steel and iron of the ships. The latter coincides at least with the fact that no observations are known from the era of wooden ships. It does not, however, explain the patterns (bands and wheels).

Resently Herring and Widder (2001) examined the 'phosphorescent wheels'. The writers do think in the direction of plankton near the sea surface that is activated by vibrations, caused by ships' engines or seismic activities, but still cannot find a conclusive explanation.

All in all there are several explanations from different corners, but no convincing explanation for the complete phenomenon. It seems clear that it is a form of bioluminescence. Especially Coccolithophores and Dinoflagellates are in the picture. The first group, the Coccolithophores, is a type of algae that appears all over the world (except the polar regions) and is visible from space as well in the appearance of 'milky seas'. These areas of bloom overlap the areas where 'phosphorescent wheels' are observed.

More observations

Herring, P.J. and Horsman, P. (1985). Phosphorescent Wheels: Fact or Fiction? The Marine Observer, 194-201.

Remarkable luminous phenomena in nature. A catalog of geophysical anomalies. Verzameld door William R. Corliss. The Sourcebook Project, 2001. HC, 419pp.

See also

 

  13 October, 2010 11:22