This is posted in astronomy because it is assumed that at some point in the past the heavenly twins are derived from a real phenomenon rather than the dubious source of pre-Jewish and pre-Christian religion, as evidenced by the fact they had developed into protective deities rather than their subjective origin as destructive features of the natural world. J Rendell Harris, in 'The cult of the heavenly twins', written from the angle of an inquisitive theologian (Contemporary Review 95, 1909), a paper I came across when flicking through the archive of the late Janek Pietron, concerns the Dioscuri. The cult of the heavenly twins, progeny of Zeus, caster of thunderbolts, manifests itself in a plethora of names – such as Romulus and Remus, or Castor and Pollux. In various cultures around the world twins are associated with thunder or are described as the children of thunder – or the children of lightning. The same idea appears to be manifest in some place names found in ancient Palestine. We are all familiar with the Biblical tale of the defeat of Sisera which involved a character known as Barak = lightning, or the Islamic legend of the prophet riding into the heavens on a like named 'lightning horse' known as Borak. Well, Sennacherib, in his invasion of Judah records a town, Bannai Baraq (bana-ai-bar-qa) – which means lightning in the plural. Ibn-Abraq or Ibraq, 4 miles east of Jaffa, has the meaning 'son of lightning' in what would have been the tribal territory of Dan (supposedly one of the sea peoples with an Aegean origin). Harris goes on to connect this idea with the appearance of Yahweh and two angles under a sacred oak tree at Mamre, or various other incidents in folklore or holy writ.
The classical city of Barca in Cyrenaica (Libya) is derived from Barcas, a Punic or Levantine word which suggests that Barcelona in Spain may also have a Punic or Semitic origin. In contrast, some people see a link with aber and therefore a Celtic origin – so it is all a matter of opinion. However, Harris notes that Barcelona is recorded as Barqes in a Syriac list of the Nicene Council. The Dioscuri developed into protective deities. For example, near Jaffa there is a dangerous reef. They are also associated with other hazards such as rapids and falls on fast flowing rivers, lighthouse locations (lighthouses are constructed near hazards), dangerous tides and sandbanks, and rocks just below the surface. It therefore seems that the Dioscuri came to have a particular connection with the sea, rivers, and shipping – therefore the protective deities of mariners.