A small digression – the ancients blamed both Mars and Mercury for throwing stones.
The Latins blamed Mars on a Tuesday – dies Martis (the day of Mars, Martis L, Mardi Fr). And they blamed the dragon/demon Mercury on a Wednesday- called Mercredi (Fr), Mercoledi (It) or Miercoles (Sp). So where did the fatal stone actually come from?
Mythology does provide answers but that’s a long winding path because the surviving versions are fragmented, inconsistent and even contradictory. Here is a short version –
One day (about 11,000 years ago according to modern science) there was an enormous supernova explosion in the constellation of Vela, not very far away. So large that the white star-burst was visible in daylight. The remains of the Vela nebula can still be seen in our night sky, against the background of the even larger, earlier Gum nebula. The stupendous explosion of energy fragmented adjacent planets sending solid debris in all directions, including towards us. A terrestrial fragment of black-bodied comet-asteroid entered our solar system and was attracted at first by the gravitational pull of Uranus. Pulled apart by competing gravitational forces of the larger planets (the Sun and Jupiter), it split into twelve fragments which – in the mythological account – became the 12 Titans who later attacked Uranus and castrated him, throwing his testicles into the ocean (of space).
These two small spheres became the comet-planets Mercury and Venus, pulled into periodic elliptical orbit around the Sun on the inner end and distant Pluto on the outer end. Three times they made the circuit, each time hazardously threading their way through the gravitational maze of the solar system. Until on the fatal fourth pass Venus was attracted too close to Earth, and following along Mercury smashed hard into Mars. So hard that it left Mercury with a concave cleft on one side, and a convex bump on the other; and left Mars with a gigantic circular crater covering about a third of its northern hemisphere.
The immense energy of this impact ejected the terrestrial debris that now remains in the Asteroid Belt, and one particularly large piece – of iron – descended into fateful impact with Earth.
So it was Mars who threw the stone, but it was caused by the collision of Mercury, who in turn was led astray by Venus’ fatal attraction to Earth. But considering that nearly all known Mars meteorites are ordinary stone – whereas Mercury is ‘iron hearted’ – it seems most probable that the offending iron object was actually a piece of Mercury.
Indeed, according to Hesiod’s version, it was Mercury’s ‘charioteer’ who fell to earth in flames to be mourned in a ‘flood’ of tears. So it was probably Mercury who owned the great iron sword of Excalibur that was thrust through the side of the isle of man.
Remarkably, a plain English summary survives in the unlikely context of Geoffrey of Monmouth’s History of the Kings of Britain, from about 1150 AD. He was a Welsh cleric who translated from earlier Celtic sources, including this fairly plain account. ‘The planet Mercury changed its shield … and Mars called to Venus … and in its rage Mercury over-ran its course … Venus deserted its appointed circuits … the stars averted their gaze and altered their accustomed course … the Moon’s chariot ran amok … and the malice of the planet Saturn poured down like rain, killing mortal men as though with a sickle’. That account was presented, or later translated (via Latin), in the future tense as a ‘vision’ – which was just a standard Establishment device of the time for avoiding the fatal consequences of heresy.
All that and more detail was related elsewhere in the colourful images of folklore and mythology. The supernova starburst was recounted in Celtic lore as the gods watching (in daylight) as a pot of milk boiled over; while the Persian version (the Rubaiyat) was ‘the bloom of morning that flung the stone that put the stars to flight’. The Egyptians witnessed plainly that ‘the sky spat forth a stone’, while the Greeks said the gods laid a cosmic egg and threw out a ‘cuckoo stone’ from the nest. The errant stone was captured at first by Uranus – Ouranos, the ‘First Father’ of the Greek gods – whose gravitational pull split it into twelve ‘children’ – the Titans. They later assaulted their (grand)father, castrated him, and threw his balls into ‘the ocean’ – of space – where they became the periodic comets of Mercury and Venus.
These two comet-planets formed the archetype for a cast of adventurous ‘couples’ from Greek mythology – the Fair Maiden Aphrodite and her constant White Knight, Hermes; Theseus who followed Ariadne’s thread to slay the Minotaur; Perseus who slew the dreaded Gorgon to save fair Andromeda; Theseus (and Hades) who fought over Persephone; the vying warriors Apollo and Athena (or Artemis); culminating in the Homeric pairs of Menalaus and Helen, and Odysseus and Penelope.
These names were just labels for the forms and moods of the demi-god characters who were the dramatis personae of myth. Venus was alternatively the seductive fair maiden Aphrodite; or the vengeful warrior Athena; or on a really bad-hair day, the dreadful Medusa turning everything to stone. Likewise, Mercury, as the mood took him, was the worthy White Knight; or the pitiless warrior Apollo who rained his arrows on Homer’s Troy until the earth ran red with blood; or abject Odysseus who wended his way home to the bosom of Penelope, by the ‘fireside’ of the sun.
And it wasn’t just in Greek myth. The parallel twosomes, and parallel adventures, are also found in the Celtic Mabinogion (The Tale of Taliesin) featuring the gallant knight, Culwych and his fair maiden, Olwen – threatened at every turn by the flying, fire-breathing, hairy black boar Twrch Trwyth who cast down his stone litter of ‘piglets’ on hapless man.
Where the Greek versions were set in the eastern Mediterranean the corresponding Celtic stories were set in ancient Armorica (Brittany and Britain), peopled with unpronounceable names. Just as Greek Agamemnon (brother of Menelaus) gathered together Apollo, Achilles and Ajax and their kin in black-hulled ships in the Aegean ‘sea of goats’ to rescue Helen; so similarly Culwych (Arthur) of the Mabinogion gathered his Celtic clans to fight the ‘droppings’ of the dreaded black boar, Twrch Trwyth, and win the hand of the fair maiden Olwen. He gathered his kin of Caerdathal; and Ysperni son of Fflergant, king of Armorica; Gormant son Ricca son of Penhynev of Cornwall; and Dunard king of the north; and Paris king of France; the sons of Llwch Llwwynnyawg, from beyond the raging sea; Gwittart son of Oedd, king of Ireland; and Gwynnhyvar, mayor of Cornwall and Devon; and Brys, son of Bryssethach from the Hill of Black Fernbrake in north Britain.
Until the final prosaic parallel in the Grimm tale of Hansel & Grethel who journeyed three times to and fro across the ocean of the forest. Where Ariadne provided a golden guiding thread to navigate the maze, so Hansel & Grethel used a trail of white breadcrumbs (or pebbles) to find their path across the ocean. The dreaded Minotaur, of course, came ‘out of the depths’ – not of Earth but of space. On their final return, Hansel & Grethel encountered the red ginger-bread house of the ogre (Mars), where Hansel ‘ate the roof’ (Mercury collided with Mars leaving a massive scar on the ‘roof’ of its northern hemisphere). Until, ultimately, the errant pair escaped across the lake (of inner space) to live happily ever after near the ‘Golden Castle’ (the Sun) – just as Odysseus joined Penelope ‘by the fireside’ of home.
The actors of The Iliad, The Odyssey, The Aeneid and The Mabinogion were all Hollywood heroes, created by the storytellers of their day. The skilful raconteurs took an original real-world event – somewhat remote – and dramatised it with local names and places. Like a modern film script-writer, they added standard devices for dramatic effect and local popular appeal at the box office – a love interest, some gratuitous sex and violence, a car chase (or horse and chariot race in their case). They did their job so well that the story became the story, and the original reality was forgotten. Still every summer earnest English Dons escort equally earnest cultural tourists around the Homeric sites of the Aegean – which is a pleasant pastime, but it is romance, not reality.
Homer never even existed as a single person. In a marvellous recent analysis, Adam Nicholson has documented numerous annotated manuscripts of The Iliad dating back to the 10th C, perhaps as early as 150 AD, with allusions to sources pre-700 BC.  Clearly, the Iliad is a rendition assembled from many prior manuscripts, in turn, derived from centuries of oral tradition. It was the Iliad of Homer, not by Homer. It was the Ile-ode-of-Homeros, the epic story of the isle of man.
Over 300 years ago Isaac Newton observed that Odysseus wandered through our solar system, not around the islands of the Mediterranean. It was the ‘ode-essay’, the story of the journey. Leaving behind the destruction of Earth (Ilium) he re-encountered Mars now characterised as the Cyclops, a giant sleeping (inert) ogre with a single enormous eye (the circular impact crater on its northern hemisphere). The now-aged Odysseus (Mercury) was ‘hump-backed’ and stripped of his youthful flesh – through planetary collisions – and orbited homeward to join Penelope by the ‘fireside’ of the Sun.
As for Virgil’s Aeneid, it was not written until centuries later around 50 BC as a Roman version of events shamelessly plagiarised from Homer and Hesiod. Revered now as literature, but pure romance. Virgil had his hero, Aeneas, flee the fall of Troy and wander around the Mediterranean before settling in Italy to defeat the resident Latinians and establish Rome. All this was a fiction contrived to provide a link from Iulus son of Aeneas who was the son of Anchises and Aphrodite – sprung from the gods – to allow Augustus Caesar (and others later) to dubiously claim divine descent. The Aeneid is revered as literature, but it should be derided as plagiarism and propaganda.
The wonder is not that the ancients made all this stuff up, but that we believed it for so long. So where does this leave the site of Troy?
 Nicholson, Why Homer Matters