Stories from Mimas

Mimas, the smallest and innermost of Saturn’s moons, was discovered in 1789 by the British astronomer William Herschel, but remained little more than a point in the sky, visible only by telescope, until imaged by the Voyager 1 and 2 space probes in 1980/81. When planetary scientists received the first detailed images of this new world, they honoured its British discoverer by assigning its chasms and craters names from a late medieval reworking of Arthurian myths and legends, Thomas Malory's Le Morte d’Arthur (c. 1470). 


Saturn’s moon Mimas takes its names from people and places in Arthurian myth and legend. NASA ID: PIA12570.

Arthur and Merlin

The craters Arthur (64 km diameter, -35.4 N, 196.04 W) and Merlin (37 km diameter, -38.43 N, 219.01 W).

World of Arthurian Legend

Le Morte d’Arthur weaves together tales about the legendary British King Arthur, Queen Gwynevere, and their Knights of the Round Table. These stories are written onto Mimas's icy landscape through the 42 names assigned to its craters and chasms: craters taking their names from people, and chasmata (deep and steep-sided chasms) from places. King Arthur appears on Callisto's southern hemisphere, with his wise counselor Merlin a few degrees to the east. To their south lies a catena (crater chain) named Tintagil Catena, taking its name from the Cornish castle that had been associated with the legendary King Arthur since Geoffrey of Monmouth’s History of the Kings of Britain (1136). 

Launcelot and Gwynevere

Launcelot (diameter 30km, -9.46 N, 328.49 W) and Gwynevere (diameter 42km, -17.6 N, 323.7 W). Nearby is Mark (diameter 20.8km, -26.28 N, 308.32 W).

Dangerous Love

For all their tournaments, battles with giants, and dealings with sorcerers, the most dangerous thing to a knight is love. On Mimas, the dangerous love between Sir Launcelot and Queen Gwynevere is written in craters. Launcelot surpasses all other knights in 'worship and honoure', but his devotion to his king is matched by a forbidden love for his queen. This love inspires Launcelot in his questing and pursuit of noble deeds, but is also his greatest failing as a knight. When brought before the Holy Grail – the ultimate prize for a knight – it remains invisible to him because his knightly deeds were not done for God, but for Gwynevere. When, through Mordred's machinations, their adultery is exposed, Launcelot goes into exile, returning to England only after the death of Arthur. Finding Gwynevere in a nunnery, he too dedicates himself to God and becomes a priest. When Gwynevere passes, he lays her to rest besides Arthur, in atonement for the stain on his knightly character. Launcelot's tragedy is to be laid to rest away from his queen, at the castle ironically named Joyous Gard.

'Because that we undirstonde youre worthynesse, that thou art the noblest knyght lyvyng, and also we know well there can no lady have thy love but one, and that is Quene Gwenyvere'.

Thomas Malory, Le Morte d'Arthur (c.1470)

Tristram and Iseult

Tristram (diameter 20km, -52.32 N, 26 W) and Iseult (diameter 21km, -47.24 N, 33.78 W). 

Another unhappy romance written in craters is the tragic tale of Tristram and Iseult. Sir Tristram falls for Iseult when she tends to wounds he received while questing in Ireland. When he returns lovestruck to Tintagil castle, he regales his fellow knights with tales of her charm and skill. Unluckily for Tristram, these tales impress King Mark so much that he sends his knight back to Ireland to ask for her hand in marriage on his behalf. Bitterly, Tristram escorts Iseult back to Cornwall. On their way, however, the couple unwittingly drink a love potion meant to bind Iseult to King Mark. Their tragic love is sealed. Iseult and Mark are married, but she and Tristram remain lovers. Eventually, Mark catches them in the act, and banishes Tristram from his court. Fate is cruel, and Tristram marries another woman by the name of Iseult, but, pining for her namesake, never consummates the marriage.

Then they lowghe and made good chere, and eyther dranke to other frely, and they thought never drynke that ever they dranke so swete nother so good to them. But by that drynke was in their bodyes, they loved aythir other so well that never hir love departed, for well nother for woo. And thus hit happed fyrst, the love betwyxte Sir Trystrames and La Beale Isode, the whyche love never departed dayes of their lyff.

Thomas Malory, Le Morte d'Arthur (c.1470)

A view of Mimas

Mimas is one of the most heavily cratered worlds in our solar system. NASA ID: PIA17213.

Mimas is heavily cratered, and when the rims of these craters overlap they are assigned the names of lovers in Arthurian literature. In Le Morte d'Arthur, these unhappy romances are tragic betrayals of the knights' honour, faith, and duty, and it is their fates to be separated from their loves. On Mimas, however, it is their kings and husbands, Arthur and Mark, who are distant. Their craters are located, in both cases, nearly a hemisphere away.


Gawain (27km diameter, -58.54 N, 261.08 W). 

Knights and Lions

The crater Gawain takes its name from the storied hero Gawain, a Knight of the Round Table and King Arthur's nephew. Gawain was the hero of many stories in the Middle Ages. In one poem, he is challenged at a Christmas feast to swing an axe at a remarkable knight, green from head to toe. Gawain swings his axe, but the strange green knight is remarkably unfazed at having his head separated from his shoulders, and Gawain must wait with some trepidation a whole year until the green knight comes to return the blow. In another popular story, a disguised Gawain duels Ywain, another of Arthur’s knights, to settle a property dispute between two sisters. In battle, they recognise each other’s strength, cast off their disguises and ask wise King Arthur to settle the dispute instead.

The story of Ywain and Gawain originated in the French Ywain, Le Chevalier au Lion (Ywain, The Knight of the Lion) (c. 1180), by Chretien de Troyes, but was translated into English, as Ywain and Gawain, and from English into Icelandic, as Ívens saga. This story is an example of the legend of the lion-knight, a story of quest and adventure popular throughout the Middle Ages. It tells of a hero – sometimes a king, sometimes a knight – who rescues a lion from a dragon, the lion following him thereafter and becoming his loyal companion.

Valþjófsstaður door

The Valþjólfsstaður door (Þjms. 11009/1930-425). The National Museum of Iceland.

Valþjófsstaður door postage stamp

The Valþjólfsstaður door was for a long time on display at the Royal Museum of Northern Antiquities in Copenhagen (now the National Museum of Denmark), but was returned to Iceland in 1930 to mark the 1000-year anniversary of the Icelandic parliament. This postage stamp commemorates the 100-year anniversary of the National Museum of Iceland, where the door is now on display.

A version of this story is depicted on the Valþjólfsstaður door, carved in c. 1200 for a church in eastern Iceland. Scenes on the door's bottom half show an armoured knight on horseback rescuing the lion from the dragon, the grateful lion trailing behind him, and, finally, the lion lying devotedly on his master’s grave. Viewers may have identified this knight as Arthur's Ywain, while others may have seen the legendary Dietrich, a lion-knight whose story was told in the Icelandic Þiðreks saga af Bern.