Stories from Iapetus

Iapetus, Saturn’s third largest moon, is a world of contrast. Its most distinctive characteristic is its two-tone colouration, with a leading dark hemisphere followed by a trailing light hemisphere. This world is composed mostly of ice, with rocky material accounting for only around 20% of its makeup. Its two-tone colouration is probably the result of the sublimation (evaporation) of its surface ice, leaving behind a thin layer of darker dust and gravel perhaps only a few centimetres thick.  


Saturn’s moon Iapetus, notable for its striking colour dualism. NASA ID: PIA08384.

A world of contrast

Iapetus’s 70 place-names distinguish lighter areas from dark, and have been adapted from Le Chanson de Roland (The Song of Roland). This epic poem (chanson de geste) is the earliest surviving major work of French literature, preserved in a manuscript from England dated c. 1125. The poem tells of a battle between Charlemagne's armies and the Muslim king of Spain leading to the death of Roland, one of Charlemagne's lords. To match this world’s distinctive colour dualism, the IAU assigns ‘French’ (Frankish) names to craters in bright areas, and ‘Saracen’ (Muslim) names to craters in dark areas.

Iapetus Voyager mountains

The Voyager mountains on Saturn's moon Iapetus, demonstrating the world's distinctive colour dualism. NASA/JPL/Space Science Institute.

Turgis on Saturn's moon Mimas

Turgis (580 km diameter, 16.9 N, 28.4 W).

The Battle at Roncevaux Pass

The two large landmasses on Iapetus’s bright hemisphere take their names from the poem’s two main locations: the northern part called Roncevaux Terra (1284 km diameter, 37 N, 239.5 W), the mountain pass where the ambush on Charlemagne’s army took place; and the southern part called Saragossa Terra (2300 km diameter, -45 N, 180 W), the kingdom of the Muslim King Marsilion. 

Among the craters on Iapetus’s dark leading hemisphere are the huge and steep sided depressions Turgis and Abisme (767.74 km diameter, 37.53 N, 92.92 W). The rim surrounding Turgis is around 15 km high, casting a deep shadow on the plain below. These craters take their names from the Muslim baron Turgis of Turtelose (Tortosa), and the mighty warrior Abisme.

Marsilion and Bramimond

The craters Marsilion (136 km diameter, 39.2 N, 176.1 W) Bramimond (200 km diameter, 38 N, 178 W), on the edge of Iapetus's Saragossa Terra.

King Marsilion lends his name to crater on the edge of Saragossa Terra, within the larger crater Bramimond. When Marsilion loses his right hand in battle with Roland, Marsilion's Queen, Bramimond, curses Charlemagne, and becomes disillusioned with her Muslim religion. When Charlemagne destroys Marsilion’s armies and captures Bramimond, he spares the Queen on the condition that she converts to Christianity. She does so, and is baptised ‘Juliana’. 

Among the craters on Iapetus's lighter trailing hemisphere are smaller Roland (144 km diameter, 73.3 N, 25.2 W), Charlemagne, and Ganelon (230 km diameter, -44.3 N, 19.8 W). Ganelon was a Frankish knight and stepfather to Roland who is sent as envoy to King Marsilion. Ganelon resents Roland’s popularity among the Franks, however, and tells Marsilion where to ambush them, betraying Roland to his death.

This world of contrast draws its names from a western medieval poem about a battle between two opposing forces, twinning the moon’s colour dualism with the racialised distinction between European Christians and their monstered ‘Saracen’ adversaries. This is a problem. Le Chanson de Roland uses blackness symbolically as a means to align Islam with darkness and demonise Charlemagne's enemies. Elsewhere in western medieval literature, black Muslims who convert to Christianity sometimes undergo a miraculous change in skin colour, becoming white on baptism, representing their passage from spiritual darkness into light. The terms in which this medieval poem describes skin colour are fraught with pejorative associations. A medieval poem used colour to oppose 'enlightened' Christians and the wayward followers of a religion in 'shadow', and its Eurocentric biases, racism, and Islamophobia persist in the deep craters of Saturn's smallest moon.

Ogier crater

Ogier (100 km diameter, 42.5 N, 275.1 W) and Charlemagne (95 km diameter, 55 N, 258.8 W).

Holger Danske can come in many ways

The large crater named Ogier takes its name from Ogier the Dane, the legendary knight who helped lead Charlemagne’s armies in battle. Ogier first appears in Le Chanson de Roland, but his exploits became the focus of their own series of French chansons de gestes. These stories were reworked and translated into other medieval languages, becoming popular in Iceland and Scandinavia through works such as Karlamagnús saga and Holger Danskes krønike. In Danish tradition, Ogier, known as Holger Danske, sleeps in Kronborg Castle, where an enormous statue of Holger rests in stony slumber until Denmark’s hour of need, when he will return to save the nation.

Ogier the Dane, good Count, is at their head;
Great troops are they, and he a warrior dread.

Le Chanson de Roland, c. 1050

In the nineteenth century, Holger Danske became a symbol of Danish national identity, when writers looked to history for examples of distinguished Danish heroes. B. S. Ingemann, one of Denmark’s most famous poets, wrote his epic poem Holger Danske in 1837. Ingemann drew extensively on medieval imagery, and was presented on his 70th birthday with a golden horn decorated with images of Holger Danske, the Danish Bishop Absalon (c. 1128–1201), and Margaret I of Denmark (1353–1412).

Ingemann's golden horn

The Golden Horn presented to the poet B. S. Ingemann on his 70th birthday, 1859. Ogier, or Holger, is on the left. The Museum of National History at Frederiksborg Castle, B 1067.

De danske Kvinder overrækker Ingemann Guldhornet

Jørgen V. Sonne, 'De danske Kvinder overrækker Ingemann Guldhornet' / 'The Danish women present the Golden Horn to Ingemann', 1860. Oil on canvas, 42,5 x 36,5 cm. The Museum of National History at Frederiksborg Castle. Photo: Hans Petersen.

Jo, Holger Danske kan komme paa mange Maader, saa at der i alle Verdens Lande høres om Danmarks Styrke!

Yes, Ogier the Dane can come in many ways, so that all the world’s lands shall hear of Denmark’s strength!

Hans Christian Andersen, Holger Danske (1845)

In 1845, H. C. Andersen wrote his short story Holger Danske, a meditation on what it means to be a hero for Denmark. Andersen describes other Danes besides Holger who had made distinguished contributions to the arts and sciences, including the astronomer Tycho Brahe (1546–1601), author Ludvig Holberg (1684–1754), and sculptor Bertel Thorvaldsen (1770–1844). H. C. Andersen writes that ‘Holger Danske can come in many ways’, but he could little have imagined that Holger would one day return as a crater on one of Saturn’s distant moons.

Global, colour mosaic of Saturn's moon Iapetus, by NASA/JPL-Caltech/Space Science Institute/Lunar and Planetary Institute. NASA ID: PIA18436.