Eurotas Chasmata, Janiculum Dorsa, and Evander Crater
Walk with me down one of the Padua Chasmata and we'll pass through the craters Amastryus, Pagasus, and Tereus along the way. The International Astronomical Union (IAU) has recently given its blessing to a host of new names for features on Saturn's moon Dione, a formal (and late-arriving) indication that Cassini has improved enough on Voyager's maps of the moon that new names are required to describe its features.
Here's a map of Dione, assembled from a variety of sources by Steve Albers, with the feature names mapped onto it by Jason Perry. The IAU decreed long ago that Dione's features shall be named for people and places from the Aeneid of Virgil. Sorry it's not too legible at this resolution -- you need to download the full 1.3 MB version to read well.
NASA / JPL / SSI / mosaic by Steve Albers / map by Jason Perry
Feature names on Dione
On March 17, 2008, the International Astronomical Union approved a number of new names for features across Dione.
catena (singular), catenae (plural) - chain of craters
chasma, chasmata - a deep, elongated, steep-sided depression
dorsum, dorsa - ridge
fossa, fossae - long, narrow depression
Those are the features that can be found on Dione; the full list of planetary feature types is here. Clearly there is some level of subjectivity when it comes to deciding whether a feature has dramatic enough topography to be called a "chasma" or whether it's just a "fossa."
As of 1982, when the Voyager maps were drawn, only 25 craters and four chasmata had received names, and three bright streaks in Dione's leading hemisphere "wispy terrain" were tentatively lamed as "linea," a vague identifier meaning "a dark or bright elongate marking." Those three "linea" names have been dropped, now that better pictures are available to identify them for sure as chasma or fossae, two crater designations have shifted slightly, and 45 new feature names were approved. Here's the full list, with their origins.
River in the Apulian territory of Diomedes, now called the Ofanto.
A Lydian river said to carry gold dust after King Midas washed off his golden touch in its waters.
River of Sicily.
A town in Thessaly, Achilles' native region.
The Trojans' promised land in Italy.
One of the Seven Hills of Rome. Note: Descriptor term changed to plural (chasmata) and coordinates and size changed 3/17/2008.
Ancient town of Italy not far from Rome on the river Arno.
An old town in Campania.
Coastal town of Sicily where Aeneas found a safe harbor during a raging storm, and where Anchises died.
The river on which Sparta stood.
City in northern Italy founded by Antenor. Note: Changed from Paudua Linea 3/17/2008.
Hill across the Tiber river from Rome.
Town in Apulia (now Puglia, southern Italy) founded after the Trojan war by Diomedes.
One of the twelve chief cities of Etruria, situated on the river Clanis.
Town in Latium near Rome.
Town of Lucania in southern Italy, founded by Philoctetes.
A Punic (Phoenician) city in North Africa. Note: Name changed from Carthage Linea 3/17/2008.
King of Argos, one of the seven against Thebes, and the only one to return alive.
Hero of the Aeneid. The son of Anchises and Venus and a member of the royal family of Troy.
Mother of Lavinia (wife of Aeneas). Note: Name moved 3/17/2008 to a smaller, well-defined crater.
Nephew of Priam. He escaped the fall of Troy and reached Italy before Aeneas, where he founded Padua.
A famous boxer who had been defeated by Dares.
A nurse of Aeneas.
Daughter of Priam; she could fortell the future. Note: Name moved 3/17/2008 to a small, well-defined crater.
Brother of Tiburtus and twin brother of Coras.
Brother of Tiburtus and twin brother of Catillus. He was founder of Tibur and an ally of Turnus against Aeneas.
Daughter of Priam; first wife of Aeneas.
Tyrian princess who founded Carthage.
A Trojan defending Aeneas' camp against the Rutulian attack. He was killed by Turnus.
Also known as Rhea Silvia; Mother by Mars of Romulus and Remus, the founders of Rome.
Ancient hero, eponymous ancestor of the Italians.
Soldier of Aeneas.
Son of Mezentius, killed by Aeneas.
A soldier of Turnus, killed by Aeneas.
An Etruscan ally of Aeneas.
Pilot of Aeneas' fleet. Note: Defines 63 degrees longitude on Dione. This name was mistakenly applied to a larger crater (4.0S, 61.4W, 33 km), but was moved back to the longitude-defining crater (also a RAND control point crater) on Jan. 11, 2008.
He and his brother Romulus founded Rome.
A Trojan. He fought at the side of Aeneas during Troy's last night.
Mythical founder of Rome in 754 or 753 B.C., son of Mars by Ilia (Rhea Silvia).
Fabled ancestor of the Sabines.
Rutililan king; Aeneas' rival for hand of Lavinia.
A warrior maiden; ally of Turnus.
King of Sicily.
One of the Furies.
A Trojan, victim of Camilla.
A Trojan, comrade of Aeneas.
Sister and confidante of Dido.
Son of Aeneas by Creusa.
Etruscan chief, ally of Aeneas.
A Trojan warrior who took part in the defense of Aeneas' camp against the Rutulians.
A Rutulian, father of the twins Thymber and Larides.
Ancient king of the Laurentians.
Sicilian boxing champion.
Superhuman son of the goddess Feronia.
A Trojan companion of Aeneas, friend of Nisus.
A Trojan companion of Aeneas.
Son of Mercury by Carmentis, ally of Aeneas against the Latins, mythical king of Arcadia, founded and ruled Pallanteum, built on the future site of Rome.
A Rutulian who besieged Aeneas' camp.
A soldier of Turnus.
A Rutulian, member of Turnus' army, son of Daucus, twin brother of Thymber.
King of Latium, husband of Amata.
Soldier of Turnus, brother of Lucagus.
Soldier of Turnus, brother of Liger.
A Rutulian, charioteer of Turnus.
Etruscan king, ally of Turnus, father of Lausus.
Trojan companion of Aeneas, friend of Euryalus.
An Etruscan killed by Camilla.
Trojan defending Aeneas' camp against Rutulian attack.
Trojan defending Aeneas' camp against Rutulian attack.
Servant of Aeneas.
Son of Aeneas and Lavinia.
A Trojan, killed by Camilla.
A Rutulian, member of Turnus' army, son of Daucus, twin brother of Larides.
Brother of the twins Catillus and Coras, founder of Tibur to which he gave his name.
Keeper of the herds for Latinus, father of Silvia.
hile researching this entry I made the happy discovery that the Gazetteer has a news page -- this must have existed for a long time, but I hadn't noticed it until now. In addition to this news about Dione, there's some other significant stuff in the Saturn system. They have decided that a spot in Dilmin, northwest of the Shangri-La region in which Huygens landed, can now be identified as a crater, "Selk." And they approved back in September a number of names for small lakes near Titan's north pole.
Prometheus, Saturn, and the rings This photo (the blue image from a series taken for a red-green-blue composite) was taken by Cassini on April 13, 2007 and captures Prometheus in its orbit between the A ring on the left and the F ring on the right, a space now named the "Roche Division." All of the rings cross Saturn's disk, but because the F ring is mostly transparent, light from Saturn's disk shines through, making the F ring nearly impossible to see against it. To the left, the Encke Gap can be seen as a gap in the A ring through which light from Saturn's disk shines clearly. Credit: NASA / JPL / SSI
You might ask why they didn't give names to what are obviously much larger lakes on the same map. I don't know for sure, but I am guessing it is because it is not clear how many lakes those huge black spots represent. Depending on what lies in the still-unmapped area, we could be looking at two or three or five different lakes -- so naming them will have to wait for better maps.
Finally, they've officially renamed "Encke Division" to "Encke Gap" in order to make definitions more consistent (a usage I've been following for a while), and have named the division between the A and F rings (where Prometheus and Atlas orbit) the Roche Division. What's a division and what's a gap? According to this page, "Divisions are the separations between named rings, and gaps are the spaces within named rings. In general, divisions are large, gaps are small." And they've changed the spellings for a couple of the outer, irregular moons. Looks like I have a lot of editing to do on my Saturn pages!
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