Penelope (crater)
Third-largest impact crater on Saturn's moon Tethys.
Penelope is the third-largest impact crater on Saturn's moon Tethys. Its shape is unusually elliptical, stretching about 180 kilometers along its shorter axis and 220 kilometers along its longer one. The crater sits near the equator, close to the center of Tethys’s trailing hemisphere, at coordinates 10.8°S, 249.2°W. It lies roughly opposite Odysseus, the largest crater on Tethys. The name comes from Queen Penelope of Greek myth, the wife of King Odysseus in Homer’s *Odyssey*, and was officially approved by the International Astronomical Union in 1983. Geologically, Penelope’s longest axis runs almost exactly north–south, deviating by only one degree. With an average diameter of about 207.5 kilometers, it is the fourth-largest known impact structure on Tethys. The western crater wall is bright, exposing fresh ice from the moon’s crust, while the eastern wall is much more degraded. Inside the basin lies a heavily degraded central peak ring roughly 50 kilometers across; its best-preserved sections are the northern and southeastern arcs. Several faults cut across Penelope, including one that crosses the basin floor but stops at the crater rim. The crater is deep and unrelaxed—meaning it hasn’t flattened out over time, unlike some other major impact craters on Tethys. Penelope and a nearby unrelaxed basin, Antinous, may form a province of such craters between roughly 120°E and 30°E. The surrounding region is dominated by heavily cratered terrain. East of Penelope, a network of roughly parallel narrow troughs cuts across an older, more degraded set of troughs. Areas to the east are especially rugged and densely cratered. Unusually, Penelope and most of Tethys’s other large impact craters are all concentrated on the trailing hemisphere, south of the equator.
Quick Facts
- Location
- Tethys
- Diameter
- 207.5 km
- Eponym
- Penelope
Facts from the source article.
Lore & Background
Penelope is a highly elliptical crater, with its shortest axis roughly 180 kilometers and its longest axis roughly 220 kilometers, aligned almost exactly north–south with a deviation of only 1°. Its western crater wall is bright, exposing fresh ice from Tethys's crust, while the eastern crater wall is comparatively much more degraded. Within the basin floor lies a heavily degraded central peak ring approximately 50 kilometers in diameter, with its northern and southeastern arcs being the best-preserved sections. Several faults cross Penelope, including a tectonic feature that crosses the basin floor but does not continue beyond the crater rim. The crater is rather deep and unrelaxed, having not been flattened out as with some of Tethys's other major impact craters. It and another nearby unrelaxed impact basin, Antinous, may represent a province of unrelaxed craters between ~120° E and ~30° E. The region is dominated by heavily cratered terrain; to the east is a network of roughly parallel narrow troughs cutting across older, more degraded troughs. Unusually, Penelope, alongside most of Tethys's other large impact craters, are all concentrated on Tethys's trailing hemisphere to the south of the equator.
Reader's Guide
Penelope is significant as the third-largest impact crater on Tethys and the fourth-largest known impact structure on the moon, with an average diameter of roughly 207.5 kilometers. Its unusual elliptical shape and north–south alignment distinguish it from more circular craters. The crater's unrelaxed state—meaning it has not been flattened by geological processes—contrasts with other major impact craters on Tethys, and together with Antinous it may define a province of unrelaxed craters. The bright western wall exposing fresh ice offers clues to the moon's subsurface composition. Its location near the equator on the trailing hemisphere, where most large craters are concentrated, provides context for understanding Tethys's impact history. The crater's name, approved by the IAU in 1983, links it to Greek mythology as the wife of Odysseus, whose namesake crater lies opposite Penelope on Tethys.
Did You Know?
- Its longest axis is aligned almost exactly north–south, deviating by only 1°.
- The crater's western wall is bright with fresh ice from Tethys's crust.
- Penelope is named after Queen Penelope, wife of Odysseus from Homer's Odyssey.
More in Moons of Saturn, Part 2 1-24
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