Chasma, which approximately follows a great circle with a pole near Odysseus' center, had been hypothesized to have formed as a result of the Odysseus impact. However, a study based on high resolution Cassini images indicated that this is unlikely—the crater counts inside Odysseus appear to be lower than in Ithaca Chasma, indicating that the latter is older than the former. References External links Astronomy Picture of the Day for 9 September 2007 Impact craters on Saturn's moons Surface features of Tethys (moon)