Who discovered Dione the moon of Saturn?
Dione was discovered by Italian astronomer Giovanni Domenico Cassini on the 30th of March 1684. He used a large aerial telescope set up on the grounds of the Paris Observatory.
Questions about Dione (moon)
Short answers, pulled from the story.
How big is Dione compared to other moons in the Solar System?
Dione has a mean diameter of 1,123 km, making it the 15th largest moon in the Solar System and the fourth-largest moon of Saturn. It is more massive than all known moons smaller than itself combined.
Does Dione have an atmosphere?
Dione has an exosphere rather than a true atmosphere. On the 7th of April 2010, the Cassini spacecraft detected molecular oxygen ions around Dione at a density of 0.01 to 0.09 ions per cubic centimeter, far too thin to qualify as an atmosphere in the conventional sense.
Does Dione have a subsurface ocean?
Scientific models based on Cassini data suggest Dione may have a global subsurface liquid salt water ocean beneath its icy shell. The evidence comes from the way the crust sags by about 0.5 km beneath the mountain ridge Janiculum Dorsa, which is most easily explained by tidal flexing from a liquid layer below.
What are the wispy features on Dione?
The features photographed by Voyager 1 in 1980 as wispy markings are actually towering ice cliffs formed by tectonic fractures. A Cassini flyby on the 13th of December 2004 revealed they are not ice deposits but chasmata, steep-sided canyons with cliff faces several hundred metres high.
What is Dione's relationship to Enceladus?
Dione and Enceladus are in a 1:2 mean-motion orbital resonance: Dione completes one orbit of Saturn for every two completed by Enceladus. This resonance maintains the orbital eccentricity in Enceladus that drives its internal heating and its cryovolcanic geyser-like jets.