Unlike the strictly monogamous Earth, Jupiter was a staunch supporter of "polygamy," with a total of 63 moons.
And Callisto... was the second-largest moon orbiting Jupiter, as well as the third-largest moon in the Solar System. Its diameter was roughly the same as Mercury's, but its mass was only a third of Mercury's.
Callisto was tidally locked, always keeping the same face toward Jupiter. It consisted of almost equal amounts of rock and water and had an extremely thin atmosphere composed primarily of carbon dioxide.
Observations also suggested that a liquid-water system might exist more than 100 kilometers beneath Callisto's surface. It also had a highly active ionosphere.
Its main geological features included multi-ring structures, impact craters of various shapes, crater chains, cliffs, ridges, and sedimentary terrain. Its terrain was extraordinarily complex, but its geological structure was stable.
"They actually chose Callisto? True... for a womanizer like Jupiter, with wives and concubines everywhere, its moons are basically indistinguishable extras. And something without any distinguishing features is the hardest to predict.
"Also, this terrain... looks like their ground combat weapons are well suited to complex landscapes..." Nie Yun analyzed the situation as he studied Callisto's holographic projection, rubbing his chin.
The Asteroid Belt lay between Mars and Jupiter. Though they were neighboring planets, the distance between them was greater than the distance from Mars to the sun. Among the Solar System's major planets, the farther out they were, the greater the distances between neighbors.
Although Nie Yun's side was closer to Callisto, the Gemini Civilization's two ships had already been accelerating for nearly a month and were traveling faster. Both sides should reach Callisto at roughly the same time, preventing either side from laying traps in advance.
"No... there should be more to it! They've visited the Solar System several times