* Size: Ganymede is significantly larger than Jupiter's other moons, making it inherently brighter due to its larger surface area reflecting sunlight.
* Reflectivity (Albedo): While Ganymede isn't the most reflective moon (Europa has a higher albedo), it's still a very bright object due to its size.
* Distance: Although Ganymede is farther from Jupiter than some of the other moons, its size and reflectivity more than compensate for the distance.
While other moons like Io and Europa might appear very bright at times, Ganymede's sheer size would ultimately make it appear the brightest from the surface of Jupiter.
