Because There are millions of craters on both these silly little chickens
IO is an active volcanic moon, and any craters are swamped with volcanic lava.Europa is an "ice" moon and any impact is swamped with melted water, which later refreezes.
Io Europa Ganymede Callisto
From Brightest to Dimmest: Ganymede Io Europa Callisto Use JPL's HORIZONS web ephemeris to look up apparent magnitudes of jovian satellites.
Io, Europa, Ganymede and Callisto are the four satellites that orbit Jupiter.
The four biggest satellites of Jupiter are Ganymede, Callisto, Io, and Europa. Ganymede is the largest moon in the solar system and is even bigger than the planet Mercury. These four moons are known as the Galilean moons, named after Galileo Galilei who discovered them in 1610.
IO is an active volcanic moon, and any craters are swamped with volcanic lava.Europa is an "ice" moon and any impact is swamped with melted water, which later refreezes.
it is ganyme and callisto
Ganymede is the biggest moon in the solar system.
going by the magnitude scale, Callisto's the brightest. Io 5.5 Europa 5.7 Ganymede 5.1 Callisto 6.1
Jupiter itself does not have a solid surface like terrestrial planets, so it doesn't feature traditional craters. However, its moons, such as the Galilean moons (Io, Europa, Ganymede, and Callisto), do have craters. The diameter of craters on these moons can vary widely, with some being just a few kilometers across, while others, like the largest craters on Callisto, can exceed 200 kilometers.
The neighboring moons of Callisto are Ganymede, Europa, and Ia.
Io Europa Ganymede Callisto
From Brightest to Dimmest: Ganymede Io Europa Callisto Use JPL's HORIZONS web ephemeris to look up apparent magnitudes of jovian satellites.
JUPITER
Orbiting planet Jupiter
Io, Europa, Ganymede and Callisto are the four satellites that orbit Jupiter.
Satelites of Jupiter