Ganymede, Jupiter’s largest moon, is bigger than Mercury and Pluto, and likely has a vast underground saltwater ocean with more water than all of Earth’s surface
Image Credit: NASA
Titan
Titan, the second-largest moon in the solar system, is bigger than Mercury and just 2% smaller than Jupiter’s Ganymede. Its nitrogen-rich atmosphere has 50% more surface pressure than Earth’s.
Image Credit: NASA/ JPL-Caltech
Callisto
Callisto, Jupiter's second-largest moon and the third largest in the solar system, has the most heavily cratered surface of any known object.
Image Credit: NASA
Io
Io, just bigger than Earth’s Moon, is stretched by Jupiter and its moons, causing intense volcanoes and lava lakes visible from Earth.
Image Credit: NASA/JPL-Caltech/SwRI/MSSS
Earth's Moon
The Moon, Earth's only natural satellite, orbits at 384,399 km and takes 29.5 days to rotate and revolve—always showing the same face to Earth. Its gravity drives Earth's tides.