Top 7 largest moons in solar system captured by NASA

Ganymede, Jupiter's largest moon and the solar system's largest, is bigger than Mercury and the dwarf planet Pluto, with a diameter of 5,268 kilometers.

Titan, Saturn's largest moon and the second largest in our solar system, is unique for having a dense atmosphere, clouds, and surface liquids (methane and ethane), making it the only world besides Earth with such features. 

"Callisto" can refer to either Jupiter's second-largest moon, the third-largest in the solar system.

Io, Jupiter's innermost and most volcanically active moon, is a world of fire and lava, with hundreds of volcanoes erupting lava fountains and lakes of molten silicate lava,

The Moon is Earth's only natural satellite, orbiting at an average distance of about 238,855 miles (3,84,000 km), and it's tidally locked with Earth, meaning we always see the same side. 

Europa, a moon of Jupiter, is known for its icy surface, a potential subsurface ocean, and its potential for harboring life, making it a fascinating target for astrobiology. 

Triton, Neptune's largest moon, is a unique, icy world with a retrograde orbit (opposite to Neptune's rotation), and is thought to be a captured Kuiper Belt Object, potentially harboring a subsurface ocean. 

Credit: NASA