What is are the “Big Seven” Moons?
The “Big Seven” refers to the largest moons in the solar system, one of which is even larger than the planet Mercury. The Big Seven are larger than all other moons in the solar system by a significant margin. They are, in descending order of size: Ganymede (Jupiter), Titan (Saturn), Callisto (Jupiter), Io (Jupiter), Luna (Earth), Europa (Jupiter), and Triton (Neptune). They range in diameter from 2707 km to 5262 km. The eighth-largest moon in the solar system is Titania, Uranus’ largest moon, with a diameter of 1578 km. The Big Seven moons are also among the solar system’s most interesting moons, from the volcanically active Io, which looks like a pizza covered with sulfur, to Triton, which is believed to be a captured Kuiper belt object. Ganymede is so large it has its own magnetic field, while Titan is the only moon in the solar system with its own atmosphere. Europa is suspected to have large subsurface oceans with conditions that astronomers have long considered suitable for life.
