Question #21 – On March 25, 1655, Cristiaan Huygens discovered Saturn's largest moon, Titan. How large is Titan?
Titan is larger than our Moon. In fact, it is larger than the planet Mercury! The only moon in the solar system that is larger than Titan is Jupiter's moon, Ganymede. Titan has a diameter of about 3,200 miles.
Read more about Titan on this Wikipedia page.