SECOND. In terms of size, Titan occupies second place among the NATURAL satellites in our solar system.Titan is the largest moon of Saturn and the second-largest natural satellite in the Solar System.It is the only moon known to have a dense atmosphere, and the only known body in SPACE, other than Earth, where clear evidence of stable bodies of SURFACE liquid has been found.Titan's atmosphere is active and complex, and it is mainly composed of nitrogen (95 PERCENT) and methane (5 percent).Titan also has a presence of organic molecules that contain carbon and hydrogen, and that often include oxygen and other elements similar to what is found in Earth's atmosphere and that are essential for life. Jupiter's moon Ganymede is the largest satellite in the solar system.