Just as the planets became more and more icy the further from the sun, moons seem to be more and more icy the further from the planet they orbit. The nebula was colder in the vicinity of Saturn, than in the vicinity of the Gailiean satellites. Evidently the nebula near Titan was cold enough to allow the molecule Nitrogen to condense to solid form.

Thus Titan is probably made of Nitrogen ice. Because Titan is near Saturn however, which is giving off heat, it is warm enough for the evaporation of Nitrogen to form an atmosphere.

The difference between Ganymede and Titan, is that Titan formed in a region cold enough for the condensation of Nitrogen. The difference between Titan and Triton, is that Titan is presently in a region that is warm enough for the slow evaporation of Nitrogen.

The nebula was colder near Saturn, than near Jupiter. The nebula near Titan was cold enough to allow the molecule Nitrogen to become solid.

Thus Titan is probably made of Nitrogen ice, and, because Saturn is giving off heat, it is warm enough for Nitrogen to evaporate to form an atmosphere.

The difference between Ganymede and Titan, is that Titan formed in a region cold enough for solid Nitrogen to form. The difference between Titan and Triton, is that Titan is presently in a region that is warm enough for the slow evaporation of Nitrogen.

Titan formed the same way other planets did, as shown in this picture. Where Titan formed, the nebula was colder than it was near Jupiter. The nebula near Titan was so cold that even the molecule Nitrogen could become solid.

This means Titan is probably made of Nitrogen ice! Saturn is giving off heat, so it is warm enough for Nitrogen to evaporate and form the air of Titan.