Why Titan is the only colonizable world in the solar system beyond Earth

This Voyager 2 photograph of Titan, taken Aug. 23, 1981 from a range of 2.3 million kilometers (1.4 million miles), shows some detail in the cloud systems on this Saturnian moon. The southern hemisphere appears lighter in contrast, a well-defined band is seen near the equator, and a dark collar is evident at the north pole. All these bands are associated with cloud circulation in Titan’s atmosphere. The extended haze, composed of submicron-size particles, is seen clearly around the satellite’s limb. This image was composed from blue, green and violet frames.

Cold is easier to deal with than the raging heat of Venus. The Moon and Mars are bathed in dangerous radiation. This means Titan is humanity's best existential insurance policy. Charles Wohlforth and Amanda Hendrix, authors of Beyond Earth: Our Path to a New Home in the Planets, explain:

It’s cold on Titan, at -180°C (-291°F), but thanks to its thick atmosphere, residents wouldn’t need pressure suits—just warm clothing and respirators. Housing could be made of plastic produced from the unlimited resources harvested on the surface, and could consist of domes inflated by warm oxygen and nitrogen. The ease of construction would allow huge indoor spaces.

Titanians (as we call them) wouldn’t have to spend all their time inside. The recreational opportunities on Titan are unique. For example, you could fly. The weak gravity—similar to the Moon’s—combined with the thick atmosphere would allow individuals to aviate with wings on their backs. If the wings fall off, no worry, landing will be easy. Terminal velocity on Titan is a tenth that found on the Earth.

How will we get there? Currently, we can’t.

Oh well. Doom it is, then!