Titan is now known to be smaller than Jupiter’s Ganymede. Its diameter
is less than 5120 kilometers (3180 miles), which implies a density twice
that of water ice. A dense, hazy atmosphere at least 400 kilometers (250
miles) thick obscures the surface. Voyager 1 determined that Titan has a
nitrogen-rich atmosphere (as does Earth), but with concentrations of
hydrocarbons such as methane (natural gas), ethane, acetylene, ethylene,
and deadly hydrogen cyanide. The haze layers merge into a darkened hood
over the north pole. At the poles, liquid nitrogen lakes may form. The
surface temperature is probably near 100 kelvins (-280° Fahrenheit),
only slightly warmer than the boiling point of liquid nitrogen.
Titan has no appreciable magnetic field and therefore possesses no large
liquid conducting core. It does, however, supply a small amount of
charged particles to Saturn’s magnetosphere.
The southern hemisphere is somewhat brighter than the northern, perhaps
as a result of seasonal effects.