How can liquid be found so far out in the solar system where temperatures are so cold?

Answer 1

Some elements and compounds require extremely low temperatures to freeze. For example, hydrogen freezes at 14 K, which is only 14 degrees above absolute zero and equal to about 259 degrees below zero C or 434 degrees below zero F, and it boils at about 20.3 K (-252.9° C or -423.2° F).

Another example is methane. That seems to be in liquid form on the moon Titan.

Also temperatures are higher inside the gas giants than they are on the surface. Pressure also increases inside these planets. So we believe the liquid hydrogen inside Jupiter is in fact at a high temperature and pressure. The overall result is that it is a liquid.

Remember that temperatures and pressures inside planets (and moons to some extent) can be much higher than on the surface.

For example, scientists think there may be an "ocean " of liquid water under the thick ice that covers Jupiter's moon Europa.

Answer 2

Liquid in the outer solar system, such as on moons like Europa or Enceladus, can exist due to tidal heating generated by gravitational interactions with neighboring bodies. This can melt subsurface water ice and create liquid water oceans beneath the icy crust despite the cold temperatures.