This not only goes for water, but any hot, melted substance suddenly exposed to the near vacuum of space. For example, suppose I have a stream of water leaking out of a space ship. Does the water freeze because space is at 50-100 K (in our solar system), or does it evaoprate because the air pressure of space is so low? Or, is it more complicated than that where some of the water will freeze on the outside of the spaceship, and some will escape through the solar system as gas? This also applies to super-hot lava erupting on moons of Jupiter or Saturn. The lava is very hot ~1000-2000 K. The temperature of such moons is ~50-100 K. So, by this reasoning, the lava would freeze into rock. But, these moons also do not have any atmosphere, thus they have very low pressure. Low pressure makes almost the phase of everything a gas, so by the second line of logic, the lava should outgas into space. I can't see which is which, so I ask for help here.