例1、We might not be alone in the universe. Actually, it may be confirmed as a very crowded place by new computer models developed to help identify habitable planets.
Estimates of places where life can exist have been based on the possibility of them having surface water. But software recently developed by the Aberdeen University allows rese archers to identify planets with underground water kept liquid by heat from planets.
Water is fundamental for life and planets too close to the sun lose water to the atmosphere through evaporation. On the other hand, planets located in distant reaches from their star have their surface water locked away as ice.
Sean McMahon, who is carrying out the work, explained: "Traditionally people have said that if a planet is in this Goldilocks zone—not too hot and not too cold—then it can have liquid water on its surface and be habitable."
But this concept might change when considering that planets can receive two sources of heat—heat direct from the star and heat generated deep inside the planet.
It is easy to observe it in our own planet. As you go down through the crust (壳) of the Earth, the temperature gets higher and higher. Even when the surface is fro zen, water can exist below ground.
There could be immense quantities of water in fact—full of primitive life.
