On earth we have the following (among many others) extremophiles: Hyperthermophiles that thrive at temperatures between 80 and 122 °C Acidophiles that thrive in extremely acidic environments Thermoacidophiles that thrive in environments that are both very hot and very acidic Cryophiles that survive and reproduce in unusually cold conditions Radioresistants that are resistant to high levels of ionizing, ultraviolet and nuclear radiation Anaerobes that do not require oxygen in order to survive In fact there are entire ecosystems that surround volcanic vents at the bottom of oceans where there is enormous hydrostatic pressure, high temperatures and not a trace of sunlight. The point is that life doesn't appear to need conditions that we consider to be moderate. In fact what we consider to be moderate is of course merely a reflection of the conditions that we have adapted to, that have shaped us into what we are. The more one learns about and reflects upon all of this, the more it seems not just possible but even likely that if intelligent life exists on some other planet out there, to them we would seem like the extremophiles. Life-forms that have somehow miraculously evolved in the harshest of conditions. After all, oxygen is a corrosive gas you know.