Big Questions for Phoenix Microbial life forms have been
discovered on Earth that can survive and even thrive at extremes
of high and low temperature and pressure, and in conditions of
acidity, salinity, alkalinity, and concentrations of heavy
metals that would have been regarded as lethal just a few years
ago. These discoveries include the wide diversity of life near
sea–floor hydrothermal vent systems, where some organisms live
essentially on chemical energy in the absence of sunlight.
Similar environments may be present elsewhere in the Solar
System. For the first time in human history we know of planets
around other stars and many of those other planetary systems
look quite different from our own. Many have a planet like
Jupiter, or even bigger, nearest to the Sun. If we are to
understand why this is the case, and how likely it is that there
are Earth-like planets elsewhere, we need to better understand
how planets form. The possibility of finding life elsewhere is
for many people the most compelling reas