Life in our Solar System

Before we discuss life in other planetary systems, let's first review the so far unsuccessful search for life beyond the Earth in our own Solar System. animated introduction to the Viking search for life on Mars.

The adjacent image shows the first strong case for water in a meteorite (Ref). This chondrite, which fell near a group of boys playing near Monahans, Texas, in 1998, contains blue salt crystals called halite. Chemical analysis confirms the presence of water in the salt crystals. The material has been estimated to be 4.5 billion years old, implying that there was salty water present on the asteriod from which this meteorite came early in the history of the solar system. This meteorite was examined carefully only two days after it fell. It is speculated that other meteorites may contain water, but the evidence for it has disappeared before water could be confirmed.