Moons And Life

A new study of the chaotic early solar system suggests that only about ten percent of terrestrial planets will have a satellite comparable to Earth's Moon. Because the Moon's gravitational influence serves to stabilize Earth's axial orientation, thus tending to help produce predictable climates over some long term, scientists argue that such large moons are important to the development of life. If so, and if only ten percent of terrestrial planets have large moons, some argue, life may be relatively rare in the cosmos.

Well, the study suggests that arrangements like the Earth-Moon system are rare. In fact, any specific arrangement is rare, and the more exacting we get, the more rare that arrangement becomes. It's perfectly possible to define ourselves into uniqueness. The study puts a rough number to a situation already understood, however, and that is useful.

The past few decades have hosted a revolution in our understanding of life's ability to adapt to and thrive in seemingly hostile environments, so we should careful in suggesting life, or even civilization, could not survive on a world in which the climate radically changed over hundreds of thousands or millions of years. Such a situation may produce life that is aggressive, resourceful, and keenly intelligent. Understanding that Earth-like life may well be only one strand in the fabric of life in the universe is probably a good idea, too.