July 1, 2004
When Methane Made Climate
Today methane-producing microbes are confined to oxygen-free settings, such as the guts of cows, but in Earth's distant past, they ruled the world
Stories by James F. Kasting
The SciencesSeptember 1, 2003
The Origins of Water on Earth
Evidence is mounting that other planets hosted oceans at one time, but ONLY EARTH has maintained its watery endowment
Space & PhysicsFebruary 1, 1988
How Climate Evolved on the Terrestrial Planets
Planets with temperate, earthlike climates were once thought to be rare in our galaxy. Mathematical models now suggest that if planets do exist outside the solar system, many of them might be habitable