TNRTB Archive - Retained for reference information
A new look at planetary habitable zones answers a criticism and strengthens the case for the anthropic principle. Because Earth has sustained life for 3.8 billion years in spite of the sun increasing its brightness by at least 18 percent, some astronomers conclude that habitable zones around stars are wide and, thus, the design needed for life may not be so fine-tuned. However, at any given time the habitable zone for a planet is quite narrow—a change in distance relative to the star of only one percent will set off either a runaway freeze-up or runaway heating. The reason why Earth has sustained life for so long is that just-right light forms were created at just-right times in just-right quantities and diversities so as to remove just-right amounts of greenhouse gases from Earth’s atmosphere. So many just-right parameters do not accord with a random universe.
James F. Kasting and David Catling, “Evolution of a Habitable Zone,” Annual Review of Astronomy and Astrophysics, 41 (2003), pp. 429-463.
RTB articles: Hugh Ross, “Anthropic Principle: A Precise Plan for Humanity,” Facts for Faith, quarter 1, 2002, issue 8, pp. 24-31.
RTB video: Journey Toward Creation, 2nd edition