Tuesday, January 16, 2007

RTB du jour

From Hugh Ross’s (more or less) daily reason to believe:

Studies of planet formation continue to reveal the fine-tuning of the solar system to ensure Earth can support life. During formation of planets, gas giants form before rocky terrestrial planets do. Earlier research showed that gas giants with eccentric orbits prevented the formation of earth-sized, watery planets. Now, a team of international scientists has shown how interactions of gas-giant planets with the disks of debris around their stars cause the eccentricity of the gas giants to grow-even if their orbits were initially circular. One feature of our solar system that remains unique among all known planetary systems is the very circular orbits of multiple gas giants. This circularity ensures the gravitational stability of Earth through time and also provides an environment for Earth’s growth and accumulation of water. Such fine-tuning comports well with the idea of a supernatural Designer fashioning a habitable planet where humans can dwell.

Gennaro D’Angelo, Stephen H. Lubow, and Matthew R. Bate, "Evolution of Giant Planets in Eccentric Disks," Astrophysical Journal 652 (2006): 1698-714.

It often goes unappreciated how the gas giants (especially Jupiter) in our solar system (a) shield us (by a reduction factor on the order of 1000) from catastrophic impacts and (b) help stabilize our orbit. These properties require (1) the gas giants being outside our orbit, far from the sun and (2) the gas giants having a circular orbit.

Though we discover more and more planetary systems around other stars, we have yet to find any with these conditions.

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