Many Earth-Sized Planets

My kids and I often wonder where various idioms originate from. Our most recent musings dealt with the request to “cut me some slack.” Perhaps the root of “barking up the wrong tree” is easier to decipher. Yet, one should take the latter advice to heart in trying to understand the apologetic implications that the recent flood of exoplanet data brings.

An article published in Science highlights one tree to avoid barking at. Most of the roughly 500 exoplanets discovered to date have masses similar to (or larger than) Neptune’s. However, this latest study shows that the number of planets increases as the mass of the planet decreases. Consequently, the authors of the study conclude that nearly one quarter of all Sun-like stars host an Earth-sized planet orbiting in the hot-zone close to the star.1 This result implies an even greater fraction of stars with Earth-sized planets orbiting at distances corresponding to the habitable zone.

I thought this a fitting opportunity to outline RTB’s position as it pertains to planets outside the solar system.

Genesis 1 describes the miraculous transformation of Earth from “formless and void” to teeming with a great diversity of life. As Isaiah 45:18 explicitly states, God created the Earth to be inhabited. Consequently, we should expect advances in our understanding of Earth’s history to uncover evidence that Earth is fine-tuned to support life. Genesis 1 describes these miraculous transformations as occurring after Earth came into existence; but the Bible infers that the divine fine-tuning extends to the planet’s formation as well.

Scientific research has uncovered a wealth of evidence supporting this fine-tuning hypothesis. These empirical evidences range from Earth’s location, the type of galaxy in which it resides, the solar system’s birthplace, and even the laws of physics that govern the universe.

Scientific advances over the last two decades allow astronomers to detect planets orbiting stars outside our solar system, hence these objects are known as extrasolar planets, or exoplanets for short. With hundreds of these exoplanets already discovered, the evidence for Earth’s unique (or at least rare) capacity to support life continues to grow. Occasionally, one of these exoplanets generates news as being Earth-like or “habitable.” Typically, such announcements assume a “minimalist model” for making a habitable planet, namely that where liquid water exists, life will inevitably follow. In contrast, RTB argues that life requires far more exacting criteria. After all, Genesis 2 describes the initial conditions of Earth as formless and void (or desolate and uninhabitable) even though water covered the planet’s surface.

The contrast between RTB’s model and the more popular minimalist model provides a wealth of tests as scientists find more exoplanets. These planets will often exhibit a subset of the requirements noted by RTB’s model (as noted in the Science article), but rarely all of them. If future observations of these partially-Earth-like planets show no signs of life, such results will add to the body of evidence that supports RTB’s model.

1. Andrew W. Howard et al., “The Occurrence and Mass Distribution of Close-in Super-Earths, Neptunes and Jupiters,” Science 330 (October 29, 2010): 653–55.


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