Doubling the Exoplanet Catalog

Doubling the Exoplanet Catalog

A recent article published by Fox News contains some bold claims. The article describes the preliminary analysis of the first six weeks of data from NASA’s Kepler Mission, which searches for planets orbiting stars other than our own Sun. According to one of the Kepler scientists, “the Milky Way will contain 100 million habitable planets, and soon we will be identifying them.” He goes on to say that “the statistical results are loud and clear, and it is that planets like our own Earth are out there.” How do these results impact RTB’s creation model, which argues that Earth is unique (or at least rare) in its capacity to support life? Let’s look a little more closely.

To begin, one should not understate the dramatic nature of the results published by Kepler. In the 15 years since the first exoplanet was detected, astronomers have discovered just under 500 planets outside our solar system. In a paper submitted for publication in the Astrophysical Journal, the Kepler team announced the detection of 706 new planets—more than doubling the number of detected exoplanets!1 During its last commissioning phase (9.7 days) and first science-mode operations (33.5 days), Kepler has observed over 150,000 stars. Since Kepler uses the transit technique (see the page 5 article in our e-Zine, New Reasons to Believe), the observations give good detail on the physical size of the planets. Specifically, the technique enables astronomers to detect planets smaller than Neptune. In contrast, the radial velocity technique—which accounts for most of the ~500 planets detected before Kepler—primarily finds Jupiter-sized and larger planets. 

The paper describes the characteristics for 306 of the Kepler planet candidates—the other 400 will be released later after follow-up observations and more thorough analyses. However, the characteristics of these 306 candidates show the reason for the bold assertions about finding habitable planets like Earth. First and foremost, the bulk of these candidates are smaller than Neptune. In particular, the size distribution of planets confirms previous findings that the number of planets increases as the size of the planet decreases. This implies that more sensitive instruments will find more Earth-sized planets than Neptune-sized planets. If more than one in 1,000 stars has a Neptune-sized planet, as many as one in 10 may have an Earth-sized planet, assuming the expected trend continues. And some fraction of these will orbit in the zone where liquid water could exist on the planet.

Personally, I expected such a discovery would occur as we developed more sensitive detectors. The uniqueness of Earth to support life is not exclusively related to its location around the Sun—although that is one critical component. I also expect that we will find numerous planets that start out covered in liquid water (assuming we develop sensitive enough equipment). Explorations of our solar system demonstrate that these are necessary but not sufficient conditions for building a habitable planet.

A growing body of evidence shows that Venus, Earth, and Mars each started out covered in water. All three planets also reside in or close to the habitable zone. So, if a Kepler-like mission were viewing our solar system, it would see three “habitable” planets around the Sun. However, from Earth we see that only our planet remains habitable four billion years after formation or shows any definitive signs of ever supporting life. Such results match expectations from the biblical description.

The fact that Earth started with water did not make it habitable (see Genesis 1:2), but the miraculous transformations starting from that water-covered state did.

Numerous transformations occurred in Earth’s history that permit the diverse and abundant life we see today. RTB’s creation model predicts the rarity of a truly habitable planet like Earth while anticipating the discovery of planets that resemble—in part—many of Earth’s life-sustaining characteristics. Scientific research continues to validate this component of RTB’s model.

William J. Borucki, for the Kepler Team, “Characteristics of Kepler Planetary Candidates Based on the First Data Set: The Majority Are Found to Be Neptune-Size and Smaller.” Preprint, submitted June 14, 2010,