Where Science and Faith Converge

3 Ways Planet Earth Stands Out

By Jeff Zweerink - March 24, 2016

Is Earth special? A large fraction of the scientific community doesn’t think so. In fact, most have adopted the Copernican principle, believing that Earth’s capacity to support life is commonplace. However, a number of factors indicate that Earth may be rare (or possibly unique) in its capacity to support life—even among the 100 sextillion terrestrial planets in the observable universe, according to a recent paper.

In two decades, the exoplanet catalog has grown to over 2,000 known exoplanets. Using data from those planets and host stars, astronomers have developed models to determine information about planets not yet discovered. Based on those models, astronomers have estimated that the observable universe contains around 1020terrestrial planets!1 For comparison, somewhere between 1022 and 1024 stars exist in the observable universe, so roughly one in a hundred stars have rocky planets. These models also allow astronomers to compare terrestrial exoplanets to Earth. Amidst the comparisons, Earth stands out in at least three ways.

1. Age: Earth is younger.

While most terrestrial exoplanets are between 8 and 8.4 billion years old, Earth is much younger—only 4.5 billion years old. Why is such a young planet habitable? This is probably because older planets (that formed earlier in the history of the universe) are subject to dynamical and radiation effects that diminish the possibility of hosting life.

2. Galaxy type: Most planets reside in the wrong galaxies.

The number of planets per star remains largely constant with galaxy size, so most terrestrial planets reside in galaxies about twice the size of the Milky Way. However, the vast majority of galaxies this large are not spiral but elliptical. Consequently, most of the terrestrial planets in the universe reside in ellipticals, but research suggests that truly habitable planets must orbit stars in a spiral galaxy—such as the Milky Way.

3. “Dangerous” neighbors: Earth has none.

Most planets that orbit otherwise life-friendly stars might have any hypothetical life exterminated due to radiation from nearby supernovae, gamma-ray bursts, active galactic nuclei, or dark matter annihilation regions. Dynamical encounters with interstellar gas clouds or dark matter clumps could also disrupt the stability of potentially habitable planets.

One theological point warrants discussion. The Bible gives much information about God’s activity to bring about human life here on Earth, but it says nothing about whether He performed similar work somewhere else in the universe. Except for angelic beings (they have no physical body), the Bible leaves open the question of whether life exists elsewhere in the universe. However, it emphatically states that all things exist because of His divine action (see John 1:1–3).

It seems likely scientific discoveries will continue to provide a growing body of evidence that Earth’s habitability is the exception instead of the rule. Astronomers have much work to do before they have the capacity to determine whether life exists beyond Earth, but the search is interesting from both a theological and scientific perspective.

Food for Thought

Would finding life on a planet outside our solar system diminish the case for God? Visit TNRTB on Wordpress to comment with your response.

  1. Erik Zackrisson et al., “Terrestrial Planets across Space and Time,” Astrophysical Journal, preprint, submitted February 1, 2016, https://arxiv.org/abs/1602.00690.

  • Exoplanets
  • Astronomy
  • Blogs

About Reasons to Believe

RTB's mission is to spread the Christian Gospel by demonstrating that sound reason and scientific research—including the very latest discoveries—consistently support, rather than erode, confidence in the truth of the Bible and faith in the personal, transcendent God revealed in both Scripture and nature. Learn More »

Support Reasons to Believe

Your support helps more people find Christ through sharing how the latest scientific discoveries affirm our faith in the God of the Bible.

Donate Now

U.S. Mailing Address
818 S. Oak Park Rd.
Covina, CA 91724
  • P (855) 732-7667
  • P (626) 335-1480
  • Fax (626) 852-0178
Reasons to Believe logo

Reasons to Believe is a nonprofit organization designated as tax-exempt under Section 501(c)3 by the Internal Revenue Service. Donations are tax-deductible to the full extent of the law. Our tax ID is #33-0168048. All Transactions on our Web site are safe and secure.

Copyright 2020. Reasons to Believe. All rights reserved. Use of this website constitutes acceptance of our Privacy Policy.