3 Ways Planet Earth Stands Out

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 1020 terrestrial planets!1 For comparison, somewhere between 1022–1024 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 8–8.4 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?

Endnotes

  1. Erik Zackrisson et al., “Terrestrial Planets across Space and Time,” Astrophysical Journal, preprint, submitted February 1, 2016, http://arxiv.org/abs/1602.00690.
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8 thoughts on “3 Ways Planet Earth Stands Out

  1. Although I don’t think we’ll ever know for sure if there is life on other planets, I do find it hard to believe God would only create one inhabitable planet, galaxy, or universe. However, I do think we on Earth are the only ones of our kind ever to be created. We had a sole purpose, and are created uniquely in the image of God, with a piece of His spirit. If there is life elsewhere, they probably lack that quality.

  2. I once thought the universe must be filled with other life forms, but the more I learn about Earth’s uniqueness (thanks RTB!) and contemplate the deep mysteries of life that God gradually reveals in nature and His Word, the more I become convinced that Earth is the only place of physical life in this universe. God created this universe as a temporary dwelling place for a collection of physical people with free will made in His image that He would save for His pleasure and eternal glory. To God, the size and age of this universe is virtually nothing. He will roll it up and take it away when its purposes are done, and create new dwelling places and life forms that are beyond our present ability to fathom.

  3. God created the universe, multiverse. If, and I say if, there is intelligent life on other planets why are these intelligent life forms so far apart. If there is intelligent life on a planet in the tri- star system of Alpha Centauri and we sent a message to this planet it would take 8.74 years to receive a reply. If we sent a message to a planet in the Andromeda Galaxy, to nearest spiral galaxy to the Milky Way, we would have to wait 4 million years for a reply. There are so many Goldilocks zones that are required for intelligent life. There is most likely other life on other planets. But intelligent life? The odds against it are staggering.

  4. How might ET life alter / adjust / refine our biblical understanding of Christ’s atoning death & resurrection ; AND God’s special creation of life and unique creation of Adam & Eve? Hard to transplant these bedrock doctrines to other planets (CS Lewis classic trilogy notwithstanding and which required humans from Earth). Unless we’re talking “simple” life forms which still involve complexities as Fuz had shown.

  5. If life does exist elsewhere in the universe, I think it would only further support evidence for God, rather than “disprove” God. I am proud to be the crown of His creation, but I would also consider it an honor to encounter other life that He had created.

  6. Dear Jeff,

    That was a great article and I agree with its concluding points. It never ceases to amaze me how easily many folk wish to give up their ‘sovereignty’ as creatures uniquely made in the image of God. For me, and this is just a gut feeling; I believe that God created life on Earth uniquely as a personal expression of His glory. We will go on seeking life and other worlds but over time, we will probably discover that it doesn’t seem to exist, and all the while, we are forced to think about how special we really are. The triune God of the Bible has an ‘ace card’ to bring us to faith and that ace card is life.

    Sincerely,

    Neil English

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