Have astrobiologists really found a super-Earth?
What should we make of exoplanet GJ 357 d?
Published: 13 August 2019 (GMT+10)
The headlines seem like science fiction, conjuring up images from the movie “Another Earth”. Is there possibly life on another planet like ours? Researchers at the Carl Sagan Institute at Cornell University discovered what may be an Earth-like planet, 31 light years away from our solar system.1,2
Red dwarfs and their planets
The planet is called “GJ 357 d” and is about six times the mass of our own Earth and orbits a red dwarf star called “GJ 357” once every 55.7 days (figure 1). Two other planets closer to the star have been detected labelled GJ 357 b and c. GJ 357 b was detected by the transit or photometric method: when it passes in front of the star, it slightly dims the star’s light.3 Planets c and d do not seem to transit the star, so were detected by radial velocity method (See Planets around other stars for how extrasolar planets are detected.)
Red dwarf stars are by far the most common type of star but are all too faint to be seen with the naked eye. The star GJ 357 is no exception: it is only about a third of the sun’s mass and diameter, but its temperature is quite cool, 3505 ± 51 K, and is only 1.6% as bright as the sun.4 There are huge problems with planets around red dwarf stars that make them unsuitable for life, as discussed in the our article about the ‘ultracool’ star Trappist-1 and its seven planets.
One major problem is that because the star is so faint, the habitable zone, where liquid water is possible, is very close to the star. This means any planets in the zone will be tidally locked, i.e. it will keep the same face towards the star. Thus, one side is perpetual day, so it fries; while the other side is perpetual night, so it freezes.
GJ 357 d is claimed to be in the habitable zone and has a rotation period between 70 and 120 Earth days. Such a slow rotation suggests at least partial tidal locking. Evolutionists think that this way the temperature on the planet is neither too hot nor too cold and is just right for life to evolve. Scientists are already announcing the possibility of alien life on this super-Earth. If habitable, they claim it would be worth visiting. However, as it has been shown on our website, it is quite impossible to do so.
If this planet does harbor life, then secularists would draw the obvious conclusions, that Earth is not special, because life evolved elsewhere in the universe. Furthermore, they would claim that the Bible is incorrect when it says that God created life only on Earth.
Should we really be so excited? What did the researchers really find?
Crying wolf 200 times
As always, this might simply be just media hype as opposed to real science.5 For example, the major paper on this stellar system3 devotes little space to GJ 357 d; its main concern is GJ 357 b. However, b and c are too hot for life: water would boil on their surfaces. In particular, the temperatures at the equator of b and c were 525 K and 401 K respectively,6 while water boils at 373.13 K (at sea level). But then, the original authors were hardly blameless, e.g. Cornell University’s own news site reported on the team leader of Ref. 1:
“This is exciting, as this is TESS’s first discovery of a nearby super-Earth that could harbor life – TESS is a small, mighty mission with a huge reach,” said [Lisa] Kaltenegger, associate professor of astronomy, director of Cornell’s Carl Sagan Institute and a member of the TESS science team.7
However, even GJ 357 d, while supposedly in the habitable zone, is hardly habitable as we would know it. The authors admit that even though the position of GJ 357 d is in the hospitable zone of the GJ 357 star system, it is in a position which is even colder than that of Mars in our own solar system, which is much less inhabitable than Earth, if at all. In particular, the temperature at GJ 357 d’s equator is only 219.6 K,6 while water freezes at 273.15 K. So the researchers must postulate a thick atmosphere of CO2 to produce an intense ‘greenhouse effect’ to warm the planet’s surface enough to support liquid water.
Also, this planet has over six times the mass of Earth, so if it were rocky like ours, a ‘super-earth’, it would have a crushing gravity. But if it were a small ice giant, a ‘mini-Neptune’, its solid surface would be under hundreds of miles of thick atmosphere. The authors admit that many further studies are needed to confirm whether GJ 357 d is truly habitable. GJ 357 d is actually just one of around 200 so-called exoplanets (planets discovered outside our own solar system) orbiting sun-like stars, yet until now not one of them was shown to have life on it. For example, another exoplanet, called Kepler-452b was discovered in 2015, which was 1,400 light years away from us, and was five times as large, with a diameter 60% larger than Earth. Yet the news came and went, and it was never ultimately demonstrated that this planet harboured any form of life. And more sober research showed that Trappist planets are not found in the habitable zone.
Even the composition of the atmosphere of GJ 357 d is not yet known. Neither do they know whether the planet even has oxygen or water, or whether the surface of the planet is rocky or not. This will only be studied starting from 2021 when two telescopes will make more in-depth analyses. Thus, it is much too early to claim that GJ 357 d is inhabitable.
Showing that an exoplanet could possibly be inhabitable is not the same as demonstrating that it really is. Just because an exoplanet like GJ 357 d may have water or other chemicals essential for life does not mean that life has actually evolved on it. The characterization of the atmosphere of exoplanets is admittedly a hard task. Simple chemicals only mean that the very first step in chemical evolution is hypothetically possible on this other planet.
Evolution is a very difficult, highly improbable process which needs to overcome a long series of highly improbable hurdles. For example, one such hurdle is the simple formation of a single cell on Earth, which has only the very minute probability of about 10-167,500.
This news story about a super Earth in another part of the universe is yet another false alarm together with all the previous 200 candidate exoplanets. Evolutionary astrophysicists have had the same success as 40 years of the SETI program of not finding intelligent life in the universe outside the Earth.
Earth is the only place in the universe which has life on it. Isaiah 45:18 says:
“For thus says the Lord, who created the heavens (he is God!), who formed the earth and made it (he established it; he did not create it empty, he formed it to be inhabited!): ‘I am the Lord, and there is no other.’” (emphasis added)
During the days of creation God describes in detail how He formed the Earth and created the different lifeforms on each of the six days. The sun and stars are only briefly mentioned on Day 4 (not even mentioning exoplanets). To assume that life exists in some other parts of the universe is a huge argument from silence.
Most importantly, we know that intelligent life would not exist outside the Earth. Why would God curse intelligent beings on other planets because of Adam’s sin? The curse extended to the whole universe. That is why 2 Peter 3:13 says:
“But according to his promise we are waiting for new heavens and a new earth in which righteousness dwells.” (emphasis added)
Revelation 21:1 describes the recreation of heaven and earth:
“Then I saw a new heaven and a new earth, for the first heaven and the first earth had passed away, and the sea was no more.” (emphasis added).
God created life on Earth alone, so that He could have a special relationship with us. Only we humans bear God’s image. We alone are the special focus of God’s attention. As such let us give glory to God alone.
References and notes
- Kaltenegger, L. and seven others, The Habitability of GJ 357 d : Possible Climates and Observability, arxiv.org/abs/1907.13215, submitted 30 Jul 2019. Return to text.
- The Habitability of GJ 357 d: Possible Climates and Observability, astrobiology.com, 31 July 2019. Return to text.
- Luque, R. and 75 others, Planetary system around the nearby M dwarf GJ 357 including a transiting, hot, Earth-sized planet optimal for atmospheric characterization, Astronomy & Astrophysics, accepted 27 June 2019 | doi:10.1051/0004-6361/201935801. Return to text.
- Lugue et al., Ref. 3, Table 1. Return to text.
- E.g. Yancey-Bragg, N., Astronomers have discovered a ‘super-Earth’ just 31 light-years away. But, is it habitable or glacial? usatoday.com, 31 July 2019. Return to text.
- Lugue et al., Ref. 3, Table 5. Return to text.
- Friedlander, B., TESS satellite uncovers its ‘first nearby super-Earth, news.cornell.edu, 31 July 2019. Return to text.