Will the James Webb Space Telescope find extra-terrestrial life?

Will habitable-zone planets have life-supporting atmospheres?


The James Webb Space Telescope

High expectations come with the long-awaited James Webb Space Telescope (JWST), 10 billion dollars and 25 years in the making. Set to launch from French Guiana on 18 December 2021, NASA has dubbed it as the successor to the famous Hubble space telescope.

Hubble launched in 1990 was the first major optical telescope to be put into space. Considered to be one of the greatest scientific projects, it has revolutionised modern astronomy and awed people worldwide with its incredible deep field images.

The JWST primary mission objective is to examine the first light in the Universe (Evolutionist-speak for examining the galaxies which are furthest away.) But another aim is to study the properties of exoplanets, specifically to detect and analyse their atmospheres. It is hoped that this will further establish whether a known exoplanet could be habitable to potential alien life.

The search for extra-terrestrial life

The hunt for extra-terrestrial life today is fuelled by the evolution story. The reasoning goes, if life evolved spontaneously on Earth, then surely it should have evolved somewhere else too?

The Hubble Space Telescope launched in 1990 and was the first major optical telescope to be put into space. Considered to be one of the greatest scientific projects, it has revolutionised modern astronomy and awed people worldwide with its incredible deep field images.

The moon

Ideas about the moon were rather nebulous until Galileo invented the telescope and pointed it to the moon in 1609. He discovered that the moon’s surface features cast shadows that changed in length throughout the night. Understanding that the moon was a physical place with terrain like the earth’s,1 gave rise to popular science writers entertaining the possibility of life on the moon throughout the 18th, 19th and even the 20th Century.2 However, ongoing observation of the moon showed that the moon’s surface features did not change their shape or appearance, which indicated a lack of weather. By the 1800s, scientists knew that the moon had no atmosphere, and therefore no intelligent life. A thorough analysis of lunar rocks brought back by the Apollo 11 mission in 1969 confirmed that not even microbial life existed on the moon. The moon’s conditions are hostile to life—no liquid water, a very small magnetic field, and massive temperature swings; from –183°C in the night to 106°C in the daytime!



The surface environment of Venus was believed to be similar to the earth’s, and hence it was widely believed that Venus could harbour life. This conjecture was helped because, unlike the moon, telescopic pictures showed that Venus had an atmosphere and weather (see the clouds in picture).

Speculation of life existing on Venus decreased significantly in the early 1960s, when spacecraft began studying Venus. We learned that Venus has a crushing atmosphere of 9.3MPa (90 times that on Earth), which mostly consists of carbon dioxide, which produces an enormous ‘greenhouse’ effect. Thus, Venus has an average night time surface temperature of 425°C (hot enough to melt lead). Furthermore, its clouds are composed of sulfuric acid! These findings shifted the focus of extra-terrestrial life exploration to Mars.


The temperature on Mars can reach above freezing (varies from –153°C to 20°C) but liquid water is unstable over much of the planet, as the very low atmospheric pressure causes ice to sublime directly into water vapour. To date, the closest we have come to discovering liquid water on Mars is in the detection of subglacial lakes, below 1.5km of ice.3

It was the 1976 Viking lander mission to Mars that effectively ruled out the possibility of multicellular extra-terrestrial life in our own solar system.4 The two landers, as per the main mission objective, conducted three biology experiments designed to detect possible signs of life. No signs were found.

Scientists now know that the Martian surface cannot sustain life. The soil is too oxidizing, and bathed in too much of the sun’s UV radiation, both of which destroy organic molecules.

Outside the solar system

So the greater hopes for finding complex extra-terrestrial life are now directed to investigation beyond our solar system.

Only recently have we answered the fundamental question, do other stars have planets? While any observer without a telescope can see other stars in the night sky, identifying potential planets orbiting these stars is very difficult. Detecting planets has only been possible with advanced telescopes, increased computing power, and sophisticated algorithms.

Astronomers first confirmed an exoplanet orbiting a main sequence star in 1995,5 Michel Mayor and Didier Queloz discovered a gas giant orbiting close to its sun-like star 51 Pegasi, 50 light years away in the constellation of Pegasus. The planet is named 51 Pegasi b or Dimidium. The discoverers shared half the 2019 Nobel Prize for Physics.6

This planet orbits so close to its star that it would be red hot, so is called a ‘hot Jupiter’. This is clearly not suitable for life. Since then thousands of exoplanets have been detected, and special attention is being paid to those most similar to Earth.

The drive behind this research is not hidden; NASA’s exoplanet exploration site contains a quote from Sara Seager, professor of planetary science and physics at MIT:

If we can identify another Earth-like planet, it comes full circle, from thinking that everything revolves around our planet to knowing that there are lots of other Earths out there.7

This is at odds with the biblical account that the earth and mankind are central and special in God’s creation.

If you have seen exoplanet discovery news reports, you could be forgiven for thinking we have already discovered Earth-like planets inhabited by extra-terrestrial life. Headlines typically include: ‘earth 2.0’, ‘planet in the habitable zone’, ‘temperatures for liquid water’, etc.

Habitable zone

Artist impressions of Exoplanets

Part of this miscommunication is because of confusion around the term ‘habitable zone’. A planet in the ‘habitable zone’, may invoke images of liveable worlds, with oceans, landmasses, vegetation, and alien creatures. However, the ‘habitable zone’ being talked of in the scientific literature and associated press is simply the distance a planet needs to be from its host star to give temperature ranges that allow liquid water on the surface. Because of this confusion the habitable zone is increasingly, more accurately, labelled the Circumstellar Habitable Zone (CHZ). Although this term still doesn’t completely convey the true meaning, it does indicate that there are other habitability requirements that an exoplanet needs to meet for the possibility of sustaining any life, even single celled or extremophile life. We start with the liquid water requirement because liquid water is the common ecological requirement for life on Earth. Hence, exoplanet surface temperature is the first parameter to consider both because of its influence on liquid water and because it can be directly estimated from orbital and climate models of exoplanetary systems.

How close are we to finding exoplanet surface temperatures?

Circumstellar Habitable Zone (CHZ)

While 608 of the 4284 confirmed exoplanets (as of Oct 2020)9 have been found within the conservative CHZ of their star, this does not mean that they are able to sustain liquid water on their surface! Several other prerequisites would need to be met (e.g. close to circular orbit, planet spins on its axis, right amount and composition of atmosphere, stable host star of the appropriate size) for a planet to be capable of sustaining liquid water.

If we simply focus on the factors that would allow for the correct average surface temperature for liquid water, then the next detectable indicator is the presence of an atmosphere of the correct thickness. We can see that the planet’s atmosphere is critical to the question of temperature by looking at Mars and Venus. Too thick an atmosphere like Venus’ would retain too much heat, and too rarefied an atmosphere like Mars’ would result in low surface pressures at which water cannot exist as a liquid.

Exoplanet atmosphere

Detecting and analysing exoplanet atmospheres is a much more difficult task than analysing the atmosphere of Venus or Mars. Exoplanets are much further away and the planet itself is often optically indistinguishable from its host star.

Webb’s image quality superiority over Hubble is partly due to its much larger mirror. (6.5 metres in diameter compared to 2.4 metres).

If the orbit of an exoplanet causes it to pass between the host star and an observer, the exoplanet is said to transit its star. By measuring how the absorption spectrum of a star changes as the exoplanet transits, the exoplanet’s own atmospheric volume and content can be inferred. But because stars are big compared to their orbiting planets, the exoplanet absorption effects are relatively small and hard to detect. Despite this, several exoplanet atmospheres have been detected. But almost all atmospheric detections to date belong to ‘hot Jupiters’ or ‘hot Neptunes’. These are large gaseous exoplanets that orbit very close to their host star and thus have heated and extended atmospheres, making them more easily detectable. A thin atmosphere of a planet in the CHZ, as required for life, is much more difficult to detect, let alone analyse.

The current holy grail in the search for habitable exoplanets is to detect and analyse the atmosphere of a rocky (earth size) planet in the CHZ. This is something that researchers from University College, London, claimed to have achieved in September 2019 in their paper, ‘Water vapour in the atmosphere of the habitable-zone eight-Earth-mass planet K2-18 b’.10 Using the Hubble Space Telescopes Wide Field Camera 3 they were able to obtain a spectrographic signature for K2-18. From this they were able to determine the effects of the atmosphere of planet K2-18, revealing the absorption spectra for water.

Commentators noted that the research team’s achievement proves that the atmosphere is much too thick to have habitable temperatures. Harvard Professor of astronomy, David Charbonneau said:

If the planet had a thin secondary atmosphere similar to Earth it would be so thin that Hubble couldn’t detect it.11

Current telescopes do not have the sensitivity to detect thin, habitable atmospheres of exoplanets in the CHZ. This is why the James Webb Space Telescope is an exciting step forward in the search for a habitable exoplanet.

The James Webb Space Telescope

The JWST is a larger and more powerful telescope than the Hubble.

Webb’s image quality superiority over Hubble is partly due to its much larger mirror.

It is an infrared telescope, which means it will take images at infrared wavelengths, whereas the Hubble takes images primarily at UV and visible wavelengths.

JWST instruments will see wavelengths from 0.6 to 28 micrometres (1 micrometre is 1 x 10-6 meters). The infrared part of the electromagnetic spectrum spans from 0.75 micrometres to a few hundred micrometres. This means that Webb’s instruments will work primarily in the infrared range of the electromagnetic spectrum, with some capability in the visible range (the red and up to the yellow part of the visible spectrum). The instruments on Hubble can observe a small portion of the infrared spectrum from 0.8 to 2.5 micrometres, but its primary capabilities are in the ultra-violet and visible parts of the spectrum from 0.1 to 0.8 micrometres.

Because more distant objects tend to emit light that has been redshifted and the infrared wavelengths better penetrate gas and dust, the JWST will be able to see further and clearer than the Hubble. The infrared spectrum is also where the largest number of spectral features in exoplanet atmospheres is found. So not only will JWST obtain more accurate exoplanet surface temperatures, it will also be better at detecting bio-signatures, that is, reactive chemicals that are unlikely to have an abiotic source.

So hopefully in late 2021 and beyond we will see JWST make new exoplanet atmospheric discoveries. I suspect that we will see another wave of exoplanet excitement in the press, more ‘earth 2.0s’, and more speculation of extra-terrestrial life.

But when you see these press releases please consider:

  • A viable atmosphere is just one more filter towards possible conditions for surface water. Others exist, for example, is the star which the exoplanet orbits sufficiently stable? Most stars are much less stable than the sun. Even those that are the same size, composition, and brightness as our sun erupt in super flares 100 to 100 million times the strength of our sun’s flares.12 Just one of these flares could rid a planet of liquid water.
  • The reported composition of these newly discovered exoplanet atmospheres. Earth’s atmosphere is uniquely designed for life in its layering and its composition. Even the presence of oxygen, though considered the most crucial biomarker for life, can be produced via methods other than photosynthesis.
  • The Bible suggests that the universe had a watery beginning, so finding water—solid, liquid, or gas—in an atmosphere or on the surface of a planet, past or present could be expected (2 Peter 3:5).
  • We need much more than liquid water to survive! In fact, water is an enemy of chemical evolution, because it hydrolyzes the large molecules needed. Life is the result of special creation—the enormous amounts of information in the form of DNA found in the cells of all living creatures testifies to this.
  • Extra-terrestrial life is an idea borne out of naturalism, the belief God did not create but that everything can be explained by natural laws and processes. Evolution is the product of this belief system. The evolutionist thinks that, if life spontaneously arose on our ‘insignificant planet’, then it is highly likely to have spontaneously arisen elsewhere. However, after a century or more of research, there is still no plausible evolutionary explanation for how life could have spontaneously arisen from non-living chemicals.
  • So far, every star system discovered is very different from our own solar system.
  • All discovered exoplanets appear basic and barren compared to the earth. That is not to say that exoplanets and stars are not extraordinary. Their size and appearance glorify God (Psalm 19:1). Rather the features of exoplanets confirm that the earth is central to the Creator’s purpose for the universe. Earth is beautiful, complex, and life-sustaining. It was the first astronomical object God made, He spent several days creating it, compared to the one day in which He made all the stars and exoplanets. Most importantly, God’s own Son was sent to Earth!

ET vs the Bible

From a biblical perspective it is highly unlikely that intelligent extra-terrestrial life exists. The Bible gives no indication that sentient beings similar to humans have been made elsewhere. Jesus is our Kinsmen redeemer (Isaiah 59:20), he died once (Romans 6:10, 1 Peter 3:18) on Earth for human sin (Hebrews 9:24–26). Intelligent extra-terrestrial beings would have been subject to the effect of the curse, as Romans 8:18–22 tells us that all of creation groans and travails under the effects of mankind’s sin. However, they would not be included in his atoning sacrifice—Jesus is the last Adam (1 Corinthians 15:45) not the last Klingon. Therefore, as we come to the end of the age, this intelligent extra-terrestrial life would be burned up (2 Peter 3:10, 12) with no hope of eternity.

First published: 10 December 2020
Re-featured on homepage: 27 April 2024

References and notes

  1. Most European scientists and philosophers had taken on Aristotle’s view that celestial bodies were unchanging, smooth, spheres, and the earth was corrupt. Although variation can be seen by looking at the moon without a telescope, these lighter and darker patches were previously explained away as density variations. Return to text.
  2. Peoples & Creatures of the Moon, loc.gov, accessed 18 Nov 2020. Return to text.
  3. Lauro, S.L. et al., Multiple subglacial water bodies below the south pole of Mars unveiled by the new MARSIS data, Nature Astronomy, 28 Sep 2020 Return to text.
  4. Mars, Venus, the 2 moons of Saturn (Enceladus & Titan), one moon of Jupiter (Europa), and the large asteroid Ceres are all still being studied in the hope to find microbial life. However, it is practically unanimous that complex multicellular life does not exist in our solar system. Return to text.
  5. One year before the idea for the JWST project started (then named; Next Generation Space Telescope) Return to text.
  6. The Nobel Prize in Physics 2019, nobelprize.org, 18 Nov 2020. Return to text.
  7. Rodriguez, J., Planet Hunters: On a quest for astronomy’s holy grail, exoplanets.nasa.gov, 7 Mar 2017. Return to text.
  8. Habitable exoplanets catalog, phl.upr.edu, accessed 20 Nov 2020 Return to text.
  9. NASA exoplanet catalog, exoplanets.nasa.gov, accessed 20 Nov 2020 Return to text.
  10. Tsiara, A. et al., Water vapour in the atmosphere of the habitable-zone eight-Earth-mass planet K2-18 b, Nature Astronomy 3:1086–1091, 11 Sep 2019. Return to text.
  11. Water found for first time on ‘potentially habitable’ planet, bbc.com/news/science-environment, accessed 20 Nov 2020 Return to text.
  12. Seife, C., Thank our lucky star, New Scientist 161(2192):17, 26 June 1999. Return to text.