Today’s New Reason To Believe

Previously published on December 10th, 2007 by Hugh Ross

A team of American astronomers recently announced the discovery of the first known planet outside our solar system to spend its entire orbit within the “habitable zone.”¹ When astronomers talk about a habitable zone for a planet they simply mean that the planet is orbiting within that distance from its star where surface liquid water would be possible—assuming the atmosphere of the planet is fine-tuned so as to trap the just right amount of heat from the planet’s star.

The newly discovered planet, 55 Cancri f, orbits the star 55 Cancri and weighs in at 45 times the mass of Earth, making it a gas giant. All astronomers recognize that the dense atmosphere that such a planet must possess precludes any possibility of habitation. However, as Debra Fischer, leader of the research team, explained to reporters, “The gas giant planets in our solar system all have large moons. If there is a moon orbiting this new, massive planet, it might have pools of liquid water on a rocky surface.” ²

The characteristics of 55 Cancri and four known planets orbiting it rule out the possibility of life anywhere within the 55 Cancri planetary system. I discussed these hostile conditions on the November 10, 2007, Reasons To Believe Science News Flash. A more general discussion centers on whether or not moons for any planetary system make realistic candidates for life.

As Fischer says, all the gas giant planets in the solar system possess large moons. Compared to the mass of Earth, the largest moons for each of the solar system’s gas giants are: Jupiter’s at 2.48%, Saturn’s at 2.25%, Neptune’s at 0.36%, and Uranus’ at 0.06%. Earth’s moon weighs in at 1.23%

However, life requires a strong, stable magnetic field to protect the moon from the charged particles emanating from the star that would otherwise sputter away the moon’s atmosphere. Life also needs strong, stable plate tectonics to contribute to the necessary mechanisms for compensating for the star’s increasing luminosity over its burning history. Unless the moon’s mass exceeds 23 percent of Earth’s mass, plate tectonics and a strong magnetic field are impossible. For such necessities to last for a few billion years requires a mass and a density virtually equivalent to Earth’s.³ Thus, the solar system’s largest moons fall short by a factor of forty or more from being large enough for life.

The orbital zone where surface liquid water could theoretically exist on some rocky body is relatively broad if one adjusts the atmosphere to compensate. For example, Earth’s orbit could be pushed out to a little more than halfway beyond the mid-point between Earth’s and Mars’ present orbits and still sustain surface liquid water—if greenhouse gases saturated Earth’s atmosphere. Removing all of Earth’s greenhouse gases would allow liquid water to persist on Earth even if it were situated 10 percent closer to Venus’ orbit than it is now. But, a liquid water zone does not equate to a truly habitable zone. Without adequate greenhouse gases, life—at least life more advanced than bacteria—dies. Conversely, overly plentiful greenhouse gases would cripple the operations of breathing organs like lungs. Therefore, existence of plants and animals demands a much narrower zone than what astronomers refer to as “the habitable zone.”

Actually, for any given planet or moon the true habitable zone would be far more narrow yet. If Earth’s orbit moved about a half percent farther from the Sun, Earth’s surface would experience a runaway freeze. Cooler temperatures caused by the greater distance from the Sun would result in more snowfall. Since snow reflects sunlight more effectively than soil, greater snow cover causes Earth’s surface temperature to drop even more, which results in still more snow falling and an even greater drop in temperature until all of Earth’s surface freezes over.

On the other hand, if Earth’s orbit moved about a half percent closer to the Sun, Earth’s surface would experience a runaway evaporation of water. This happens because the closer distance to the Sun yields a higher surface temperature on Earth that causes more water to evaporate. Water vapor is a greenhouse gas. Thus, more water in Earth’s atmosphere causes the surface temperature to rise, which results in more evaporation. The cycle continues until all of Earth’s water evaporates.

If the moon orbits too close to its planet it becomes tidally locked, culminating in one side of the moon perpetually facing the planet. Typically, this causes long cold nights and long hot days. Such a close-in orbit would also generate destructive tides and volcanic eruptions; and if the planet possesses a strong magnetic field, its magnetosphere could wreck havoc on the moon’s atmospheric layers. Orbiting too far away from its planet causes a moon to experience enormous seasonal temperature differences as its journey about the planet puts it alternately closer and farther away from its star.

Close-in or far-out, a large moon orbiting a large gas giant planet would experience heavy bombardment from comets and asteroids. Just as the gravity of Jupiter attracts a lot of asteroids and comets to veer into its vicinity, so, too, the gravity of large gas giant planets implies that any big moon orbiting them will receive a lot of life-catastrophic collisions.

Even moons with interior ice-water environments heated through tidal friction from the planet’s gravity (such as may be the case for Jupiter’s moon Europa) also provide poor long-term life sites. Without a carbonate-silicate cycle, such a moon cannot properly compensate for the star’s increasing luminosity. However, this cycle will not operate without plenty of dry land exposed to a specific atmosphere where that dry land contains particular kinds and quantities of life.

With such a narrow true habitable zone, life on a moon becomes especially problematic. More reasons than the few described here rule out moons as potential life sites for any kind of long-term plant and animal life.⁴ Since the discovery of the first extra-solar planet in 1995, astronomers have cataloged 265 extra-solar planets. All these planets have taught us much about the formation and dynamics of planetary systems. The record of the past twelve years shows that the more astronomers learn about the characteristics of planets, moons, and their stars, the more evidence they uncover for the exceptional rarity of the solar system’s conditions that permit the existence of life. The case for the supernatural design of the human-friendly Milky Way Galaxy and solar system continues to build.

1. Ian Sample, “Could This Be Earth’s New Twin? Introducing Planet 55 Cancri f,” The Guardian (Wednesday, November 7, 2007).
2. Ian Sample, The Guardian (Wednesday, November 7, 2007);
3. Diana Valencia, Richard J. O’Connell, and Dimitar D. Sasselov, “Inevitability of Plate Tectonics on Super Earths, “Astrophysical Journal Letters,” 670 (2007): L45-L48.
4. Hugh Ross, Kenneth Samples, and Mark Clark, Lights in the Sky and Little Green Men (Colorado Springs, CO: NavPress, 2002): 39-41.

Posted by Fazale ‘Fuz’ Rana, Ph.D.

New Research Indicates Early Earth Conditions Were Too Harsh for Life’s Origin

Since the onset of the Industrial Revolution, acid rain has been an environmental problem. Industrial processes introduce sulfur and nitrogen oxides into the atmosphere. These gases react with water to form sulfuric and nitric acids, respectively.

Acid rain causes damage by chemically altering soils and surface waters-harming aquatic life and vegetation. It even corrodes historical monuments and buildings.

According to new research, it appears that acid rain was also a problem quite early in Earth’s history.* Geologists think that this acid rain accelerated the weathering of the early Earth’s crust and would have likely frustrated evolutionary processes needed for the origin of life.

Some background information helps give context to this discovery.

Early Earth Conditions: The Standard View

Generally speaking, geologists have believed that shortly after the earth formed, it existed primarily in a molten state. Most would maintain that neither a permanent crust nor permanent oceans existed on the planet. In these conditions, large amounts of heat would have been liberated from the decay of high levels of radioactive isotopes present on early Earth, rendering the surface a magma ocean. Impact events would have also melted rock on the surface and sub-surface of the planet, vaporizing bodies of liquid water.

Presumably, these conditions persisted from the time of Earth’s formation (about 4.6 billion years ago) until about 3.8 billion years ago. This part of Earth’s history is referred to as the Hadean Era, after Hades, the Greek word for hell.

The Late Heavy Bombardment

Near the end of the Hadean Era, an event known as the Late Heavy Bombardment took place. Asteroids (and maybe comets) pummeled the solar system’s inner planets and moons. Estimates indicate the Earth experienced over 20,000 impact events, with significant environmental damage occurring every 100 years or so.

Once the Late Heavy Bombardment came to an end, the earth developed a permanent crust and liquid water oceans became enduring features.

Early Earth and the Origin of Life

Because of the hellish conditions that existed on the planet, most origin-of-life researchers can’t envision how life could arise, let alone persist, during the Hadean Era or the Late Heavy Bombardment. This conviction raises some troubling questions, since life suddenly appears on Earth at about 3.8 billion years ago, “coincidentally” at the tail end of the Late Heavy Bombardment. (See the book Hugh Ross and I coauthored, Origins of Life for a detailed discussion of the evidence that demonstrates a sudden and early appearance of life on Earth.)

Early Earth Conditions: A New Paradigm?

The standard view of early Earth is being challenged by pieces of zircon recovered from rock formations in western Australia. These minerals date to about 4.2 to 4.4 billion years in age, making them the oldest materials on Earth! Zircon is an extremely hard material with a high melting point and could readily survive the tumult of the Late Heavy Bombardment. These ancient minerals provide an unprecedented opportunity to peer into the time before the Late Heavy Bombardment.

Analysis of isotopes present within the zircons suggests that water oceans and a crust may have existed on Earth, during the Hadean Era, prior to the Late Heavy Bombardment. Other studies support this conclusion. (Go here for a recent example.)

The discovery of more benign conditions on early Earth leaves open the possibility that life may have originated gradually over the course of several hundred million years, instead of immediately after the Late Heavy Bombardment. (Even if life did originate prior to 3.8 billion years ago, it’s difficult to envision how it could have survived the Late Heavy Bombardment.)

New insight into the conditions of early Earth, gleaned from the zircon crystals, turns out to be corrosive to these naturalistic hopes.

Acid Rain on Early Earth

Analysis of lithium isotopes in the ancient zircons indicates that the crust of the early earth experienced extensive weathering most likely from acid rain.

These harsh conditions would have frustrated the origin-of-life process. Even though microbes, called acidophiles, can live under highly acidic conditions, it’s unlikely that they could have originated under those conditions. Acidic conditions inhibit key prebiotic reactions like the Strecker synthesis, the formose reaction, and hydrogen cyanide polymerization. Acidic conditions also promote the breakdown of key biomolecules like proteins and DNA.

The revised insights into the Hadean Era are radically changing our understanding of Earth’s infancy. At the same time this evidence is doing little to facilitate evolutionary explanations for the origin of life. Hopes for a naturalistic explanation for life’s beginnings are slowly dissolving like an icon exposed to the steady pelt of acid rain.

*This study made science news headlines when first published. I discussed the scientific and biblical implications of this research on the June 24, 2008 edition of our podcast, RTB’s Science News Flash. This podcast offers a unique Christian perspective on headline-grabbing discoveries. A free subscription is available through iTunes.

by Jeff Zweerink

In April 2008, the fifth Astrobiology Science Conference convened in Santa Clara, California. According to its mission statement, the SETI Institute, which hosts these conferences, seeks to “explore, understand and explain the origin, nature and prevalence of life in the universe.”

One of the sessions at the conference focused on how the habitability of the galaxy varied in space and time. Two of the talks in that session each highlighted an issue important for human life here on Earth. The first talk, by Australian astronomer Charles Lineweaver describes the regions of the galaxy meeting three requirements for life (from strictly natural processes):

1. enough elements to form terrestrial planets,
2. sufficient time for biological evolution, and
3. an environment free from life-extinguishing supernovae.

This galactic habitable zone is an annulus (ring) around the galactic center that brackets the corotation radius. At this radius, stars orbit the galaxy at the same speed as the spiral arms, thus minimizing passages through the spiral arms. According to Lineweaver&’s calculations, his galactic habitable zone contains less than 10 percent of all the stars ever formed in the Milky Way Galaxy.

Another talk, by Kansas University astronomer Adrian Melott, described a 62-million-year periodicity (cycle of increase and decrease) in the level of biodiversity seen in the fossil record. His research argues that the passage of the sun through the galactic plane—which increases the comet and asteroid bombardment in the solar system—as the cause of the periodicity. If correct, the habitability of a star&’s planets depends not only on its location but also on its path through the galaxy. Since the sun oscillates through the galactic plane every 30 - 35 million years, the solar system would now be starting a passage through the galactic plane, thus beginning a period of increased bombardment (and possible extinction).

Both of these papers, as well as many others presented at the conference, articulate the many factors that must exist simultaneously for a planet to be suitable for advanced life like humans to exist. Such research continues to demonstrate the scientific reasonableness of believing that a supernatural Creator fashioned and designed Earth as a unique habitat for human life.