Today’s New Reason To Believe

Previously Posted on Jan 11th, 2008 by David H. Rogstad, Ph.D.

In the television series Cosmos: A Personal Voyage, originally broadcast in 1980, Carl Sagan, the highly successful popularizer of astronomy, coined the phrase “we are made of star-stuff.” While not a new idea, nevertheless, it called attention to a remarkable fact related to our growing understanding of how the universe began and developed over time.

Dr. Sagan outlined this process, beginning with the Big Bang, where the lightest elements, hydrogen and helium, were produced. He then proceeded to describe the various generations of stars that were formed, aged, and eventually “went supernova,” finally coming down to the formation of our solar system made from the ashes of these earlier stars. The end result is that humans, who are made from “the dust of the Earth,” originally came from material that was “cooked” from lighter elements in the very heart of stars and their subsequent supernova.

With NASA’s 1999 launch of the Chandra X-ray Observatory into orbit around the Earth astronomers have been able to use this new tool to detect many different objects in a band of light beyond what’s visible to human eyes, and at a much higher resolution than previously available. A recent press release revealed a spectacular new image of the supernova remnant G292.0+1.8. A supernova remnant is the expanding debris field blasted out from the parent star as it explodes. G292.0+1.8, which contains large amounts of oxygen, is one of only three remnants in our Milky Way Galaxy. The image shows an intricate structure in its debris field that contains element such as oxygen, neon, and silicon that forged before and during the explosion.

Understanding the details of G292.0+1.8 is especially important because astronomers have considered it to be a “textbook” case of a supernova created by the death of a massive star. Supernova events such as this have been determined to occur in the neighborhood of our solar system prior to its collapse, seeding the cloud out of which the Earth formed with elements critical for life (see the 23 January 2007 edition of Today’s New Reason To Believe ).

With instruments like the Chandra telescope, astronomers are developing a deeper understanding of the processes that clarify in detail Sagan’s observation that we are made from material that originated in stars. At the same time, the evidence supports the fine-tuning necessary for the “star-stuff” to have just the right amounts of the various elements to allow life to exist and survive. Not only do we have spectacular images of the “stuff,” which “declare the glory of God,” but we also have better understanding of the processes for making that stuff that reflects the hand of an elegant designer.

by Hugh Ross

It is now obvious to all planetary scientists that Earth possesses many apparently designed features that have enabled it to support life for billions of years, and to support advanced life in particular. As I described in last week’s Today’s New Reasons To Believe, two MIT planetary scientists added to the list of these features. Their modeling of the formation history of planets the size of, and larger than, Earth led to this conclusion: barring any subsequent extraordinary collision events, such planets will end up with at least a hundred times more water and carbon than what our home planet presently contains.¹ Earth’s extreme lack of water and carbon makes possible its thin atmosphere and exposed continental landmasses—both essential features for advanced life.

Now, the same two scientists have extended their modeling of terrestrial planets (rocky, Earth-like planets) to test whether or not the pervasive assumption that all such planets will form a metallic core is really correct.² This assumption arises from the fact that all the rocky planets in the solar system possess metallic iron-dominated cores. These cores developed very early in the formation of the solar system. Driven by the heat arising from the kinetic energy of accretion (growth), the melting of the metal and silicate portion of the planet caused the denser metallic iron to fall toward the planet’s core.

The reseachers suggest two different accretionary paths for the formation of a rocky planet that produces a coreless planet. In the first case, the planet forms from material in the star’s protoplanetary disk that is already fully oxidized before the accretion process begins. Support for this proposal comes from the existence of chondrite meteorites (the remnants of the solar system’s protoplanetary disk) that contain no metallic iron but rather iron oxides bound into silicate mineral crystals. Cooler accretion temperatures caused by either a later planetary accretion time, or a planetary accretion more distant from its star or about a cooler star would favor this scenario.

In the second case, the planet forms from both water-rich and metal-rich material. (Protoplanetary material contains three dominant components: water, silicate rock, and iron metal.) Instead of sinking into the core, the metal iron reacts with the water to form iron oxides. This oxidized iron becomes trapped in the mantle, unable to form a core. The planet will end up coreless, providing the oxidation rate for the iron is faster than the sinking of metallic iron to form a core.

The planet formation pathways the MIT team describe appear to be just as likely, perhaps even more, than the means by which the solar system’s array of rocky planets formed. One way to find out for sure would be to measure the density of rocky planets orbiting other stars. A planet with a metallic core will exhibit a higher density than a planet without such a core. Further, the larger the metallic core relative to the remainder of the planet, the higher the density. Earth with its huge metallic core manifests an extremely high density (even more remarkable given how far away Earth is from the Sun).

Calculating the density of extrasolar planets requires measurements of the planet crossing in front of the image of its star (or transit measures). Such measures provide the diameter of the planet, which when combined with the mass determinations that arise from calculating the planet’s orbital parameters, yield its density. (Density = mass divided by volume.)

So far, astronomers lack the instrumental power necessary to accurately measure the diameters of extrasolar planets (see here and here) as small as Earth. However, such instrumental power is soon to arrive. Then, astronomers will be able to test the conclusions of the MIT team.

No one can argue, however, that the researchers’ conclusions are unreasonable. No longer can astronomers presume that all rocky planets possess metallic cores and certainly not metallic cores as enormous as Earth’s.

Earth is only the second densest planet in the solar system. Mercury is slightly denser. However, Earth’s density is truly gigantic when one considers both its mass and its distance from the Sun. The more massive a protoplanet, the stronger will be its gravitational capacity to accrete lightweight material from the protoplanetary disk. The more distant a protoplanet from its star the cooler will be the protoplanetary disk material in its immediate vicinity. Cooler temperatures permit the accretion of lighter-weight material.

The table below shows just how outstanding the Earth is among all the Sun’s rocky planets. For each planet its density is multiplied by its distance squared from the Sun (relative to Earth’s distance) and by its mass (relative to Earth’s mass).

- Mercury 0.048
- Venus 2.176
- Earth 5.517
- Mars 1.033

No accretion pathway exists by which Earth could have ended up with such a high density and huge metallic core. It attained these features thanks to an exquisitely designed collision event early in its history, an event that also led to the formation of the Moon.³

Our planet’s gigantic metallic core is just one of many features that must be fined tuned in order for it to sustain advanced life. Without this particular core, Earth could not maintain a long lasting, powerful dynamo in its core. It is this dynamo that is responsible for the strong, enduring magnetic field that so ably protects advanced life on Earth from deadly solar and cosmic radiation.

As the MIT team’s analysis demonstrates, the more we learn about the physics of extrasolar planetary systems, the more evidence we accumulate for the supernatural, super-intelligent design of the Milky Way Galaxy, the solar system, and Earth for the benefit of all life, both simple and complex.

1. Linda T. Elkins-Tanton and Sara Seager, “Ranges of Atmospheric Mass and Composition of Super-Earth Exoplanets,” Astrophysical Journal 685 (October 1, 2008): 1237-46.
2. Linda T. Elkins-Tanton and Sara Seager, “Coreless Terrestrial Exoplanets,” Astrophysical Journal 685 (November 20, 2008): 628-35.
3. Hugh Ross, Creation As Science (Colorado Springs: NavPress, 2006), 111-15.

by Jeff Zweerink

My first experience with publishing recently culminated with the release of Who’s Afraid of the Multiverse? The process required numerous editors inspecting my writing, making improvements, and checking for errors. The first editorial passes put the basic structure of the booklet in place and made sure the “plot” developed well. Ensuing phases verified that each section communicated its message clearly and transitioned into neighboring sections. The last stages checked for any typographical and grammatical errors. A quality publication requires that each step proceed in the proper order and build on previous steps.

The development of scientific models operates in a similar fashion. The model must first explain the big picture. Then the model is filled out with predictions and newly gathered data, providing more and more detail. For example, inflationary big bang cosmology provides the best explanation for many of the big picture aspects of this universe. Two notable examples include the observed redshifts of distant galaxies and the uniformity (and important small clumps) of the cosmic microwave background (CMB) radiation. However, there remain many outstanding issues remain in big bang cosmology. How did the first stars form and what did they look like? What was the mechanism that caused the inflationary epoch? How did the magnetic fields of galaxies arise? Some would argue that such unanswered questions invalidate big bang cosmology.

Most scientists look upon such unanswered questions as exciting areas of future research. In fact, such an attitude recently led to results that provide at least part of the answer to how the first stars formed.

Two competing processes affect star formation. Gravity causes material to clump together tightly enough to allow nuclear fusion to ignite in the heart of the newly-formed star. But the energy given off as the material collapses wants to push the outer material away from the star, preventing the star’s formation. Unless the star can radiate this energy away efficiently, the blob of gas remains too large (in physical size) for a star to form. For stars like the Sun, elements heavier than helium provide this cooling mechanism. However, after the big bang, only the earliest elements hydrogen and helium existed (practically speaking) so it seems that it would be impossible for such a mechanism to function.

A team of Japanese and American scientists performed a detailed simulation of the early universe when the first stars formed. The simulations demonstrated that the primeval density fluctuations (those imprinted on the CMB radiation) could generate protostars (developing stars) with masses one percent the mass of the Sun. These results validate one of the vital first steps in forming the first stars. The team expects that future research will demonstrate how these protostars can accrete (collect) hydrogen from the surrounding gas. After growing to masses around 100 times the mass of the Sun, these stars would burn quickly and explode—sending out heavier elements that enabled future generations of smaller stars to form.

Solving this critical first step is like the editor ensuring that one important booklet section transitions properly to the next section.

Every scientific model contains unresolved problems. However, RTB’s creation model, which incorporates big bang cosmology, stands as a successful one where problems diminish with future research. In fact, research into these obstacles has led to a greater understanding of the processes God used to create and develop this universe.