In part 1 of this series, I defined the faint young Sun paradox and described how, in the 1970s and 1980s, astronomers and physicists concluded that volcanic gas emissions pumped enough extra carbon dioxide into the early Earth’s atmosphere to sufficiently enhance the atmosphere’s greenhouse effect so as to compensate for the lower solar luminosity. In part 2, I explained how research teams discovered complications that made the faint Sun paradox seem unresolvable.
Here, in part 3, I will describe how recent observations of young solar analog stars enabled astronomers to pull together everything they know about the history of the Sun, Earth, Moon, and terrestrial life to provide a real, comprehensive resolution to the paradox. This research has also yielded some of the most spectacular evidences for the supernatural, super-intelligent design of the solar system.
Not So Dim After All
Throughout the 1990s and early part of the twenty-first century, it became increasingly evident to scientists there was no way to adjust physical and chemical conditions on early Earth to compensate fully for a Sun 25–30 percent less luminous at the time of life’s origin 3.8 billion years ago. Moreover, planetary scientists were experiencing the same frustrations in their attempts to explain growing evidence that the Martian surface was, for a brief time, warm enough to permit the existence of liquid water.1
These frustrations led certain teams of astronomers to question the Sagan-Mullen model for the history of the Sun (see part 1). In 2003, Caltech astronomers Juliana Sackmann and Arnold Boothroyd pointed out that helioseismology measurements establish that, during its youth, the Sun must have lost at least 4–7 percent of its mass.2 Since the luminosity of a star rises with the fourth power of its mass, Sackmann and Boothroyd determined that the Sun’s brightness 3.8 billion years ago was 15 percent, not 30 percent, dimmer than it is today (see figure 1).
Figure 1: Sun’s Luminosity throughout Earth’s History (based on Sackmann and Boothroyd’s model)
As its nuclear furnace converted more and more hydrogen into helium, the Sun slowly recovered its lost luminosity. This brightening continues to this day and eventually will make Earth uninhabitable.
Background image: Hugh Ross
Including early mass loss in the Sun’s history goes a long way toward resolving the faint Sun paradox. With the Sun no more than 15 percent dimmer, Earth would not require nearly so great a quantity of greenhouse gases to keep the planet surface warm enough to sustain life, Thus, as Sackmann and Boothroyd note, the quantities of greenhouse gases needed are within reasonable possibility.
In support of their not-so-faint Sun model, Sackmann and Boothroyd made reference to several observational studies establishing that very young stars equivalent to the Sun’s mass are indeed losing mass at rates consistent with their model. They called for more extensive and definitive observational programs to determine the mass loss history of solar-type stars.
In the April 20, 2011 edition of Astrophysical Journal Letters three astronomers reported on the latest observations of young solar analogs.3 These stars consistently exhibit strong activity phenomena. These phenomena produce a huge variability in X-ray and ultraviolet emission, accompanied by inevitable mass loss. The three astronomers estimated that the loss of mass in the young solar analogs reaches up to 30 percent. Thus, they conclude that the Sun during its youth lost at least 20 percent of its mass. This much mass loss implies that, shortly after it formed fully, the Sun was about 85 percent brighter than it is today (see figure 2).
Figure 2: Sun’s Luminosity or Brightness throughout Earth’s History (based on Turck-Chièze, Piau, and Couvidat)
When the Sun was young, it lost at least 20 percent of its mass, enough to cause over a 100 percent loss of its light emission.
Background image: Hugh Ross
The research team then took note of the few remaining discrepancies between the standard solar model (SSM) and their observations. Specifically, sound speed determinations from helioseismology do not agree with predictions from the SSM. Likewise, there is disagreement between the observed and the predicted lithium abundance of the Sun. The three astronomers, along with other research teams,4 demonstrated that pushing the mass loss of the early Sun up from 4–7 percent to about 20 percent does much to eliminate not only these two discrepancies but a few more minor ones as well.
A Sun that loses 20–25 percent of its mass during its youth seems to solve all the outstanding issues concerning the faint Sun paradox. Evidently, the faint young Sun label needs to be replaced with a more accurate term like the “dimming young Sun.” This new model has another advantage. It explains why Mars would have been warm enough to experience a brief wet episode at some point during its first few hundred million years.5
To be clear, I am not saying the new model by itself solves all the faint Sun paradox problems. Rather, each suggested solution proposed over the past 40 years probably plays a contributing role. That is, it takes a combination of the Sun losing at least 20 percent of its mass during its first billion years, extra greenhouse gases in the atmosphere, an altered albedo for Earth, a carefully controlled and timed introduction of specific life-forms, and perhaps extra atmospheric nitrogen to explain why life could be sustained so ubiquitously and so diversely throughout the past 3.8 billion years.
The next step in building a better dimming young Sun model is to make measurements on a much larger sample of young solar analog stars. Astronomers need to make these measurements all across the electromagnetic spectrum, from gamma-ray wavelengths to long radio wavelengths. Furthermore, they need to make measurements over a few years so as to determine the short-term variability of these stars. Such observations will enable astronomers to determine precisely how much the Sun actually dimmed during its youth, over what time scale it dimmed, and whether or not the degree of dimming varies over the wavelength of solar emission.
One such observational program is already underway. A team of radio astronomers is using the Expanded Very Large Array, or EVLA, (see figure 3) to measure the interaction of stellar winds emanating from young, nearby solar analogs with the interstellar medium. With such measurements, astronomers will be able to calculate the rates of mass loss from these stars.6
Figure 3: The Expanded Very Large Array (EVLA)
Located on the Plains of San Agustin in New Mexico, the EVLA consists of antennas 27–25 meters diameter. With upgraded receivers, electronics, and processors the array will deliver a dramatic increase in sensitivity, wavelength coverage, and imaging capability.
Image credit: The National Radio Astronomy Observatory
The new model does place a new constraint on origin-of-life models. A much-brighter young Sun is a Sun with more dramatic flaring activity, greater variability, and greater X-ray and ultraviolet radiation emission. These features, combined with a rapidly falling solar luminosity, effectively rule out any possibility for life existing on Earth previous to the late heavy bombardment (see here and here). The date for the late heavy bombardment’s end, 3.8 billion years ago, is the same for the first evidence of Earth life; that means the origin of life took place within a geological instant of time. No time for life’s origin implies there’s no possibility for a naturalistic explanation.
As King David declared 3,000 years ago, “The earth is the Lord’s, and everything in it.”7 The new dimming young Sun model proves David’s declaration in a broader context. Sustaining abundant, diverse life throughout the past 3.8 billion years requires multifaceted fine-tuning. As the Sun’s luminosity dims or brightens, certain features on Earth must be fine-tuned correspondingly.
1. The amount of carbon dioxide in Earth’s atmosphere
2. The amount of methane in Earth’s atmosphere
3. The amount of nitrogen in Earth’s atmosphere
4. Earth’s albedo
5. The quantity and diversity of Earth’s life to contribute or remove just-right amounts of greenhouse gases, erosion, and albedo
No set of natural processes can possibly keep all these factors perfectly and continuously balanced for billions of years. It takes a Mind of great intellect and knowledge who knows the solar system’s present and future conditions and who has the power and the love to provide Earth’s life with everything it needs to thrive.
This article is Part 3 (of 3) of "Resolving Faint Sun Paradoxes".
To access additional parts, please click on the links below: