The young faint Sun paradox and the age of the solar system
by Danny Faulkner
According to theory, the Sun derives energy by the thermonuclear conversion of hydrogen
into helium, deep inside its core. There is convincing evidence that the Sun is
getting at least half of its energy by this method. Such a thermonuclear source
could power the Sun for nearly 10 billion years. Most scientists think that the
Sun (along with the rest of the solar system) is about 4.6 billion years old, which
means it would have exhausted approximately half its ‘life’.
NASA
The Sun. As the Sun ages, it increases in brightness and produces more heat. If the Sun is as old as claimed by mainstream scientists, 3.8 billion years ago the Earth would have had an average temperature of -3°C.
Over the Sun’s lifetime, the thermonuclear reactions would, according to theory,
gradually change the composition of the core of the Sun and alter the Sun’s
overall physical structure. Because of this process, the Sun would gradually grow
brighter with age. Thus, if the Sun is indeed 4.6 billion years old, it should have
brightened by nearly 40% over this time.1
Evolutionists maintain that life appeared on the Earth around 3.8 billion years
ago. Since then, the Sun would have brightened about 25%,2
though there is some uncertainty in that figure.3
This would appear to present a temperature problem for the evolution of life and
the Earth. With the current hand-wringing over global warming, one would expect
that such a large difference in the solar output would have greatly increased the
Earth’s temperature over billions of years. Yet most biologists and geologists
believe that the Earth has experienced a nearly constant average temperature over
the past 4.6 billion years, with perhaps warmer conditions prevailing early on.4 The problem of how the Sun could
have increased in brightness while the Earth maintained a constant temperature is
called the ‘early faint Sun paradox’.
Just how great is the problem? A simple calculation can be made assuming that, over
time, there has been no change in the Earth’s reflectivity or the ability
of the Earth to radiate heat. While this approach is almost certainly unrealistic,
it is useful to illustrate the problem. With these assumptions, we find that a 25%
increase in solar luminosity increases the average temperature of the Earth by about
18°C. Since the current average temperature of the Earth is 15°C, the average
temperature of the Earth 3.8 billion years ago would have been below freezing (-3°C).
Thus when life supposedly was just beginning, much of the Earth would have been
frozen.
Even with such a low average temperature some tropical portions of the Earth may
have remained ice-free. Naturally, evolutionists could argue that life developed
in the warmer areas and then held on until the Earth warmed. However, there are
at least two problems with this.
-
Most geologists seem to insist that over the past 3.8 billion years the average
temperature of the Earth has not changed that much. If anything, temperatures before
2.5 billion years ago would have been warmer.
-
If the Earth had ever been mostly covered with ice year round, then its average
temperature would have been even cooler than the -3°C mentioned above. The increased
ice cover would increase the reflectivity of the Earth, reducing the heat absorbed
from the Sun. This is a common problem with the popular idea of multiple ice ages—once
one commences in earnest, the increased reflectivity due to additional ice cover
leads to decreased solar heat absorption that is difficult to reverse toward a warmer
climate. (The Oard model of a single post-Flood Ice Age caused by warm oceans and
volcanic dust in the atmosphere does not have this problem.5
As the volcanic dust eventually dissipated, the oceans provided the heat to melt
back much of the ice cover.)
How do evolutionists resolve the early faint Sun paradox? Most assume that the early
atmosphere of the Earth had more greenhouse gases than the current atmosphere. This
would have kept the Earth warm despite the Sun being less luminous at the time.
As the Sun increased in brightness, the amount of greenhouse gases in the atmosphere
is supposed to have decreased in such a way as to exactly cancel the increased heat
received from the Sun. In other words, as the Sun evolved, the Earth’s atmosphere
also evolved to cancel out the effect of the increased solar luminosity. The evolution
of life is supposed to have played a role in this evolution of the atmosphere.
Clearly, such evolution of the Earth’s atmosphere would require a very delicate
balancing act. While there is some tolerance for deviation, any prolonged deviation
from ideal conditions could have led to catastrophic heating or cooling from which
the Earth might not have recovered. Venus and Mars are possibly examples of each
of these scenarios.
Planetary scientists think that while the Earth and Venus are very similar, Venus’
closer proximity to the sun gave that planet an initial temperature higher than
that of the Earth that led to a runaway greenhouse effect. As a result, today Venus
has the hottest surface temperature in the solar system. Conversely, Mars is a very
cold planet today, yet there is abundant evidence that, early in its history, liquid
water once flowed on its surface, indicating that Mars was much warmer. Most researchers
say this happened about 3.8 billion years ago. However, at that time the Sun would
have been 25% fainter than today. Therefore, the early faint Sun paradox provides
a very different problem for Mars: why was that planet much warmer when the Sun
was at its faintest?
With the obviously disastrous results on our nearest planetary neighbours, how did
the Earth avoid a similar fate? How did the Earth’s atmosphere manage to evolve
in such a delicate fashion? One possibility is that it just happened that way. The
geological and biological processes removed greenhouse gases at exactly the same
average rate to compensate for the increased solar luminosity. What would be the
probability of this happening by chance?
Because the evolution of such a delicate balance is so improbable, some have suggested
that the Earth’s biosphere behaves as a giant single organism. This pantheistic
idea, seriously proposed by scientist James Lovelock, has been dubbed the Gaia hypothesis,
after the goddess of the Earth. Repelled by the teleological connotations, many
scientists reject the Gaia hypothesis, opting for the appeal to chance.
Of course, another logical possibility is that the solar system is only thousands
of years old. In this case, there is no paradox to explain because the Sun has not
been around long enough to increase much in luminosity. Many may object that we
know that the Sun is 4.6 billion years old, but that is not true. There is no direct
way of measuring the age of the Sun. Our understanding of the Sun’s structure
does not permit a precise calculation of how bright a ‘zero age’ Sun
should be compared with a 4.6-billion-year-old Sun. All that we can conclude is
that the older Sun should be brighter than the younger Sun. The 4.6-billion-year
age comes from the alleged age of meteorites, and it is assumed that the Sun is
the same age. Of course creationists reject the billion-year age for meteorites
as well.
So, the early faint Sun paradox is evidence that the Sun, and therefore the solar
system, is young and consistent with the 6,000-year age of the solar system as recorded
by Biblical chronology.
Related articles
Further reading
References
- Faulkner, D.R., The young faint Sun paradox and the age of the solar system, Impact (ICR) 300,
1980. Return to text.
- Lenton, T.M., Gaia and natural selection, Nature
394(6692):439–447, 1998. Return to text.
- Sagan, C. and Chyba, C., The early faint Sun paradox: organic shielding
of ultraviolet-labile greenhouse gases, Science 276(5316):1217–1221,
1997. Return to text.
- Sagan and Chyba, Ref. 3 and references 13, 14, 17, 18, and 19 cited
therein. Return to text.
- Oard, M.J.,
An Ice Age Caused by the Genesis Flood, Institute for Creation Research,
El Cajon, CA, 1990. Return to text.
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