Many evolutionists have long hoped to find evidence of life in space. They reason
that if life evolved on Earth, then it could have evolved elsewhere.1
If, as the argument goes, there are countless planets throughout the universe that
have formed via natural processes, there must be other Earth-like planets. Many
think that finding such a planet outside our solar system would be almost like finding
evidence of life in space.
Scientists have searched for years for planets orbiting other stars. These are called
extrasolar planets, or ‘exoplanets’. Astronomers first obtained evidence
suggesting extrasolar planets around 1995 while studying the sun-sized star 51-Pegasi.2 Today there are research teams
around the world searching for extrasolar planets with greatly refined research
techniques. There are now over 450 objects catalogued in exoplanet lists.3,4
Biblical perspective
Creationists need to answer two main questions regarding exoplanets. 1) Do they
exist? and 2) How did they form? The first question has to do with experimental
evidence, but the second has to do with origins science. Scripture does not tell
us whether other stars have planets, so we must apply the best observational science
we can to answer the question.
On the other hand, Scripture is clear that God supernaturally created the earth
and the universe in four consecutive, normal-length days and that the universe is
relatively young.5 Thus,
if the observational evidence for exoplanets is sound, which I believe it is (see
box), creationists will differ with secular scientists about
how and when they formed, not whether they exist.
The Origin of Exoplanets
As scientists came to the conclusion that extrasolar planets exist, they faced challenges
in explaining their origin. From a creation point of view, it is most likely that
God created exoplanets on Day 4 of Creation Week, along with the luminaries, and
He could have created them with any characteristics He wished. Our own solar system
is special because of Earth—our system and our planet are designed to be a
safe and stable environment for life. Isaiah 45:18 acknowledges this, “He did not create
it [Earth] to be empty; he formed it to be inhabited.”
Exoplanets: enemy of evolution
There are significant scientific problems with attempts to explain the formation
of stars and planets from clouds of gas and dust.6,7 One main issue
is that the hypothetical disk of gas and dust tends to dissipate too fast for the
resulting planets to become as large as they are observed to be. There are other
major problems:
Migrating planets
Many extrasolar planets orbit extremely close to their stars—even closer than
Mercury is to the sun. Thus they are far too hot for many materials to condense
and pull together by gravity. A few exoplanets even lose matter to the star or from
their gases being essentially “boiled away”.
To address this problem, evolutionary astronomers proposed that planets could form
far away from the star and then the orbit could move inward. This is referred to
as orbit migration. This would allow the planets to form in a cooler region
of their stellar system, but then the orbit would shrink, due to friction from the
dust disk slowing the planet, to put the planet where we see it now.
The idea can also be applied in other ways. For example, in our own solar system,
astronomers realize that there would have been too little material at the distance
of Uranus and Neptune to form these giants, so they proposed that they formed closer
to our sun, then migrated outward to their current orbits.8
Orbit migration theories have difficulties because the dust disk around the star
tends to dissipate before the planet can grow large enough or before it can come
to its observed position.9
Reversed and slanted orbits
A new problem for planet origin theories has surfaced in recent months. A technique
has been developed to determine a planet’s orbital tilt relative to the equator
of the star. Several exoplanets actually have retrograde orbits10—in the opposite direction of the star’s
spin. Other exoplanets have very large orbital inclinations (slants), some more
than 80 degrees.
These strange orbits create a serious problem for planet origins models because
a planet is said to get the momentum for its orbit from the dust disk that it formed
from. Thus planet orbits should initially be in the same plane as the equator of
the star, and in the same direction as the star’s rotation. But there is no
plausible way that a dust disk can give rise to a planet with an orbital tilt of
80 degrees, let alone a reverse direction orbit.
Evolutionary planetary scientists are generally trying to answer this by assuming
that where the planet orbit is highly inclined or retrograde, there was once one
or more other planets (or possibly stars) in the stellar system that were also at
highly inclined orbits. If there are multiple objects (stars or planets) in various
highly inclined orbits, then this could possibly cause some complex orbit changes.11 Some scientists believe
that where there are three or more stars and planets in a system, it is possible
for a planet’s orbit to become highly inclined. But this must assume that
objects once existed in these systems at large distances from their star, which
we cannot or do not observe (and where did they come from?). It is also questionable
that this highly unlikely process could happen for all the known cases of retrograde
planets.
Implications
Certainly extrasolar planetary systems differ from our solar system. They show that
God created variety in the universe and that our own planet was created with design
and purpose. Astronomers are getting closer to being able to detect an Earth-sized
planet. But we must not confuse an Earth-sized planet as being a truly
Earth-like planet. It is no accident that Earth is in the so-called “habitable
zone” in our solar system—a narrow range of distances from the sun where
liquid water can exist.
No known extrasolar planets are considered habitable—lifeless Venus and Mars are more ‘Earth-like’. In
fact, even if a planet very much like Earth were eventually discovered, with an
appropriate atmosphere and liquid water, that does not in and of itself mean that
life could evolve on such a planet. We depend on our Creator for the planet we have
and to create and sustain life.
Astronomers measure very precisely the spectrum of the star’s light. An extrasolar
planet can cause a periodic change in the motion of the star as it orbits, essentially
making the star wobble and causing tiny variations in the colour of the light,13 due to the Doppler effect.14 If a planet is more
massive or it is close to the star, then it causes a larger “wobble”
on the star than if it were smaller or farther away. Planets that are farther away
from their stars cause slower wobbles because the planets orbit more slowly.15 Astronomers have used this
technique to discover many exoplanets and sometimes multiple planets. But while
the Doppler method can estimate a planet’s mass and distance from its star,
it can’t tell us the planet’s composition.
2. Transit or photometric method
This measures the slight drop in a star’s brightness as a planet passes in
front of it. This won’t work for most stars, because the planet must block
Earth’s line of sight. (Transit measurements have revealed exoplanets orbiting
about 100 stars.) The silhouette of a planet transiting a star gives the planet’s
size and the star’s light skirting the planet can indicate the composition
of any atmosphere.
Many of the exoplanets studied this way seem to be large gaseous planets like Jupiter
or Saturn in our own solar system. Combining a planet’s diameter with the
estimate its mass gives its density. There is at least one known case of an exoplanet
that has a similar density to Earth.16
A significant portion of this planet’s mass must be rock.
If the transit dimming of a star is in time with wobbling, this is especially strong
evidence for a planet.
3. Direct imaging
In recent years, telescopes have been launched into space to obtain photographs
of extrasolar planets as they orbit their stars. In 2009, NASA launched the Kepler
Mission, a space observatory designed for very precise transit measurements of extrasolar
planets.
One photographed exoplanet orbits a nearby star called Fomalhaut. Called Fomalhaut
b, it orbits just inside a dust ring.17
The Hubble Space Telescope took photos over two years, showing that this object
was in motion around the star. The Spitzer Space Telescope has also detected infrared
radiation from two hot Jupiter-like exoplanets.18
Direct imaging is likely to discover more exoplanets, and to verify claims from
the other methods.
Spencer, W., The Origin and History of the Solar System,
in: Walsh, R.E., ed., Proceedings of the Third International Conference on
Creationism, pp 513–523, Creation Science Fellowship, Inc., Pittsburgh,
PA, 1994. Return to text.
For example, for one exoplanet, WASP-18b, estimates suggest
the planet should have fallen into the star in about 650,000 years after formation,
much less than the presumed evolutionary age of billions of years.
Another problem is, how could the dust disk last long enough to move the planet
several Astronomical Units from the cold region where it formed to close to the
star where it is observed today? See Spencer, W.,
The search for Earth-like planets, Journal of Creation24(1):72–76,
2010. Return to text.
Turning Planetary Theory Upside Down, Royal Astronomical
Society, 13 April 2010; www.ras.org.uk. Return to text.
Fabrycky, D. and Tremaine, S., Shrinking binary and planetary
orbits by Kozai Cycles with tidal friction, Astrophysical Journal 669(2):669–1298,
2007 | doi: 10.1086/521702. Return to text.
Kalas, P., Dusty disks and planet mania, Science281(5374):182–183, 10 July 1998; Planet mania, Creation21(1):7, 1998. Return to text.
When the star is moving towards us, the light is ‘blue-shifted’,
i.e. to a shorter wavelength, and when it’s moving away, we see a ‘red
shift’. Return to text.
This may seem difficult to believe, but our own Sun actually
wobbles as it moves through space as well, due to the gravitational pull of Jupiter
and the other planets. Boss, Alan, Looking for Earths: The Race to Find New Solar
Systems, pp 8–9, John Wiley & Sons, Inc., New York, 1998.
Return to text.
The creationist astronomer Johannes Kepler
(1571–1630) discovered that the square of the planet’s period is proportional
to the cube of its distance from the sun, Creation15(1):40–43,
1992 creation.com/kepler. Return to text.
COROT discovers smallest exoplanet yet, with a surface to
walk on, European Space Agency News, 3 February 2009, www.esa.int. But
no one is really likely to walk on it, since its temperature is between
1000 and 1500°C! Return to text.
Kalas, P. et al., Optical images of an
exosolar planet 25 light-years from Earth, Science 322(5906):1345–1348,
28 November 2008. Fomalhaut, in the constellation Piscis Australis (‘Southern
Fish’), is only 25 light years from earth, so is one of the brightest stars
in the Southern sky. Return to text.
Naeye, R., Exoplanets: The heat is on, www.skyandtelescope.com/news,
23 March 2005. ‘Hot Jupiters’ are giant planets orbiting very close
to their star. They also noted that the infrared radiation dimmed when the planet
disappeared behind the star. Return to text.
Comments are automatically closed 14 days after publication.
Feedback Guidelines
Be constructive & courteous. Don't attack individuals, denominations, or other organizations.
Stay on-topic. We're not here to debate matters like eschatology, baptism, or Bible translation.
Links to external sites and articles will be removed from your submission.
Privacy & Content Ownership
Comments become the property of Creation Ministries International upon submission and may be edited for brevity and clarity.
CMI may choose not to publish your comment depending on how well it fits the guidelines outlined above.
By submitting your comment you are agreeing to receive email updates from Creation Ministries International. You may unsubscribe at any time.
CMI records your real name, email address, and country as a sign of good faith. Privacy Policy
If your comment is published, your name will be displayed as ""
Cancel
Accept & Continue
Close
You are leaving CREATION.com
We have supplied this link to an article on an external website in good faith. But we cannot assume responsibility for, nor be taken as endorsing in any way, any other content or links on any such site. Even the article we are directing you to could, in principle, change without notice on sites we do not control.
Readers’ comments
Comments are automatically closed 14 days after publication.