Extrasolar Planets – What Are They Telling Us?

 

The Bible in Gensis 1:14-19 gives the account of the creation of the Universe.

These versues confirm that God created the Sun,the planets, asteroids, and comets of not only our solar system but other planetary systems as well. 

Before 1992, the only planets that were known were those in our solar system.  Many astronomers thought that there should be planets orbiting around other stars. However, since it would be all but impossible to see something that faint so near the blazing light of their parent star, they just had to keep speculating. 

That all changed on January 9th, 1992 when Nature reported the shocking discovery that there were other planets outside our solar system.  Using the Arecibo Radio Observatory in Puerto Rico, astronomers detected that two planets were orbiting the pulsar PSR B1257+12. Here is an artist’s representation of how the system might look.

Description: File:Ssc2006-10c.jpg

Credit: WikiMedia

Their orbits are 0.36 and 0.47 AU respectively. Eventually, a third planet was discovered in the system. Two of the planets orbit closer than Mercury while the the thrid planet is just outside Mercury’s orbit. 

Before we move on, it would be good to understand the naturalists thinking of how stellar systems and even our own solar system developed.  That way we can compare their model to the actual observations and see how well the model holds up. 

Description: Evolution of our Solar System.

Credit: J.Wiley & Sons, Inc.

First of all, we need dust clouds. These clouds contain mostly hydrogen and some heavier metals. Any element that is heavier than helium is considered a metal by Astronomers. These metals are created in stars by a process called fusion and the very heavy elements are created when they explode.  

 

When a star ends its life, it explodes in an event called a supernova. These elements "seed" surrounding hydrogen clouds so that newer stars will contain these heavier elements in their atmospheres as well as the heavier elements needed for planet formation.  

 

Description: http://chandra.harvard.edu/photo/2007/sn2006gy/sn2006gy_newline.jpg

Image credit: NASACXC/M.Weiss

It is believed that for a system of planets to form around a star, a cloud full of heavy elements contracts if it contains a certain amount of material and is a certain size. However, if a cloud exists outside of these parameters it must get some help.

Description: http://astronomyonline.org/SolarSystem/Images/ProtoplanetaryDisks.jpg

Credit: NASA/STSci

This image from the Hubble Space Telescope is thought to show a solar nebula, located in Orion Nebula. The darker area is the dense molecular cloud while the proto-star is the glow in the center. This picture is touted as proof that the Nebular Hypothesis Theory is true.

Also, there are stars that already seem to have started the planet formation process. This is an image of the star Beta Pictoris.

Description: The rings of Beta-Pictoris.

The image shows that this star has 4 distinct rings. It is believed that these rings will eventually coalesce into planets.

Our Solar System has three distinct features as a direct result of its formation:

Description: C:\Users\Dad\Documents\Exoplanet\extrasolar protoplanetary disk drawing.jpg

Credit: Science Daily

As the Solar Nebula contracts a natural disk shape forms as a result of the conservation of energy. The planets begin their lives as very small clumps of debris with in this disk. They continue to grow into what are called planetesimals as they assume their orbits and gather surrounding debris in a process called sweeping. Because the terrestrial planets form close to the proto-sun, which at this point has not initiated fusion, any ice will melt away so all that is left are the rocky planets.  The Gas Giants are at a greater distance and much of the ice and gas remains.

During the sweeping process, the protoplanets undergo another natural phenomenon called chemical differentiation, a process by which heavy elements sink towards the center of the object while the light elements remain closer to the surface.

During all of this planet evolution, the proto-sun in continuing to contract until it finally ignites into nuclear fusion.

Description: C:\Users\Dad\Documents\Exoplanet\Graphic - Clearing Protoplanetary Disk - Universe Today.jpg

Credit: Science Daily

When the Sun ignites, the result is a shock wave called T Tauri Wind. This wind is strong enough to blow away any gas in the inner Solar System, but not strong enough to strip away the thick atmospheres from the Gas Giants.

The asteroid belt creates a natural boundary between the terrestrial and gaseous planets, but it could have been a planet. The gravity influence of Jupiter is believed to be enough to prevent the asteroids from coalescing into a planet.

This is an artist’s impression of the almost competed solar system.

Description: C:\Users\Dad\Documents\Exoplanet\Image - epsilon eridani planetary system - NASA JPL.jpg

Credit: WikiMedia

The important point is that the planets move in the same direction in their orbits as the disk spins because the planets get their orbital energy from the disk. Planets by this idea would form in circular orbits moving in their orbit in the same direction that the star spins.

Here is our solar system today.

Description: Solar System drawn to scale

Credit: Ipatrix.com

So, what is their proof for the nebular hypothesis?

 

·        The orbits of the planets lie nearly in a plane with the sun at the center.

·        The planets all orbit the Sun in the same direction.

·        The planets mostly rotate in the same direction with their axis of rotation nearly perpendicular to the orbital plane.  Not true!

Ø Venus – rotates backwards and barely rotates at!

Ø Uranus – rotates on its side!

Ø Pluto – rotates backwards!

So, we have the rocky terrestrial planets near our Star and the gas giants out pass five AU.

So, this is what we should be finding in other stellar systems.

On October 6th, 1995, the first extra solar planet orbiting around a “normal” star was discovered by Michel Mayor and Didier Queloz using the radial velocity method and was published in Nature.  The planet was discovered orbiting around the star 55 Pegasi which is about 50 light years from Earth. This is an artist’s representation of 55 Pegasi b. 

Description: File:51pegasi-b.jpg

Credit: WikiMedia

The planet is half the mass of Jupiter yet it orbits 19 times closer to its star than the Earth’s distance from the Sun or about 0.05 AU, well inside the orbit of Mercury.  It orbits around the star in about four days and its surface temperature is thought to be somewhere around 1500 degrees Fahrenheit.  Not surprisingly, these types of planets are often referred to as “Hot Jupiters”.

The existence of a large gas planet so close to its star was quite a shock to secular astronomers. Secular models of planet formation predicted that other solar systems would be in essence like ours: with the small rocky planets (like Venus and Earth) orbiting relatively close to their stars, and the big gas giant planets (such as Jupiter) orbiting much further away.

Indeed, it was thought to be virtually impossible to have a gas giant so close to the star since the models require that gas giants begin with icy cores, which cannot exist so close to a star.  So it is interesting that the very first planet discovered orbiting a solar-type star defied their predictions.

Since 51 Pegasi b went against these predictions, it was considered an anomaly at first. However, far more hot Jupiters have been discovered than any other type of planet.

To be quite honest, this finding is at least partly explained by the limitations in the method for detecting extrasolar planets. It is far easier to find hot Jupiters than smaller or more distant planets. So many smaller extrasolar planets in larger orbits have probably not yet been discovered. Nonetheless, the fact that hot Jupiters exist at all is a challenge to the secular models. However, it is perfectly consistent with the creative diversity we expect from the Lord.

Another aspect of extrasolar planets that challenges the secular models is the eccentricity of their orbits. “Eccentricity” describes how elliptical their orbits are. The planets in our solar system have very low eccentricity, which means their orbits are nearly circular. By the way, life on earth would not be possible if our distance from the sun changed dramatically.

Since secular astronomers believe stellar systems would have formed just like ours, they were expecting other stellar systems to have nearly circular orbits like ours. Yet many extrasolar planets have orbits that are quite elliptical.

Let us take for example, the extra solar planet that orbits around the star Epsilon Eridani which is a little over 10 light years away. Here is a very imaginative artist’s representation of what the planet might look like complete with a couple of moons!

 Description: File:Epsilon Eridani b.jpg

Credit: WikiMedia

The planet is believed to be over one and a half times the mass of Jupiter.  However, to give you an idea how weird this planet is the Earth’s eccentricity is only 1.67%, measured by how far its orbit deviates from a perfect circle. But Epsilon Eridani b’s eccentricity is thought to range from 25% to as much as 70%!  However, there are others who argue against this.  This is what makes the study of extrasolar planets so much fun!

To date, the closest extrasolar planet to being Earth-sized is one called Gliese 581e, which is about twice Earth’s mass. The star Gliese 581 is about 20 light years from Earth but only about a third of the mass of the Sun.  Here is a comparison of its system as compared to our solar system.  

Description: Graphic - Gliese 581 System.jpg

Credit: NASA

Gliese-581 is a system with four objects generally accepted as being planets. Even though Gliese-581e is thought as being close to the Earth in mass, it is too hot to be habitable and is tidally locked with one side always facing its parent star like our Moon has only side that faces the Earth .

In 2010, one group of researchers announced discovery of two additional planets in the Gliese 581 system, labeled as objects f and g. One of them, 581g, was initially called the first “Goldilocks planet,” the first extrasolar planet believed to be in the habitable zone for that star. This is an area from the star where with the right conditions, like a suitable atmosphere, water can stay liquid. By the way, later efforts, however, by another team of researchers were not able to confirm the detection of objects f or g.

As we mentioned, models do not predict the large Jupiter mass planets so close to their parent star. So, astronomers began exploring other shall we say very creative theories that would allow a Jupiter-like planet to form several astronomical units distance from the star out past a place called the “snow line” where ices can form its core and then move inward. This idea, now generally accepted, is known as orbit migration.  The Upsilon Andromeda star system is a classic example!

Description: Illustration - Exoplanets  of Upsilon Andromendae.gif

In the orbit migration model, while planets are pulling together from a disk of dust and gas, part of the disk is massive enough to cause the newly forming planet's orbit to change. Thus the disk can theoretically cause the planet to migrate, either inward or outward from the star. When the disk dissipates and becomes too thin, it would stop modifying the planet’s orbit. However, the thorny problem of having the planet stop from crashing into its star has not been worked out. They need to literally put brakes on the planet.

Some of the extrasolar planets are in extremely close orbits around their parent star. One example was discovered in 2008 and further studied by the Hubble Space Telescope in May 2010. This planet is called WASP-12b.  WASP is an acronym for Wide Area Search for Planets, which uses two special telescopes to do an automated search for transiting planets. WASP-12 is a yellow star approximately 327 light-years from Earth and has one and a third the mass of our Sun. The planet, WASP-12b, is so near the star that matter is being pulled off the planet, creating a significant cloud of material around the planet that falls onto the star.  This is an artist’s impression of how this might look.

Description: File:WASP-12b (NASA).jpg

Credit: WikiMedia

The planet is thought to be almost one and a half times the mass of Jupiter and is in an extremely close orbit. In fact it is so close, that it only takes a little over a day to make an orbit around its parent star.  Since it is so close, the planet is probably stretched out in shape similar to a football.

What is interesting is that astrophysicists believe the star is 1.7 billion years old. However, we have a problem. It has been estimated WASP-12b could be essentially eaten up by its star in only 10 million years or less. The planet and the star could thus be only thousands of years old. There are other similar examples of extrasolar planets that cannot last long since they are so near their stars.

On April 12, 2010 the Royal Astronomical Society published a press release called “Turning Planetary Theory Upside Down.”  In the press release, it reports six cases of extrasolar planets that were found to be orbiting their stars in a direction opposite the direction of spin of their stars!  This is huge!!

The six retrograde extrasolar planets are all from the WASP research program. Here is an artist’s impression of one of them called WASP 8b.

Description: Image: Exoplanet WASP-8b

Credit:  L. Calgada/ESO

Also, their retrograde orbits are not the only thing that has turned planetary theory upside down.  These six extrasolar planets have their orbits inclined more than 90 degrees as compared to the equators of their stars!

 As was said earlier, much research has gone into developing the theory for how a dust disk around a star might cause forming planets to migrate. But there is no way a dust disk, which must be aligned with the star's equator, can cause planetary orbits to tilt by over 90 degrees and also be in a retrograde orbit.

Of course, from a creation perspective, God can create planets orbiting their star at any inclination He pleases!  But how will scientists who are insisting on a naturalistic explanation explain this?  They are hard at work, I am sure!

And to make things very interesting, let us take a look at the KOI-730 planetary system. There are four planets that make up this system but two planets circle their sun-like parent star every 9.8 days at exactly the same orbital distance. Here is an artist’s representation of what this might look like.

Description: Room for two (Image: NASA/Ames/JPL-Caltech)

Credit: NASA/Ames/JPL-Caltech

Actually, this has been good news for the giant impact origin of our moon folks.  Such co-orbital planets are thought to be the origin of the impact that produced the Earth-Moon system.  As the Earth was peacefully orbiting the young Sun, its co-orbit buddy named Theia, snuck up and collided with us and thus produced the Moon.  

However, others argue that the data does not support that KOI-730 has two co-orbital planets.  So far, the co-orbital planet data seems to be holding up.   

Wrapping this up, here is a plot showing the extra solar planet census through the end of last year.  As a reference, Earth is 0.00317 Jupiter mass according to our friends at NASA.

Description: http://oklo.org/wp-content/uploads/2011/02/Screen-shot-2011-02-07-at-10.02.10-PM.gif

Credit: Systemic

As of last Friday, a total of 539 extra solar planets have been discovered and catalogued. Of these, over 90% were discovered using the radial velocity method. Also, so far to date only about 11% are multi planet systems.

What we have found in these extrasolar planetary systems:

·        Giant Jupiter sized and even larger extrasolar planets orbiting very, very close to their parent stars. 

·        Several extrasolar planets with their orbits around their parent stars incline by more than 90%  

·        Extrasolar planets with huge eccentricities of up to 70%

·        Several extrasolar planets orbiting their parent stars backwards

·       Data revealing at least two extrasolar planets sharing the same orbit

So after visiting these extrasolar planetary systems we can truthfully say….

Description: File:Judy Garland in The Wizard of Oz trailer 2.jpg

Credit: MGM

Yes, Dorothy, we are not in Kansas anymore!

Although extrasolar planets challenge the secular understanding of the universe, they are consistent with the creative diversity of the Lord.  God has created some very intriguing and unexpected types of star systems, which do not fit into astronomers’ preconceived boxes of what’s possible or even “likely.”

It is important for us to remember that God created all these stars and planets on Day 4 of creation week. So far, they demonstrate just how special our own home planet and even our solar system really are.  

The bottom line is that our planet and our solar system have been created with the purpose of giving us a safe stable environment. This should motivate us to want to really know and worship our Creator.

Going back to our original question of what are the extrasolar planets telling us?

Psalm 19:1

Acknowledgements