Thread: We are weird!

The 'we' in this thread title refers to our solar system.

An article in New Scientist : 14 May 2011 page 47 (paper copy)

It reviews the results of extra-solar planet finding, with over 200 planets so far discovered in a little under 200 star systems. The surprise finding is that nothing like our solar system has yet been discovered.

Our solar system is atypical. We have a system with small rocky planets close to the sun, and large gas giants further out. All are in almost circular orbits, moving in a well behaved, stately way, around the sun. And of course, we have Earth in the liquid water belt, also in a beautiful, stable, almost circular orbit.

Other stellar systems have all kinds of different systems. Giant planets orbiting very close to their parent star are common. Wildly eccentic and elliptical orbits. Planets massively bigger than Jupiter. Every indication of violent interactions between bodies within those systems.

Our solar system is not normal. It is wildly different. It is stable in a way few others are. Our beautiful circular orbits are not normal. The size of our planets and the palaces they orbit are not normal. Is our solar system just weird?

And what are the implications for finding life in any other stellar system?

Wayne

I do not claim to be an expert in this field, but the authors of the New Scientist article did not think it was sampling bias. They were sure this was reality.

Originally Posted by skeptic

The 'we' in this thread title refers to our solar system.

An article in New Scientist : 14 May 2011 page 47 (paper copy)

It reviews the results of extra-solar planet finding, with over 200 planets so far discovered in a little under 200 star systems. The surprise finding is that nothing like our solar system has yet been discovered.

Our solar system is atypical. We have a system with small rocky planets close to the sun, and large gas giants further out. All are in almost circular orbits, moving in a well behaved, stately way, around the sun. And of course, we have Earth in the liquid water belt, also in a beautiful, stable, almost circular orbit....

So far we've seen about 200 fairly close planetary systems. We've still got a lot of looking to do before we can say what is typical:

It is agreed that the Milky Way is a spiral galaxy, with observations suggesting that it is a barred spiral galaxy. It contains 100-400 billion stars and is estimated to have at least 50 billion planets, 500 million of which could be located in the habitable zone of their parent star...

(ref. http://en.wikipedia.org/wiki/Milky_Way )

Chris

We're also weird in terms of timing. As the galaxy is only 15 BY young, and evolving more interesting matter (and solar systems) with every generation of stars, ours is early. Most of the galaxy is yet too "raw" for life.

If the Milky Way were a butter churn, Sol would be among the first curds formed.

I've always been interested by the idea that, planetary systems are formed from a collapsing gas cloud, and therefore, most start life with momentum towards the centre of the cloud.
At some point these systems cross the centre of the cloud passing close to each other, possibly exchanging accretion disk material and planets.

It would be interesting if the sun being bigger than average, borrowed the material for Jupiter etc. from another star's disk.

Originally Posted by PetTastic

It would be interesting if the sun being bigger than average, borrowed the material for Jupiter etc. from another star's disk.

There is no evidence from meteorite analysis to support this hypothesis and plenty of evidence to contradict it.

Originally Posted by Ophiolite

Originally Posted by PetTastic

It would be interesting if the sun being bigger than average, borrowed the material for Jupiter etc. from another star's disk.

There is no evidence from meteorite analysis to support this hypothesis and plenty of evidence to contradict it.

Sorry, I was under the impression that the main argument for water on earth coming from the outer solar system in the form of comets, was the difference between oxygen isotopes levels, that starts at Jupiter.

Just because I heard it on the Discovery channel does not make it true.

Originally Posted by PetTastic

Sorry, I was under the impression that the main argument for water on earth coming from the outer solar system in the form of comets, was the difference between oxygen isotopes levels, that starts at Jupiter.

You are absolutely correct that differences in oxygen isotope levels are a key diagnostic tool, but these reflect evolution within the accretion disk, not a pre-disk heterogenity. Chondrites, specifically carbonaceous chondrites are thought to represent the most primitive material in the solar system. If these were sourced from two disks we would have readily detected that difference.

I apply one caveat. There is recent work challenging the core formation route for giant planets. If that work is correct then the consistency of carbonaceous chondrites would not put such a dampener on your proposal - equally it would offer it zero support.

Nucleosynthesis started less than 200 million years after the Big Bang. The original Population III stars were pumping out heavier elements by the solar mass when they went supernova. So the elements of life have been around for about 13 billion years.
I doubt if it is statistically probable that 100% of the atoms in Jupiter or any of the other planets simply stayed in limbo for perhaps the age of the Sun before coalescing into the planets we know. Most likely, some of these atoms are re-cycled from other ancient star systems that have been used and reused after other SN events.

Originally Posted by Arch2008

Nucleosynthesis started less than 200 million years after the Big Bang. The original Population III stars were pumping out heavier elements by the solar mass when they went supernova. So the elements of life have been around for about 13 billion years.
I doubt if it is statistically probable that 100% of the atoms in Jupiter or any of the other planets simply stayed in limbo for perhaps the age of the Sun before coalescing into the planets we know. Most likely, some of these atoms are re-cycled from other ancient star systems that have been used and reused after other SN events.

All of that is true, but I don't see the relevance to what petastic was suggesting. The GMC from which the solar system evolved would have been reasonably homogenous. Recent 'nearby' SNs would have interjected a degree of heterogeneity, but this is different from what petastic appears to be suggesting.

Atoms for Jupiter and the other planets most likely came from other accretion disks billions of years ago. This is exactly what he is saying and I agree.

All of the atoms in the solar system came from one SN event and no where else. That does not sound reasonable to me. What do you mean by "reasonably homogenous"? If you mean that atoms from other sources may be present, then you would have to agree too.

We don't know what accretion disks were near the Sun's disk 4.5 billion years ago or how they interacted. Pop III stars explode, Pop II stars accrete the atoms and explode too. Heavier elements cool clouds of hydrogen so that smaller stars like the Sun form. Why wouldn't nearby accretion disks borrow material?

I maintain that nearby in stellar terms, even in a stellar nursery, is further apart than the dimensions of an accretion disc. Therefore no significant material from one accretion disc will find its way into another. We will certainly not have, as Petastic suggests, Terrestrial planets formed from 'our' accretion disc and Jupiter from that of another star.

Originally Posted by MeteorWayne

The editors of New Scientist specialize in fringe ideas; it ain't exactly a peer reviewed journal.

Not quite correct, Waye.

It is true that New Scientist is not peer reviewed, but that is simply because it is not a research paper journal.

It is designed as a science news journal - presenting anything new and interesting from the broad reach of science, so that interested persons can keep up with new developments. It is also partly a science education journal, with lots of general interest articles. I think it is a bit unfair to describe it as 'fringe'. It is occasionally speculative, but no more than reputable scientists are. When it reports something as 'fact', then that is because the scientists they consult in that field regard it that way.

Obviously you have to always treat what it says with some skepticism, but no more than journals like Science or Nature. Absolutely anything expressed by any human, scientist or not, has to be regarded that way.

The article on the composition of other stellar systems reports on facts. When it states that few, if any, planets have been found outside our system with near circular orbits, then you can take that as correct. Our solar system is still (so far) unique.

Actually Science and Nature regularly publish speculation. It frequently comes under the title of quantum loop gravity, or string theory, or supersymmetry, or similar.

Much of the cutting edge of science is speculation. Until an idea is tested empirically, it remains speculation.

Originally Posted by skeptic

Much of the cutting edge of science is speculation. Until an idea is tested empirically, it remains speculation.

I am inclined to put forth an educated guess that, while similar, there is (and, I'm just spit-balling here) probably some small critical difference in meaning between "speculation" and "hypothesis," or "informed proposal." This is just my conjecture, though. I could be wrong... in theory.

A hypothesis is a trial explanation. That is : it is set up to be tested, and to fail the test if it is wrong.

A speculation may not ever be tested. Of course, if a speculation is discovered to be testable by novel observation or experiment, it becomes a hypothesis. A theory is a hypothesis that has been solidly tested, and failed to be falsified.

So a speculation can become a hypothesis which can become a theory.

Einstein won the Nobel prize for his ideas on the photoelectric effect. Dr. Robert Milliken tried to destroy those ideas by experiment, and failed to do so. Einstein's original idea was a hypothesis, converted to a theory by Milliken.

However, superstring theory is speculation, because no-one knows how to test those ideas empirically.

I leave you to draw your own definitions for conjecture and informed proposal.

I don't want to risk upsetting Ophiolite again, but more general version is the idea, that the solar system was made in two stages.
Possibly the early solar system entered a new dense area of the cloud or nearby stars starting up, pushed matieral our way, after the sun had started fusion.
The solar wind from the young sun, stopped the new matieral falling in closer than Jupiter.

My thinking is you need some reason why the matierial did not enter the inner solar system.
Hense thinking it all came in one lump from another disk and then there was no tidal forces from other in falling matter to drive it into the inner system.
Or the solar wind kept it out there.

The other thing is the cosmic 'billiards contest' that went on in the early history of the solar system, which seems to have been much worse in extrasolar systems.

In our system, it is believed a Mars size object hit the Earth 4.5 billion years ago, and one result was our moon. Lots of collisions between objects in solar orbit. However, it all settled down, and life on Earth has managed to evolve for nearly 4 billion years with relatively few cosmic collision disasters to cope with.

In other stellar systems, where giant planets zip around in highly eccentric elliptical orbits, orbits of other planets will be regularly perturbed, meaning lots more disasters of that nature.

Originally Posted by PetTastic

I don't want to risk upsetting Ophiolite again, but more general version is the idea, that the solar system was made in two stages.
Possibly the early solar system entered a new dense area of the cloud or nearby stars starting up, pushed matieral our way, after the sun had started fusion.
The solar wind from the young sun, stopped the new matieral falling in closer than Jupiter.

My thinking is you need some reason why the matierial did not enter the inner solar system.
Hense thinking it all came in one lump from another disk and then there was no tidal forces from other in falling matter to drive it into the inner system.
Or the solar wind kept it out there.

This idea is very unlikely, because the solar wind extends much farther than you might think. The Pioneer probes have just reached that boundary. This pressure should be sufficient to prevent any additional material from entering the inner planetary system. In addition, your scenario contradicts the current paradigm of star and planet formation. The range from which the process gets its material is much larger than the actual planetary system. So, unless the formation of the sun was very different to the normal, well established process, I don't see how this could have happened.

Originally Posted by PetTastic

I don't want to risk upsetting Ophiolite again, .

I am afraid you have failed. I always get upset when people prefer to follow 'what they think' rather than where the evidence points.

Originally Posted by PetTastic

My thinking is you need some reason why the matierial did not enter the inner solar system.

What material is it that you think is not entering the inner solar system? There is fractionation within the accretion disc as a consequence of temperature, condensation sequences, geochemical propensities, hydrodyamic effects, charge imbalances, solar wind, orbital resonances, and a host of other phenomena. The result is a broadly homogenous body becomes very heterogenous in detail. We have a fair understanding of many of these mechanisms and are steadily integrating them into a comprehensive, realistic model. You have a vague speculation that is, at best, unnecessary.

Originally Posted by skeptic

The 'we' in this thread title refers to our solar system.
It reviews the results of extra-solar planet finding, with over 200 planets so far discovered in a little under 200 star systems. The surprise finding is that nothing like our solar system has yet been discovered.

Our solar system is atypical. We have a system with small rocky planets close to the sun, and large gas giants further out. All are in almost circular orbits, moving in a well behaved, stately way, around the sun. And of course, we have Earth in the liquid water belt, also in a beautiful, stable, almost circular orbit.
......
Our solar system is not normal. It is wildly different. It is stable in a way few others are. Our beautiful circular orbits are not normal. The size of our planets and the palaces they orbit are not normal. Is our solar system just weird?

At first glance it seems that all this is true. But consider the system Gliese 581. We write the order of the values of orbital radii: 0.030, 0.041, 0.073, 0.146, 0.220, 0.758. Multiply this numbers by 23.65. Obtain a series of numbers: 0,71, 0,97; 1.73, 3.45, 5.20, 17.9. What is it?

Comparable to the orbital radius of planets in the solar system:
0.71 ; 0.97 ; 1.73 ; 3.45 ; 5.20 ; --- ; 17.9
0.72 ; 1.00 ; 1.52 ; ---- ; 5.20 ; 9.54 ; 19.1
As you can see, there is an obvious similarity, which confirms that planetary systems are created for one scenario.

Gliese 581 is a red dwarf. The planets mentioned by Krup orbit very close in. It is a matter of pure speculation as to whether a planet around a red dwarf star can harbour life, even if it is in the "Goldilocks Zone'.
http://en.wikipedia.org/wiki/Gliese_581_c

I guess the reason Krup selected this to discuss is that the third planet out, so far discovered, is in that "Goldilocks Zone" where water would be liquid. But that planet would be 10 times the mass of Earth, and certainly would have too great a gravity for Earth life. As said, whether other life could evolved there would be a matter of speculation, since we lack any data appropriate. Personally, I am skeptical.

Originally Posted by KrupS

But consider the system Gliese 581. We write the order of the values of orbital radii: 0.030, 0.041, 0.073, 0.146, 0.220, 0.758. Multiply this numbers by 23.65. Obtain a series of numbers: 0,71, 0,97; 1.73, 3.45, 5.20, 17.9. What is it?

Comparable to the orbital radius of planets in the solar system:
0.71 ; 0.97 ; 1.73 ; 3.45 ; 5.20 ; --- ; 17.9
0.72 ; 1.00 ; 1.52 ; ---- ; 5.20 ; 9.54 ; 19.1
As you can see, there is an obvious similarity, which confirms that planetary systems are created for one scenario.

Please defend this statment, which on first glance appears to be grossly misleading, wholly inccurate and seriously foolish.

Over five hundred planets discovered so far, many of them in multiple planet systems and only one of them has orbital specifics that parallel Bode-Titius's Law. Yet you claim that single coincidence confirms planetary formation follows a single scenario only!!

Although over five hundred planets discovered so far, but there are the only 7 systems are multyplanetary enough (more 3 planet) for reliable analysis. There are : Gliese 581, Gliese 876, 55Cancri, Upsilon Andromedae A system, My Arae, HD10180, Kepler-11. And all of them have made in accordance with an universal principle (but not Bode-Titius's "Law"). More over, systems of moons of Saturn, Jupiter, Uranus have made in this way.

Then you need to clarify the character of the system you claim these planetary groupings are following. Please state it specifically in mathematical terms.

Originally Posted by Ophiolite

Then you need to clarify the character of the system you claim these planetary groupings are following. Please state it specifically in mathematical terms.

Note the following important fact. When comparing the solar system with a system Gliese 581 major satelites of the systems have coincided to each other. This is our general principle.

Let's draw up a comparative table of the six systems (left to right): Gliese 581, Solar, Saturn, Uranus, Jupiter, Gliese 876. Orbital radius of the largest satelites take equal to 1. This celestial bodies are: Gliese 581 d, Jupiter, Titan, Titania, Ganymede, Gliese 876 e. Consider the part of systems lying below the orbits of primary satelite. Obtain the table:



In celestial mechanics, there is no quantization. However, the relative positions of the planets (or moons) are very strange. Positions of the planets for some reason is not accidental. Planets tend to cluster around certain numerical values of orbital radii.

Celestial bodies, which have similar numerical values of the relative orbital radii (with respect to the orbital radius of the primary planet) , located in the same row.
-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

Of course, galaxies (like our and so others) have a planetary systems in a literal sense similar to our solar system. Scientists carefully search for these exact copies of our system, hoping to get an answer to the question how the solar system had formed. However, they wrongly neglected systems ostensibly a completely different type.

However, in reality, these supposedly radically different systems are the most interesting. Take, for example, satellite systems of giant planets. Their weight, spatial dimensions, the periods of the bodies are different in a thousand times. This systems differ in chemical composition too. But all systems have a remarkable similarity in the structure. The relative positions of the planets and satellites are very similar, despite the vast difference in absolute values.

This similarity is caused by one simple mechanism for constructing a planetary and satellite systems. Realizing the cause of the similarities, we find the clue to deciphering the formation of planets.

At first glance, the problem of "quantization" of the planetary orbits is easily solved. It is known that the Galilean satellites of Jupiter Ganymede, Europa and Io move so that the periods of treatment are as 4:2:1. The newly discovered planet e, b, c in exoplanetary system Gliese 876 move in the same way. But equality of the periods implies relations orbital radii (Kepler's third law). Thus, the equality of the relative orbital radii in systems of Jupiter and Gliese 876 is a consequence of 4:2:1 orbital resonance in these systems.

The solar system has many orbital resonances (http://quibb.blogspot.com/2010/04/or...resonance.html). This phenomenon has not yet been explained theoretically. But the presence of orbital resonances for planets and moons in our planet system to suggest that orbital resonances exist in other planetary systems.

Here is a table of the relative resonant orbits:

The numbers in its cells are calculated by Kepler's third law:

where n-number of the column, m - row number.

Using the table, we can know whether the two planets are in a state of orbital resonance. Take, for example, Jupiter and Saturn, the orbital radii are equal, respectively, 5.20 and 9.54 astronomical unit. 5.20 / 9.5 = 0.545. This number is very close to the tabulated number of 0.543 at the intersection of the fifth row and second column. Hence the periods of Jupiter and Saturn are approximately 2:5 (approximate 2:5 orbital resonance).

Note that the number of rows 3,4,5,7 in a comparative table of six systems are very similar to the bold numbers in Table resonances. The numbers in row 9 of comparative tables are also close to the value:

for the resonance of 1 / 12.

For easy comparison, I repeat below a table comparing the six systems.