(June 2, 2014 at 6:19 pm)Heywood Wrote:

(June 2, 2014 at 2:02 pm)Cthulhu Dreaming Wrote: Is that a case of selection bias (whereby higher-mass planets are easier to spot using current detection methods)?

The Kepler space telescope was designed to be able to spot earth sized exo-planets.

Yes, I'm aware of that. I'm also aware that there are a number of other detection methods which aren't - which is why I asked the question.

ETA: It's an entirely separate matter as to whether or not earth-size/mass planets are *as easy* to identify as larger/more massive ones. In other words, are we finding fewer of them because they are fundamentally harder to detect - which they are.

(June 2, 2014 at 6:21 pm)Cthulhu Dreaming Wrote:

(June 2, 2014 at 6:19 pm)Heywood Wrote: The Kepler space telescope was designed to be able to spot earth sized exo-planets.

Yes, I'm aware of that. I'm also aware that there are a number of other detection methods which aren't - which is why I asked the question.

ETA: It's an entirely separate matter as to whether or not earth-size/mass planets are *as easy* to identify as larger/more massive ones. In other words, are we finding fewer of them because they are fundamentally harder to detect - which they are.

If Kepler found fewer than expected there are two possible reasons:
A) Kepler's design was flawed.
B) Our models of the dynamics of solar system formation are wrong.

(June 2, 2014 at 10:03 pm)Heywood Wrote:

(June 2, 2014 at 6:21 pm)Cthulhu Dreaming Wrote: Yes, I'm aware of that. I'm also aware that there are a number of other detection methods which aren't - which is why I asked the question.

ETA: It's an entirely separate matter as to whether or not earth-size/mass planets are *as easy* to identify as larger/more massive ones. In other words, are we finding fewer of them because they are fundamentally harder to detect - which they are.

If Kepler found fewer than expected there are two possible reasons:
A) Kepler's design was flawed.
B) Our models of the dynamics of solar system formation are wrong.

I have no doubt b) is true to a certain extent. Our sample size and corpus of data is too small. They are at least incomplete, and I doubt there many planetary scientists who think otherwise.

I'm not privy to what was expected - so won't comment on a) or whether additional possibilities exist.

(June 2, 2014 at 10:03 pm)Heywood Wrote:

(June 2, 2014 at 6:21 pm)Cthulhu Dreaming Wrote: Yes, I'm aware of that. I'm also aware that there are a number of other detection methods which aren't - which is why I asked the question.

ETA: It's an entirely separate matter as to whether or not earth-size/mass planets are *as easy* to identify as larger/more massive ones. In other words, are we finding fewer of them because they are fundamentally harder to detect - which they are.

If Kepler found fewer than expected there are two possible reasons:
A) Kepler's design was flawed.
B) Our models of the dynamics of solar system formation are wrong.

Where's C) gawd dun did it ?

(June 2, 2014 at 10:03 pm)Heywood Wrote:

(June 2, 2014 at 6:21 pm)Cthulhu Dreaming Wrote: Yes, I'm aware of that. I'm also aware that there are a number of other detection methods which aren't - which is why I asked the question.

ETA: It's an entirely separate matter as to whether or not earth-size/mass planets are *as easy* to identify as larger/more massive ones. In other words, are we finding fewer of them because they are fundamentally harder to detect - which they are.

If Kepler found fewer than expected there are two possible reasons:
A) Kepler's design was flawed.
B) Our models of the dynamics of solar system formation are wrong.

Kepler's design is near the limits of our current technologies. So, not A.

Detection has nothing to do with the dynamics of solar system formation. So, not B.

Smaller planets are harder to detect.

(June 2, 2014 at 10:08 pm)Cthulhu Dreaming Wrote:

(June 2, 2014 at 10:03 pm)Heywood Wrote: If Kepler found fewer than expected there are two possible reasons:
A) Kepler's design was flawed.
B) Our models of the dynamics of solar system formation are wrong.

I have no doubt b) is true to a certain extent. Our sample size and corpus of data is too small. They are at least incomplete, and I doubt there many planetary scientists who think otherwise.

I'm not privy to what was expected - so won't comment on a) or whether additional possibilities exist.

It's not that our model of the dynamics of solar system formation are wrong. It's our model is supersensitive to initial as well as boundary conditions, and it is extremely difficult to solve. So to get anywhere near a solution that resemble our own solar system - the only one we knew until early 1990s - we used many simplifying assumptions.

But once we got rid of those assumptions of convenience, we found our model of solar system formation could lead to much wider range of outcomes than we imagined, and our solar system with orderly arrangement of small rocky planets inside, large gaseous plants in the middle, and moderate sized ice giants on the outside in fact seem to represent a very unlikely outcome. In most cases, the orbits of gas giants swing all over the place, often ending up near to or colliding with the parent star, but in the process clear the planetary system of any incipient small mass rocky planets.

And then there is the Fermi paradox . . .


We are seeing far 'weirder' (FLOABT) solar systems than almost anyone would have imagined. I recall some earlier planetary system formation studies/simulations Carl Sagan wrote about in (IIRC) Communication With Extraterrestrial Intelligence, and at the time it was believed scientists/astronomers understood the formation process as the software generated recognizable variations on the only solar system known at the time. It seems that was a tad optimistic. Sigh.

I think the consequences for the Drake Equation is an (unfortunate) severe decrease in the % of what me might consider to be 'nice' planets, but a compensating increase in the overall total number of planets. It was noted even back in the 60s that due to observed stellar rotational results, planets would be increasingly rare around F and A stars, and this might be correct.

LOL, he also wrote about a (very) hypothetical gamma ray laser device of extraordinary power and an interesting use to which it might be put. I note, if there was such a device anywhere in our galaxy being used that way in the last 100,000 years (m/l), we would be aware of it.

Interestingly it is 11 billion years old apparently. That's much older than we thought rocky planets could be.

Also raises the question - why did God wait another 6.5 billion years before creating the earth?

Sometimes its almost as if there is no God.

(June 2, 2014 at 11:39 pm)vorlon13 Wrote: And then there is the Fermi paradox . . .

Fermi paradox could possibly be resolve if we assume much of those who possess technology even more advanced than that which seem like magic to us would for various reasons make themselves invisible to us, ie the window of opportunity in which a technological civilization could reveal itself to us and would chose to reveal itself to us is very slim next to the time span such a civilzation might exist. So only a tiny fraction of civilzations that has the capacity to make itself known to us would actually allow itself to be known to us.

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(June 3, 2014 at 12:34 am)max-greece Wrote: Interestingly it is 11 billion years old apparently. That's much older than we thought rocky planets could be.

Wouldn't really think so. Most of the materials from which terresterial planets are made were created inside very large, short lived stars that go supernova at the end of their lives. These stars have life expectancies measured in millions, not billions of years.

Current view is Universe is 13.7 billion years old, and the first generation of stars were around by 13 billion years ago.

By the time this planet formed 11 billions ago, the universe already had 2 billion years, enough to go through several dozen of generations of stars that manufactured and distributed terresterial planet material, to prepare the scene for terresterial planet formation.

(June 3, 2014 at 12:08 pm)Chuck Wrote:

(June 3, 2014 at 12:34 am)max-greece Wrote: Interestingly it is 11 billion years old apparently. That's much older than we thought rocky planets could be.

Wouldn't really think so. Most of the materials from which terresterial planets are made were created inside very large, short lived stars that go supernova at the end of their lives. These stars have life expectancies measured in millions, not billions of years.

Current view is Universe is 13.7 billion years old, and the first generation of stars were around by 13 billion years ago.

By the time this planet formed 11 billions ago, the universe already had 2 billion years, enough to go through several dozen of generations of stars that manufactured and distributed terresterial planet material, to prepare the scene for terresterial planet formation.

I wouldn't think so, either. The population III stars (i.e. the oldest metal-free[*] stars) are currently thought to have been (at least in part) supermassive giant stars that went supernova after only a few million years, seeding the area with the first 26 elements (as heavy as iron). None of these stars have ever been observed, their existence is inferred both from cosmological models and observation of quasar spectra. If any long-lived population III stars still exist, they would have to be too small to be observable or go supernova.

The population II stars (relatively metal-poor, compared to later similar population I stars) are believed to have first produced the other elements - pop II stars that we can observe today are *ancient*, up to almost the very beginning of star formation. After several generations of forming short-lived supermassive pop III stars, it's quite conceivable within existing models that there would be early pop II stars that lived fast, died young, producing the elements heavier than iron - and, really, elements heavier than iron are not required to form terrestrial planets.

Kepler 10 is a type G star like our sun, with 70% of the sun's metallicity. Given it's mass, age, and metallicity, it would be within the population II group (our sun is population I). Iron, et al, were obviously present in quantity when Kepler 10 formed (a star with Kepler 10's mass would not produce iron, it would have to be present at time of formation).

I don't see a problem with 11-billion year old rocky planets either.

[*] In this context, "metal" means elements heavier than helium.