Implications of Exoplanet Research?

[Geschosskopf]

So Kepler and various other things have now found thousands and thousands of exoplanets, enough to be statistically significant in terms of what the average solar system looks like in this part of our galaxy.  AFAIK, this vast amount of data doesn't yet contain a solar system that looks anything like ours.  Instead, the planets of other stars seem to cluster in 2 main classes:

• "Hot Jupiters" where gas giants have apparently migrated all the way in to sub-Mercurian orbits, obliterating everything in their path, and;
• "Super Earths", with 1 or more really massive rocky planets in the inner solar system, usually with at least 1 such thing in a sub-Mercurian orbit.

The sizes and positions of the planets we can see seems to make it quite unlikely that smaller, Earth-like planets can exist in such systems, at least in places where conditions like our prevail.  IOW< it's not a question of needing better telescopes to see smaller planets, it's that smaller (Earth-scale) planets just aren't there.  

This information has tossed all previous ideas of how our solar formed out the window.  We originally thought we were normal and had theories that would usually produce something like our solar system, but those all failed to make what we see at other stars.  So then the scientists developed models that would usually make what we see at other stars, but these don't make what we have here.  So now they're working on the special pleading necessary to create our solar system given what they now know about other solar systems.

All this I think has some rather profound implications.  Such as, we live in what is apparently a very rare statistical outlier of a solar system, which given what we see around us shouldn't be expected to exist.  Then you combine this with all the other variable that we depend on within our solar system, such as a star that's stable and warm enough to count, being the right distance from it, and having a massive moon to keep our planet's axis from tumbling.

So, here we are.  There doesn't seem to be much if anything like us out as far as we can see.  Thus, assuming that some of these "Super Earths" we see have the other necessities for life, it seems that we'd be the runts of the litter on the cosmic scale of life.  Aliens would likely be rather squat, massive things with many legs, the better to cope with their high native gravity.  So much for waif-like "greys" .  They would no doubt look on us as as toy-sized things, the same as we view Kerbals.

But OTOH, as with Kerbals, it would be comparatively easy for us to get to space compared to what seems to be the galactic norm.  We find getting stuff to orbit a very hard (or at least expensive) task but pity the poor folks on "Super Earths", with much more gravity and presumably denser atmospheres to deal with.  Thus, having things comparatively easy, we might end up visiting the aliens before they can visit us, and we'd be the waif-like "greys" to them.

Thoughts?

[UmbralRaptor]

As best I'm aware, hot jupiters are actually fairly rare (~1-10% of sunlike stars). The super earths are still weird, especially given how they seem to be more common than terrestrial planets. Uh, note that the habitability of them is still ¯\_(ツ)_/¯ and anything above ~1.6 earth-radii is more of a sub neptune.

 

Unrelated, why is U+1F728 (or for that matter, unicode plane 14) banned by the forum software? o_O

Edited May 14, 2016 by UmbralRaptor

[Shpaget]

 

1 hour ago, Geschosskopf said:

statistically significant in terms of what the average solar system looks like in this part of our galaxy

Actually, I would think that this data is significantly skewed towards large and low orbit planets. They are much easier to detect than smaller ones further out, so I would assume that the ratio of detected / existing large low orbit planets is much closer to 1 compared to detected / existing small high orbit ones.

In any case, from http://kepler.nasa.gov/news/nasakeplernews/index.cfm?FuseAction=ShowNews&NewsID=415

Quote

550 of the 1,284 new Kepler planets are small possibly rocky; 9 of those reside in habitable zone.

9 out of 1284, that's almost 1%, that's a huge number of planets.

[PB666]

2 hours ago, Geschosskopf said:

So Kepler and various other things have now found thousands and thousands of exoplanets, enough to be statistically significant in terms of what the average solar system looks like in this part of our galaxy.  AFAIK, this vast amount of data doesn't yet contain a solar system that looks anything like ours.  Instead, the planets of other stars seem to cluster in 2 main classes:

• "Hot Jupiters" where gas giants have apparently migrated all the way in to sub-Mercurian orbits, obliterating everything in their path, and;
• "Super Earths", with 1 or more really massive rocky planets in the inner solar system, usually with at least 1 such thing in a sub-Mercurian orbit.

The sizes and positions of the planets we can see seems to make it quite unlikely that smaller, Earth-like planets can exist in such systems, at least in places where conditions like our prevail.  IOW< it's not a question of needing better telescopes to see smaller planets, it's that smaller (Earth-scale) planets just aren't there.  

This information has tossed all previous ideas of how our solar formed out the window.  We originally thought we were normal and had theories that would usually produce something like our solar system, but those all failed to make what we see at other stars.  So then the scientists developed models that would usually make what we see at other stars, but these don't make what we have here.  So now they're working on the special pleading necessary to create our solar system given what they now know about other solar systems.

All this I think has some rather profound implications.  Such as, we live in what is apparently a very rare statistical outlier of a solar system, which given what we see around us shouldn't be expected to exist.  Then you combine this with all the other variable that we depend on within our solar system, such as a star that's stable and warm enough to count, being the right distance from it, and having a massive moon to keep our planet's axis from tumbling.

So, here we are.  There doesn't seem to be much if anything like us out as far as we can see.  Thus, assuming that some of these "Super Earths" we see have the other necessities for life, it seems that we'd be the runts of the litter on the cosmic scale of life.  Aliens would likely be rather squat, massive things with many legs, the better to cope with their high native gravity.  So much for waif-like "greys" .  They would no doubt look on us as as toy-sized things, the same as we view Kerbals.

But OTOH, as with Kerbals, it would be comparatively easy for us to get to space compared to what seems to be the galactic norm.  We find getting stuff to orbit a very hard (or at least expensive) task but pity the poor folks on "Super Earths", with much more gravity and presumably denser atmospheres to deal with.  Thus, having things comparatively easy, we might end up visiting the aliens before they can visit us, and we'd be the waif-like "greys" to them.

Thoughts?

Rather unpopular notion here, however much i agree with you we tend to have alot who don't seem to accept that version as real, they see aliens under every red dwarf. BTW dont assume denser atmospheres, the magnetic field of the earth is another rarity. 

There is of course the problem of detection we can't see all planets around all stars, 

40 minutes ago, Shpaget said:

 

Actually, I would think that this data is significantly skewed towards large and low orbit planets. They are much easier to detect than smaller ones further out, so I would assume that the ratio of detected / existing large low orbit planets is much closer to 1 compared to detected / existing small high orbit ones.

In any case, from http://kepler.nasa.gov/news/nasakeplernews/index.cfm?FuseAction=ShowNews&NewsID=415

9 out of 1284, that's almost 1%, that's a huge number of planets.

Habitable zone does not equal habitable, for any given planets real time characteristics that zone is quite thin. Its a zone in which given all characteristics a few might suuprt life. As of yet we have not discovered a planet we might think is inhabited. 

[magnemoe]

5 hours ago, Shpaget said:

 

Actually, I would think that this data is significantly skewed towards large and low orbit planets. They are much easier to detect than smaller ones further out, so I would assume that the ratio of detected / existing large low orbit planets is much closer to 1 compared to detected / existing small high orbit ones.

In any case, from http://kepler.nasa.gov/news/nasakeplernews/index.cfm?FuseAction=ShowNews&NewsID=415

9 out of 1284, that's almost 1%, that's a huge number of planets.

Yes, this is seen even more in the low number of mars sized or smaller planets who should be common. 
 

4 hours ago, PB666 said:

Rather unpopular notion here, however much i agree with you we tend to have alot who don't seem to accept that version as real, they see aliens under every red dwarf. BTW dont assume denser atmospheres, the magnetic field of the earth is another rarity. 

There is of course the problem of detection we can't see all planets around all stars, 

Habitable zone does not equal habitable, for any given planets real time characteristics that zone is quite thin. Its a zone in which given all characteristics a few might suuprt life. As of yet we have not discovered a planet we might think is inhabited. 

Habitatable zone depend a lot on atmosphere too, an large planet with an thick atmosphere would do well in mars orbit or outside. 

[SargeRho]

I wonder, would Kepler actually be able to tell a super-earth from an earth-like planet with a very large moon?

[Kryten]

1 hour ago, SargeRho said:

I wonder, would Kepler actually be able to tell a super-earth from an earth-like planet with a very large moon?

It uses transit detection, so yes.

[insert_name]

The transit method usually fails to detect planets with long orbital periods or small ones, it seems like an alien civilization with a Kepler like probe couldn't detect mercury or any of the outer planets

[Geschosskopf]

10 hours ago, UmbralRaptor said:

As best I'm aware, hot jupiters are actually fairly rare (~1-10% of sunlike stars). The super earths are still weird, especially given how they seem to be more common than terrestrial planets. Uh, note that the habitability of them is still ¯\_(ツ)_/¯ and anything above ~1.6 earth-radii is more of a sub neptune.

OK, I wasn't clear.  Large gas giants seem, somewhat surprisingly, to be rather rare out there overall.  But when we do see them, most of them are of the hot variety instead of the cold type we have.

I wasn't saying the Super Earths were all habitable or even in habitable zones.  I was just saying that, at those stars where terrestrial planets exist at all, they are very likely to be Super Earths.  Thus, if an alien terrestrial planet happens to have life on it, the odds strongly favor it being a Super Earth, because Super Earths are where solid ground appears to be in the average star system.

 

9 hours ago, Shpaget said:

Actually, I would think that this data is significantly skewed towards large and low orbit planets. They are much easier to detect than smaller ones further out, so I would assume that the ratio of detected / existing large low orbit planets is much closer to 1 compared to detected / existing small high orbit ones.

Sure, it's easier to see bigger things.  But that's not the point.  The point is, big things eat or eject small things.  Thus, where you see big planets, and can determine how far out they are from the star, you can exclude the possibility of smaller things existing at other distances.

As it happens, we see big planets pretty much everywhere we look.  The nearly ubiquitous presence of these big planets means that even if we had better equipment, we still probably wouldn't find many planes of Earth's size or smaller because the big planets destroyed them.

9 hours ago, Shpaget said:

In any case, from http://kepler.nasa.gov/news/nasakeplernews/index.cfm?FuseAction=ShowNews&NewsID=415

Yes, exactly.  Consider this graphic from that page:

 

As you can read across the top of the chart, our solar system doesn't correspond at all to what we see out in the galaxy.  We have stuff at both flow-frequency ends of the graph and none of the common stuff in the middle.  We are, therefore, living in a very unusual place compared to the galactic norm.

Things the size of our gas giants are much bigger than Super Earths and so should be easier to spot.  But we don't see that many of them; instead we see lots of Super Earths.  Yet we have not just 1 but 4 gas giants, plus 4 tiddlers of terrestrial planets, and no Super Earths at all.  And we have nothing closer to the Sun than Mercury, yet other stars often have 1 or more planets (Super Earths or a Hot Jupiter) closer in than that.

Therefore, any models of how star systems form must be based not on our own solar system, but on what seems to be the typical system we see around us.  Then we have to explain how our system ended up like it is despite what apparently is the very strong tendency for things to work out otherwise.

A recent Scientific American had an article on trying to answer this question.  According to it, we did indeed have some nascent Super Earths, even some inside of Mercury, but Jupiter wandered inwards, as gas giants do, as far as Mars' orbit and made the Super Earths fall into the Sun.  Then for some reason Jupiter wandered back out to where it is now, leaving behind only dregs in the inner solar system that ultimately became our stunted collection of terrestrial planets and the asteroid belt.  I forget how it explained the formation of 3 more gas giants but it also had something to do with Jupiter's travels.

Nobody in the scientific community, not even the author of this article, thinks they really know how our solar system ended up like it did.  But they all seem to agree that we're quite abnormal.  And because of that, our theories of planetary formation have heretofore been totally wrong because they were based on what is turning out to be an anomalous data point.

 

8 hours ago, PB666 said:

Rather unpopular notion here, however much i agree with you we tend to have alot who don't seem to accept that version as real, they see aliens under every red dwarf. BTW dont assume denser atmospheres, the magnetic field of the earth is another rarity. 

Yeah, the magnetic field, too.  Personally, I think the universe is full of at least microbial life simply because it appears that the way our Periodic Table works, organic molecules of increasing complexity just seem to happen by themselves.  Pile enough of that sludge up, apply some energy, and life of some sort will probably appear eventually.

But where, if anywhere, it goes from there, is a different story.  Most stars are small, dim, and prone to violent flares, so aren't nice to live next to. Most stars also come in groups, the gravitational interplay of which isn't conducive to long-term planetary stability.  And then there are the special circumstances that created both our unusual solar system and the Earth-Moon system itself (a planet with a "training wheel" and an effective magnetic field).  So if we think of intelligent aliens as requiring a place like Earth, there probably aren't many of them out there.  With "billions and billions" of chances for another Earth to form, it's certainly happened more than once, but it can't be a statistically common thing.

Anyway, assuming you have a planet in the habitable zone, and it's got an effective magnetic field, and is in a system that allows long-term stability, odds are that planet will be a Sub-Neptune or a Super Earth.  So high gravity and dense atmosphere.  Getting to orbit from such a place would be way harder than it is for us.

[ProtoJeb21]

12 hours ago, Geschosskopf said:

This information has tossed all previous ideas of how our solar formed out the window.  We originally thought we were normal and had theories that would usually produce something like our solar system, but those all failed to make what we see at other stars.

I don't think our solar system is the normal we thought it was. And I don't mean that it is unusual; we've just mistaken it.

Take a look at Mercury. It may seem boring and ordinary, but there are some unusual things about it. For example, its abundance of iron, water ice on the surface for no reason, its eccentric orbit, and depleting hydrogen/helium atmosphere. Not to mention that, for some reason, there's lithium on the Sun's photosphere. Do you get where I'm going? I believe that Mercury is the remains of a gas dwarf that was shoved too close to the Sun. Most of its atmosphere was blown off and consumed, and some of the icy mantle was able to stick around. So, basically, we've found the first Chthonian Planet and never even knew it!

Next is Venus. It seems to me that Venus is not your normal terrestrial planet, but actually a cross between something Earth-like and a gas dwarf. Venus wasn't able to become a gas dwarf because of its distance from the Sun and small size.

Also, the design of our Inner Solar System seems a bit common in our stellar neighborhood. The Gliese 581 system has a Mercury analogue (Planet e), two Venus analogues (Planets b and c), an Earth analogue (Planet g/Zarmina), and a Mars analogue (Planet d). The positions of Planet c, Zarmina, and Planet d are quite similar to those of Venus, Earth, and Mars in our own system.

[magnemoe]

2 hours ago, ProtoJeb21 said:

I don't think our solar system is the normal we thought it was. And I don't mean that it is unusual; we've just mistaken it.

Take a look at Mercury. It may seem boring and ordinary, but there are some unusual things about it. For example, its abundance of iron, water ice on the surface for no reason, its eccentric orbit, and depleting hydrogen/helium atmosphere. Not to mention that, for some reason, there's lithium on the Sun's photosphere. Do you get where I'm going? I believe that Mercury is the remains of a gas dwarf that was shoved too close to the Sun. Most of its atmosphere was blown off and consumed, and some of the icy mantle was able to stick around. So, basically, we've found the first Chthonian Planet and never even knew it!

Next is Venus. It seems to me that Venus is not your normal terrestrial planet, but actually a cross between something Earth-like and a gas dwarf. Venus wasn't able to become a gas dwarf because of its distance from the Sun and small size.

Also, the design of our Inner Solar System seems a bit common in our stellar neighborhood. The Gliese 581 system has a Mercury analogue (Planet e), two Venus analogues (Planets b and c), an Earth analogue (Planet g/Zarmina), and a Mars analogue (Planet d). The positions of Planet c, Zarmina, and Planet d are quite similar to those of Venus, Earth, and Mars in our own system.

Some speculations that Mercury hit Earth and created Moon, If not it probably hit something else. Water from comet impact like the moon, water would either break down or deposit on sunless areas. 
 

[Geschosskopf]

1 hour ago, ProtoJeb21 said:

Take a look at Mercury. It may seem boring and ordinary, but there are some unusual things about it. For example, its abundance of iron, water ice on the surface for no reason, its eccentric orbit, and depleting hydrogen/helium atmosphere. Not to mention that, for some reason, there's lithium on the Sun's photosphere. Do you get where I'm going? I believe that Mercury is the remains of a gas dwarf that was shoved too close to the Sun. Most of its atmosphere was blown off and consumed, and some of the icy mantle was able to stick around. So, basically, we've found the first Chthonian Planet and never even knew it!

I dunno.  If Mercury formerly was a gas dwarf, it had to have passed through the region of the other inner planets, so there wouldn't be any other inner planets.  It does seem likely that a fair amount of stuff did fall into the sun, especially everything inside Mercury, however.

1 hour ago, ProtoJeb21 said:

Next is Venus. It seems to me that Venus is not your normal terrestrial planet, but actually a cross between something Earth-like and a gas dwarf. Venus wasn't able to become a gas dwarf because of its distance from the Sun and small size.

Again, I dunno.  I think it more likely that Venus was a fairly nice place until it suddenly had a planet-wide rash of volcanism, some of which might well be continuing today (possible hot lava flows detected last year).  But that all begs the question:  where does Venusian volcanism come from?  It doesn't seem to work like it does here, where it's mostly tied to plate tectonics.  Also, Venus doesn't seem to have much of a magnetic field so the workings of its core have to be rather different from Earth's.

 

1 hour ago, ProtoJeb21 said:

Also, the design of our Inner Solar System seems a bit common in our stellar neighborhood. The Gliese 581 system has a Mercury analogue (Planet e), two Venus analogues (Planets b and c), an Earth analogue (Planet g/Zarmina), and a Mars analogue (Planet d). The positions of Planet c, Zarmina, and Planet d are quite similar to those of Venus, Earth, and Mars in our own system.

It seems that the existence of Gliese 581 d and g has become highly doubtful lately.  Many now think they were false positives created by not factoring in the rotation of the star. 

[PB666]

https://www.nasa.gov/press-release/nasa-s-hubble-telescope-makes-first-atmospheric-study-of-earth-sized-exoplanets

 

[ElJugador]

About the planets we've actually found so far: I wouldn't rely on that data too much. All of our detection methods are naturally biased against smaller or more distant planets, so of course we wouldn't find as many. My feeling is that the real reason why our findings largely have super-terrestrials or close-in gas giants is simple detection bias.

Edited July 21, 2016 by ElJugador