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Is our solar system typical?

dasmiller said:
Our solar system should take some solace from the fact that there's not another one like it within a trillion miles. Literally, a tillion miles! (technically many trillion miles)


On the other hand, our solar system might be understandably miffed that we don't actually have a name for it. Our planet is "Earth," our galaxy is "The Milky Way," but our solar system is just "our solar system."

I mean, if we really cared, wouldn't we at least give it a name?
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Sounds worthy of a poll.


For that matter, what is the moon's name? The Moon? Saturn's moons get names.
 
quarky said:
Sounds worthy of a poll.


For that matter, what is the moon's name? The Moon? Saturn's moons get names.
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Our sun's name is "Sol". Our solar system (no capital) is the Sol System (capitalised).

Our moon is "Luna" (although she sometimes uses the name "Selene").
 
Pope130 said:
Our sun's name is "Sol". Our solar system (no capital) is the Sol System (capitalised).

Our moon is "Luna" (although she sometimes uses the name "Selene").
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Sure, I guess. But when there's about to be an eclipse of "Luna", its never really called by that name. Whereas, Europa is.

Shucks, even some of the asteroids have cool names.

I'd like the sun to be called "Sunny", and the moon called "Judy" and the solar system be called "Big Al".

I hope everyone's ok with that, and sorry for the topic drift.
 
Puppycow said:
It seems reasonable to me to assume that it is typical.

Not necessarily that life is typical, but that stars similar to our sun also have planetary systems that are similar to ours.

I was thinking that if a transit of Venus is so rare even though we are basically in the same plane as Venus, how rare it must be to see exoplanets transit in front of other stars.
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Its completely unreasonable to assume that our solar system is typical. Mainly because we've seen a ton of other solar systems and they don't look anything like ours.

We see lots of exo-planets transiting in front of stars - that's pretty much the only way to detect them right now and is the main reason that all the other systems we've detected tend to have huge jupiter plus sized planets in inner solar system orbits (orbits that in ours sytem would be inside the orbit of Jupiter).

As resolution gets better what's "typical" may change, but right now the standard solar system is a couple of really large gas giants in close orbits around the primary.
 
Agammamon said:
Its completely unreasonable to assume that our solar system is typical. Mainly because we've seen a ton of other solar systems and they don't look anything like ours.

We see lots of exo-planets transiting in front of stars - that's pretty much the only way to detect them right now and is the main reason that all the other systems we've detected tend to have huge jupiter plus sized planets in inner solar system orbits (orbits that in ours sytem would be inside the orbit of Jupiter).

As resolution gets better what's "typical" may change, but right now the standard solar system is a couple of really large gas giants in close orbits around the primary.
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kepler is finding that earth sized planets are much more common than jupiter sized planets
while youtube isnt considered proper evidence here the video from post 5 explains it better than i could and its a talk from someone from kepler
27.40mins to 39mins important part
"most are nearly earth size"
"galaxy is teeming with planets"
"170+ stars with multiple planets"
"smaller stars more likely to have smaller earth sized planets"
 
Agammamon said:
Its completely unreasonable to assume that our solar system is typical. Mainly because we've seen a ton of other solar systems and they don't look anything like ours.

We see lots of exo-planets transiting in front of stars - that's pretty much the only way to detect them right now and is the main reason that all the other systems we've detected tend to have huge jupiter plus sized planets in inner solar system orbits (orbits that in ours sytem would be inside the orbit of Jupiter).

As resolution gets better what's "typical" may change, but right now the standard solar system is a couple of really large gas giants in close orbits around the primary.
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You have to use common sense though. We know that there is a very strong bias to detecting hot jupiters because of the limitations of our methods. It is illogical to assume that the exoplanets we have detected are a representative sample.
 
ginjawarrior said:
kepler is finding that earth sized planets are much more common than jupiter sized planets
while youtube isnt considered proper evidence here the video from post 5 explains it better than i could and its a talk from someone from kepler
27.40mins to 39mins important part
"most are nearly earth size"
"galaxy is teeming with planets"
"170+ stars with multiple planets"
"smaller stars more likely to have smaller earth sized planets"
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Thanks for linking that video, btw. I'm watching it right now. Didn't get around to it last time.
 
I Ratant said:
There's no reason to expect anything significantly different... masses orbiting a primary in a more or less orderly manner.
It's all gravity.
Depends on what is at those other systems in terms of size, as to their detectability.
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Well, "We happened. It is statistically unlikely we are an oddity rather than common." itself is statistically questionable.
 
Puppycow said:
It seems reasonable to me to assume that it is typical...
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What leads you to believe this?


Okay, the reasoned argument goes something like - we should assume that our star is one of around 100 Billion stars in our galaxy out of an estimated 100 Billion galaxies in the universe; and the assumption should be that closer to the norm for that group of objects. That would seem reasonable, if all stars were the same. Looking out at the universe in a bit more detail, however, it seems that, depending upon how much detail we include in our inspection, that our star is fairly distinct. Not that I would qualify it as "unique," but not "typical" either.
 
quarky said:
Sounds worthy of a poll.


For that matter, what is the moon's name? The Moon? Saturn's moons get names.
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Technically, Saturn doesn't have a Moon, merely natural satellites. Moon is a proper noun that has been colloquially adopted to speak of the "Moon-like" natural satellites of other planets.

Saturnians might similarly speak of Mar's titans. (If there were Saturnians given to similar conventions - ;))
 
Puppycow said:
You have to use common sense though. We know that there is a very strong bias to detecting hot jupiters because of the limitations of our methods. It is illogical to assume that the exoplanets we have detected are a representative sample.
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I know there's a bias - that was the point of my saying that they are typical. Typical is based on what you see most often and that's what we see most often.

Except now it looks like detection is getting good enough to start seeing large numbers of smaller planets which is shifting the typical to that end.
 
Binary stars the size of our Sun are more common than singles so in that respect our solar system is not typical. They have more recently discovered that there are more single stars but this was only discovered when we started detecting more of the smaller cooler stars.

Astronomers Had it Wrong: Most Stars are Single
Stellar surveys found that more than half of all Sun-like stars were part of multiple systems. For more massive stars, like O- and B-type stars, the number was estimated to be as high as 80 percent...

...The catch, however, is that most stars in the Milky Way are not bright stars like our Sun, but dim, low-mass stars called red dwarfs.
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Something to keep in mind - when astronomers say "earthlike" or talk about multiple stars in a system, what they mean can be vastly different than what we as layman visualize based on our usage of those terms.

"Earthlike" can be the burned out hunk of a gas giant that's had its atmosphere boiled off because it orbits its primary closer than Mercury.

And Alpha Centauri is a trinary system but one of the stars orbits .2 ly from the other two.
 
Agammamon said:
I know there's a bias - that was the point of my saying that they are typical. Typical is based on what you see most often and that's what we see most often.

Except now it looks like detection is getting good enough to start seeing large numbers of smaller planets which is shifting the typical to that end.
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Well that is not what I meant by 'typical.'

I mean typical of what is actually out there, not just what we can see.
 
Puppycow said:
Well that is not what I meant by 'typical.'

I mean typical of what is actually out there, not just what we can see.
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Problem is, there is no evidence for it yet.

Worse, the known planetary systems without "hot Jupiters" -- which are a minority of known systems, but a large minority, -- are not similar to our solar system either. Their planets tend to have significant eccentricities, unlike "our" planets. So my answer to OP is: No, it is not reasonable to assume not our solar system typical. If anything, it is wishful thinking.
 
Let me phrase it a bit more strongly: The whole notion of Copernican Principle -- we live on a typical planet of a typical star in a typical galaxy, and the way things are here is the way things are (mostly) out there, -- is completely unsubstatiated wishful thinking. In fact, the middle part of the above statement is blatantly untrue despite having been repeated in countless textbooks -- the Sun is bigger and brighter than at least 96% of the stars in the Galaxy; it is most certainly not a "typical star". (Typical star is an M-class dwarf.)

Either life/multicellular life/intelligence require highly unusual conditions, or they do not. If the latter is the case, we will see many solar systems similar to ours, and Copernican Principle will be vindicated. If the former is the case, we will not see many systems similar to ours -- the fact that we are here only proves life-bearing conditions are possible, not that they are common.

In the Middle East occures a bizarre terrain called sabka. It is essentially a tar pit, covered by compressed sand. The sand crust is strong enough for people and camels to walk on, but collapses under trucks or tanks, miring them in tar like sabertooth tigers in La Brea tar pit. Sabka occures nowhere else on Earth. Some insect living on/in sabka could apply Copernican Principle to say "We are not special. Everywhere should be like it is here". And would be utterly wrong.

Does it mean laws of physics -- or even laws of geology, -- are different in Middle East than elsewhere on Earth? Of course not -- it just means that for sabka to exist, a set of rather unlikely conditions (each of them individually entirely within the realm of these laws) must come together. OTOH, sand in various forms exists just about everywhere. Wether our planetary system is akin to sand or akin to sabka is yet to be determined. And so far (weak) evidence points to sabka.
 
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