Is our solar system typical?

[Puppycow]

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.

 

[mikeyx]

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.

as opposed to what? Until we map out larger portions of the universe, the answer would be conjecture. Short answer, after clarification, we need more information than we have at the present time.

 

[Doubt]

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.

Although quite a few Astronomers have spent time telling us that our sun is average, the bad astronomer pointed out in his last book that our sun is really larger than most. So we are not atypical but not really average either thanks to solar gravity.

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.

IIRC, the Kepler mission finds planets by looking for the dimming that takes place when a transit occurs. But that also means it is much more likely to find a gas giant with a fast orbit rather than something small and rocky like Earth or Venus.

 

[Puppycow]

Although quite a few Astronomers have spent time telling us that our sun is average, the bad astronomer pointed out in his last book that our sun is really larger than most. So we are not atypical but not really average either thanks to solar gravity.



IIRC, the Kepler mission finds planets by looking for the dimming that takes place when a transit occurs. But that also means it is much more likely to find a gas giant with a fast orbit rather than something small and rocky like Earth or Venus.

That bias is really what i'm trying to get at. The planets we find are biased by the methods we use to find them. The methods are much more likely to find a so called hot jupiter than a Venus, Earth or Mars.

 

[ginjawarrior]

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.

i watched this talk about keplers discoveries the other day
27.40mins to 39mins he talks about how many planets they found very cool

 

[GreyArea]

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.

So far we have discovered about 200 candidate planetary systems using the transit method. And it's still early days yet.

Meanwhile, there are other methods of detecting planets. Results for the different methods can be found at the Extrasolar Planets Encyclopedia. This index page lists discoveries by method, including transits.

Although quite a few Astronomers have spent time telling us that our sun is average, the bad astronomer pointed out in his last book that our sun is really larger than most. So we are not atypical but not really average either thanks to solar gravity.

Earlier this year, Phil Plait wrote about some small exoplanets discovered around a red dwarf. He wrote in that post:

[This] shows that red dwarf stars can form and hold onto planets… which itself is important because red dwarfs are by far the most common kind of star in the Universe. They make up roughly 80% of the total number of stars! So finding multiple planets around one means, once again, planets are almost certainly common in the galaxy.

Here is a blog post with further links about just how common planets appear to be in our galaxy. There could be an average of one planet per star, and possibly an average of five per star. That means hundreds of billions of planets here, and possibly trillions.

IIRC, the Kepler mission finds planets by looking for the dimming that takes place when a transit occurs. But that also means it is much more likely to find a gas giant with a fast orbit rather than something small and rocky like Earth or Venus.

A smaller orbital period is also going to be noticed sooner. As Kepler is in space longer, it gathers longer runs of data on its target stars. We've had to wait to detect candidate planets that have orbits that take as long as Earth's. That's because we need to see the first two dimmings and then a third at the right time. Kepler started its search in May 2009, so those kinds of results should be coming in between now and 2013.

It's all very exciting.

 

[Toontown]

I think it is reasonable to assume that each solar system evolves according to it's peculiar initial conditions, which will vary widely based on small differences in the initial gas cloud. Thus, even if a sun similar ours is formed, the planetary system is likely to be quite different.

There are indications that many solar systems might feature one or two very large gas planets which have vacuumed up all the smaller planets which were initially formed. However, such gas giants are very likely to have multiple moons, and those moons might well be habitable to life of some kind.

 

[I Ratant]

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.

 

[Corsair 115]

Here is a blog post with further links about just how common planets appear to be in our galaxy. There could be an average of one planet per star, and possibly an average of five per star. That means hundreds of billions of planets here, and possibly trillions.

Wait, I thought most stars in the galaxy were part of multiple star systems, and that planetary formation around binary (or larger) star systems was thought to be difficult due to the gravitational influences and complications involved with multiple suns.

 

[Toontown]

Some gas giants have been detected which are surprisingly close to their suns. I wonder what Jupiter's ice moon Europa would be like if Jupiter occupied an earthlike orbit? I'm assuming mighty Jupiter would make a great bodyguard for a little water moon like Europa.

 

[rjh01]

One thing that puzzles me about our solar system is that there are no planets within the orbit of Mercury. Many of the planets found have an orbit that is closer to the sun that Mercury is.

 

[Corsair 115]

One thing that puzzles me about our solar system is that there are no planets within the orbit of Mercury. Many of the planets found have an orbit that is closer to the sun that Mercury is.

My understanding is that is thought to be due to gravitational perturbations between the planets of the system eventually causing some planets to either be ejected from the system or pushed into the star, and others (the so-called "hot Jupiters") to end up in a very close orbit around the star. Our solar system apparently has a stable assortment of gas giant planetary orbits and such gravitational disruptions haven't happened here.

 

[rjh01]

My understanding is that is thought to be due to gravitational perturbations between the planets of the system eventually causing some planets to either be ejected from the system or pushed into the star, and others (the so-called "hot Jupiters") to end up in a very close orbit around the star. Our solar system apparently has a stable assortment of gas giant planetary orbits and such gravitational disruptions haven't happened here.

That means that there are at least two possible evolutions of solar systems. I wonder if there are any differences in the stars themselves between the two systems?

 

[WhatRoughBeast]

One thing that puzzles me about our solar system is that there are no planets within the orbit of Mercury. Many of the planets found have an orbit that is closer to the sun that Mercury is.

Yes, but.....

A very large, very close planet produces a (relatively) large doppler shift in the star's output, and these are (relatively) easy tp detect. So, using spectroscopic data for searching is most likely to find exactly these systems.

Early days, yet.

 

[quarky]

The last time I looked at our solar system, I found myself saying "That's so typical".
Now I hope I didn't hurt its feelings.

Maybe our solar system doesn't have feelings.



(Typical.)

 

[dasmiller]

The last time I looked at our solar system, I found myself saying "That's so typical".
Now I hope I didn't hurt its feelings.

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?

 

[WhatRoughBeast]

Oh, come on.

It's the Sol system. I mean, it alliterates and everything.

 

[geni]

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.

There is no particular reason to assume that. In fact our current theories of planetary formation have a really hard time explaining the outer gas giants. Oh and please define similar in this context.

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.

It doesn't really matter. We can look at a lot of stars:

http://en.wikipedia.org/wiki/Kepler_mission

 

[Corsair 115]

That means that there are at least two possible evolutions of solar systems. I wonder if there are any differences in the stars themselves between the two systems?

My understanding is that it has to do with the distribution of the type of and relative masses of the planets in a solar system. Certain combinations are simply not gravitationally stable over the lifetime of the system. For example, having three Jupiter-like gas giants is apparently quite bad (based on sophisticated computer modelling of the gravitational interactions). Those three big planets' gravity perturb each other's orbits, and eventually this results in the entire system become orbitally chaotic.

Our system appears fortunate in that it has one big gas giant (Jupiter, 318 Earth masses), one moderately-sized one (Saturn, 95 Earth masses), and two small ones (Uranus and Neptune, 14 and 17 Earth masses, respectively). The result appears to be a solar system which remains pretty much orbitally stable over its lifetime.

 

[JoeMorgue]

Right now our understanding of extrasolar solar systems is sketchy at best and our understanding of our own solar system is still sorta half hazard. And trying to extrapolate information from a data set of one where your only about 80% of the value of the one piece of data you have and the only think you know about the other data sets is that they exist is... well not likely to be fruitful.