We're no longer biggest star system!

AnTiFreeze3

I remember watching something on the Science channel episode about astrophysicists who were theorizing how the solar system, and the planets inside of it, were formed.

Apparently, an amazingly long time ago (remember, I watched this on TV about a year ago, I can't remember the numbers, sorry) we had way more planets than we do now.

I was watching it while also surfing the web and eating, so as far as I could tell, a lot of the planets crashed into each other.

Forgive me for this being really vague, but basically, some astrophysicists theorize that our solar system had several times more planets than we currently do, back when it was young and planets were just forming.

TGlad

Yeah but 'known and factual' in astronomy is statistical. We 'know' a planet exists because its sigma is greater than 4 (or whatever). It is possible to 'know' a star system to has > 100 objects in it (with sigma > 4), without there being a sigma>4 on 100 individual objects.
To take it to the extreme, we know factually that certain systems have accretion disks made out of millions of particles, but we don't need to verify individual grains to be able to state that fact.

Anyway, I've no idea what the theoretical planet limit is, or if there is one. The definition of planet is a bit arbitrary, so a bit hard to theorise about I would have thought.

mfb

Well, known objects can be counted. You can store the orbital parameters in a database, and predict their future positions (with an uncertainty). If you could detect meter-sized objects in the asteroid belt, you would get a really large number of them. However, this would just increase the number of known objects.

Well, observing every dust particle is not useful, of course, but our solar system wins for every lower bound which is at most close to the moon in mass or diameter.

TGlad

Counting the number of objects in a star system is like counting craters on the moon, or rocks in a pile of rubble. The closer you look, the more you find, the number is effectively infinite as you find smaller and smaller ones all the way to the microscopic level.
You could impose a lower bound, but that is artificial. Anyway here's some thoughts on that subject- http://www.fractalforums.com/mathema...-great-britain.

DaveC426913

The fact remains that the number of known objects in our system exceeds the number of known objects in any other system, with or without any bound.

TGlad

I agree.
The discussion being that 'most known objects' is different from 'known to have most objects'.
Our solar system will have the most known objects for the foreseeable future. But it is quite likely that another star system will be known to have most objects.. in the next few decades.
Anyway, enough talk from me, I'm not an astronomer.

ImaLooser

Well, what if you have two rocks that are the same size? That would be a double planet.

I think it is OK to think of the Moon and Earth as a double planet, because the Moon is proportionally large compared to all other moons. I have seen this elsewhere as well.

How about this: it's a double planet if the center of mass is not inside any of the objects. With the Earth/Moon system it is. So the Moon is a moon.