Questions about the Sun and other stars

[tryme]

If the sun is our closest star does that mean other stars could be strong enough to support other planets like the sun does to us? If no then why is the sun called a star if it is unique in this?

[bish]

Other stars can support planets like Earth, but we've yet to find any just like Earth. So far we know of 297 stars that have planets orbiting them. We are getting closer as technology advances, and my opinion is that we will find Earth like planets. This website is good PlanetQuest: Exoplanet Exploration

[AstroTiger]

The Sun is just a star like any other, whether it hosts inhabited planets or otherwise.

Over the past 20 years our ability to see further into space has increased tenfold.

At the rate we are going, we will be able to "see" many of these exo planets.

Just a matter of time :-)

Also its not so much as down to if the Sun is strong enough to have a solar system.

Its more down to the secretion disk which orbits the star and if this contains the material for planets to form.

As we know from our own solar system, not all planets would go on to have life form on them :-)

[tryme]

Oh right so basically pretty much any one of the stars out there could support a solar system but there just isn't any planets like earth orbiting them? Is that true?

[crovax]

Yeah, any of the stars can support planets and some of those planets may be earth-like. It's just our technology is not sophisticated enough to detect them. IMHO taking into consideration that epic amount of stars in the sky there certainly are some earth-like planets with life.

[ollypenrice]

It is only for historical reasons that we have two words, 'sun' and 'star.' It is just that when the language was evolving we didnt know that the sun WAS a star. It's often like that in science; we have all sorts of names for electromagnetic radiation. We call some of it light, some of it radio, some of it X ray, some of it Gamma ray...but it is all the same stuff with changes in wavelength. We just didn't know that while we were dicovering and naming it all.

Planets form in 'accretion discs' around young stars, rather like the rings of Saturn to look at, probably. The big bits in the disc find each other by gravitational attraction and blend together into bits big enough to call planets. The modern definition of a planet is that it be a massive enough lump of matter to pull itself into a more or less round shape, so Pluto is out!

Olly

[ashenlight]

Interesting thread guys, I've popped it into the 'Physics, Space Science and Theories' section for you, should get more air time off people who are really interested in this kind of stuff

[tryme]

Thanks for the help guys. Just wanted to say though none of the stars in our solar system will have planets orbiting them right? Other wise we would see them in telescopes etc surely?

[crovax]

It seems that you're confusing some terms.

Solar System is basically Sun, 8 planets and may be all the tiny stuff (asteroids, etc) we have near by. I don't really know the exact definition so I don't know if the tiny stuff counts... So the only star in the Solar System is Sun and it has 8 planets. I guess you mean the closest stars to the Sun? I don't know if those have planets but I am sure we don't have any chance to view them in our scopes. This is possible with super-expensive Hubble-like telescopes and as far as I know the current technology is able to detect only huuuuuge exo-planets (planets that belong to other stars). About the size of Jupiter.

Also some of them are detected not by direct observation. As far as I remember from some documentary the technique can be compared to the following. Imagine a guy that holds a rope and has some heavy object on it. If he starts rotating it around himself, you can tell that he does this even if you don't see the object he rotates. The similar thing works with stars. A star with planets acts in the same way and very by precise measurments of its movement we can tell that the star has planets.

Another way involves the detection of the planet when it passes between us and its star. Of course this requires super sophisticated tools too.

[JamesK]

The tiny stuff does count... the solar system spreads way beyond the orbit of Neptune. To clarify:

A Star is mass of superheted material, which creates energy through the process of converting Hydrogen (an element) into Helium (another element). Our Sun is a Star. Some Stars form a system of two or more stars gravitationally linked to one another.

The Solar system is made up of all the Planets, Dwarf Planets, Asteroids, Comets, and other Random Rocks that are graviationally attracted to the Sun. Many, some say most, Stars may have systems like this. Nearly all of them probably have some sort of rocks orbiting them.

A Galaxy up of many stars, each with their own systems, some possibly without them. Galaxies are clumps of stars, massive groups of them between the massive empty bits in the Universe.

Sorry if that seemed a bit partonizing to you, it wasn't meant to be... just clearing some things up, semed you were a bit confused with your terms.

[legion48]

....Its more down to the secretion disk which orbits the star and if this contains the material for planets to form....

I think you meant accretion disk.

[crovax]

Yeah, and when you look at the sky and see all that spectacular amount of stars, you see only our own galaxy - Milky Way. Milky Way is a spiral galaxy and that big white belt of stars are spiral arms, core, etc...we're just looking from inside and that's why we see it like that. So when you locate Andromeda for example you're looking at another huuuuge heap of stars the size of our Milky Way. And if you think of all hundreds and hundreds of other galaxies that have and have not yet been discovered, you realize that life certainly must have developed somewhere.

[tryme]

Oh sorry guys when I said solar system I meant other solar systems. I'm assuming you can say other solar systems? lol Astronomy is such a confusing subject at times!

But to clarify what i'm saying...The stars we see in our night sky wouldn't have planets orbiting them or we would have found them by now?

[crovax]

I guess Solar System term can be used only for the system of our star - Sun. And regarding all other stars and their systems...well it depends on what you mean when saying "we". If you mean "humanity", then yeah, we are capable of detecting their planets. And those methods are from being ideal so we detect only huge planets and miss all smaller ones. And if you mean amateur astronomers, then I am afraid we can have a look at exo-planets via internet.

By the way you can have a look at this

Extrasolar planet - Wikipedia, the free encyclopedia

There is some usefull info on already discovered exo-planets and on the methods used to do that.

[tryme]

Yeah I was having a look at that earlier lol. thanks for helping me out on this means alot as I really do want to find out as much as possible.

Another point to raise is that is it likely there will be life on these smaller planets that we are likely to miss or is it more likely they will be on the larger planets that we are less likely to miss?

[bish]

I think the large planets that we are finding are gas giants like Jupiter. I imagine that there is more likely to be life ('as we know it') on the smaller rocky planets that are more Earth like, provided they are a suitable distance from the star - the 'goldilocks zone'. As you can tell, I'm no expert on astrobiology.

[tryme]

So just to clear this up once and for all. All the stars in our night sky COULD support life but we have not found any planets to be orbiting them? Is this because they are so far away? Why do they look like they are so close together?

I have recently been reading into saturns moons, titan and encellydus and apparently they are the closet thing we have found in our solar system that could harbour some form of life on them weather it be bacteria or something else.

[JamesK]

We have found several planets orbiting stars in our galaxy. Most of them have been "ruled out" of supporting life, because they are too close or too far away from the star in question, and therefore too hot or cold to support life. To me this is rubbish - how can we know the nature of life light years away, it might not even be DNA based, in fact the laws of probability would tell us this is unlikley. Intelligent habitants of that planet may think our planet inadequate to support life with it's unthinkably freezing temperatures, corrosive oxygen atmosphere and toxic water flows. However, we believe that titan, encellydus and some planets orbiting other stars have the right conditions for life as we know it - but we have not actually detected any non-earth-based life forms thus far.

[arad85]

So just to clear this up once and for all. All the stars in our night sky COULD support life but we have not found any planets to be orbiting them? Is this because they are so far away? Why do they look like they are so close together?

I think it more correct to say that all the stars may support life, but we have not found any evidence of it because we don't have good enough equipment to detect it.

As to your question of why they look so close - there are two reasons for that.

- They may well be close - there are a number of stars which are clustered together - Pleiades for example. When I say close, I mean relatively close compared to the distance they are away from us

- They may well lie in nearly the same direction away from us - that is, one may be 10 light years away, the other may be 30 light years away - they just happen to lie on near enough the same line of sight.

You need to be thinking relative size and distance here to start to comprehend things. Our nearest star is 4.3 light years away - that is around 300,000 times further away from the Sun than we are. Putting that into scope - suppose I was on a planet orbiting that star (proxima centauri) looking to find life on our Sun. If I represented our Sun as a small but bright dot of light 1km away, the earths orbit would be around 3mm radius and the earth would be a dust particle of size 0.0002mm orbiting around that dot. Do you think that would be easy to spot at 1km?

Is it any wonder we're having difficulty finding anything out there?

[crovax]

Yes, the best we can do is to say "this star has higher chances to have life than this star". I heared somewhere that scientists can detect different elements and molecules in the atmospheres of exo-planets. The same source where I found this told that scientists detected methane in some distant exo-planet. Methane is associated with earth-like life so all we can do is to give that planet a bit more chances to have life in comparison to other planets. But of course that can be some toxic hellish planet without any signs of life. So as for now we don't have any exact info.

By the way this made me wonder about the types of huge planets...do they all have to be gas giants? We have 4 huge planets in our system and all are gas giants. Why can't huge planets exist as a solid Mars-like objects?

[bish]

I think we now have the technology to discover planets around the size of the Earth (with Kepler) and establish some of the chemical make up, which would tell us that a planet is capable of supporting life. I'm not sure how close we are to actually being able to 100% prove that life exists elsewhere unless it is found through exploration of our solar system on, for example, Titan or Enceladus, as previously mentioned.

I'm not sure if there are definite limitations as to the size of rocky planets but would like to know the answer.

[tryme]

Thanks for all this help guys. I'm learning alot.

[Astro_Baby]

The analogy of distance I remember is that if the sun were the size of a football the Earth would be the size of a frozen pea 30 yards away. The next nearest star woul be 14,000 miles away on that scale.

The sizes of this stuff are so hard to get your head around. You may like this - its a vidoe of comparative stellar sizes - no matter how many times I see it it still leaves me amazed.

[crovax]

OMG, that video is very very impressive. I imagine what kind of black holes those stars will someday give birth to.

By the way I've just watched documentary about Cassini-Huygens on National Geographic and they say that those probes have detected a lot of molecules that may mean life on Titan. Also they think that the current state of Titan reflects Earth's state billions of years ago when life was starting to appear.

[JamesK]

That is one awesome video.