Solar System Unique in Universe


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Profile fuzzylogic
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Message 14504 - Posted: 7 Aug 2004, 9:41:01 UTC

Solar System Unique in Universe
By Louis Achi with agency report

--------------------------------------------------------------------------------

The Solar System, a group of the nine planets dominated by the sun to which the Earth belongs, may be unique after all. This new astronomical insight was disclosed by British and U.S-based researchers, Thursday.

The discovery is seen to be significant despite the previous discovery of at least 120 other systems with planets, the astronomers said. All the other solar systems that have been found have big, gassy planets circling, too close to their stars to allow them to be anything like Earth or its fellow planets, the researchers said.

If that is the case, Earth-like planets will be very rare, the astronomers wrote in the latest issue of the Monthly Notices of the Royal Astronomical Society. "Maybe these other extrasolar systems contain only the giant planets," said Mario Livio of the Space Telescope Science Institute in Baltimore.

Livio and colleagues took a close look at what is known about the other planetary systems that have been discovered. "In (our) solar system the orbits are very circular. Most of the giant planets observed in extrasolar systems have very elliptical orbits," Livio said in a telephone interview with Reuters.



http://www.thisdayonline.com/news/20040807news17.html

Profile Richard M
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Message 14510 - Posted: 7 Aug 2004, 10:25:15 UTC

I find it hard to believe that they could come to that conclusion by looking at only 120 solar systems, considering the size of the universe.

;-)

TTYL
Richard

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Message 14515 - Posted: 7 Aug 2004, 11:12:25 UTC

yes, i agree.

Absence of evidence, is not evidence of absence.

ps Richard,

how do you get your stats to pop up like that in your post?

have i missed something?

Steve DeVeaux
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Message 14661 - Posted: 7 Aug 2004, 23:57:28 UTC

Exactly, Fuzzy.

The reason that most of the extra-solar planets discovered so far have all been gas giants on highly eccentric orbits is because they are by their very nature easier to detect (using the gravitational star-wobble technique) than more terrestrial-like planets.

It won't be long before technology improves to the extent that we can detect smaller planets in more sensible orbits... but we're just not quite there yet.

Is the earth flat? No.

Is the earth at the centre of the universe with the sun, stars and planets orbiting it? No.

Is our sun at the centre of the universe? No.

Do we live in the only galaxy? No.

Is our solar system the only one in the universe? No.

The answers to all these questions were once thought to be "yes", until certain people had a good think and used whatever new technolgy was available at the time. Just imagine what questions we could answer in the next 100 years...

Do extra-solar planets exist with similar physical and orbital characteristics as the earth?

Is the earth the only planet in the unbelievably huge, vast, and enormous universe capable of supporting life (intelligent, or otherwise?)

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Message 14668 - Posted: 8 Aug 2004, 2:23:38 UTC - in response to Message 14661.
Last modified: 22 Aug 2004, 3:27:24 UTC

I agree.

"We haven't bagged any aliens yet,
but I'm still optimistic in the long run.
Earthlings are just learning how to do this."
Dan Werthimer, SETI@home Chief Scientist

;-)


Clear skies from SETI Italia [/url]

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Message 14690 - Posted: 8 Aug 2004, 4:46:35 UTC

I doesn't mean that earth like planet doensn't exist
But it shows that it would be more rare then they thaught.
Actualy our solar system is in many way different then
those 120 observed. These 120 have similarities and our solar
system seem to be the exeption.

Who knows ! There might be just a few earth like planets in
our galaxy or in the entire universe !




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Message 14934 - Posted: 9 Aug 2004, 10:34:35 UTC
Last modified: 9 Aug 2004, 10:35:43 UTC

For scientists to say ya or nay right now would I think would be scientific suicide.

To say that our system is one of a kind? Pro or Con? Any scientist worth a dam will tell you simple. The physician data is just not there to make any conclusions at all.

To only look at 120 star's in a galaxy of billions and make that statement. I have only one thing to say to that ex-scientist. Burger King is hiring.

Get a good look at a 1,000,000 stars and say that? OK i will strongly consider the data. Hell even if you got a good look at 100,000 stars I would at lest consider your theory. To make that statement after only looking at 120? Some one wants to be a rock star = bad science!








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Message 14944 - Posted: 9 Aug 2004, 12:02:01 UTC
Last modified: 10 Sep 2004, 1:26:10 UTC

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Message 14967 - Posted: 9 Aug 2004, 14:39:29 UTC
Last modified: 9 Aug 2004, 14:39:55 UTC

some math nut did a algorithm on this subject. Do not recall the name.

The format was if 1% of 1% of the stars in our Galaxy having a earth like body around it. there would be at lest 1,000,000 planets with the change to have earth like life forms.






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Message 15002 - Posted: 9 Aug 2004, 18:36:17 UTC - in response to Message 14967.
Last modified: 9 Aug 2004, 18:42:31 UTC

> some math nut did a algorithm on this subject. Do not recall the name.
>
> The format was if 1% of 1% of the stars in our Galaxy having a earth like
> body around it. there would be at lest 1,000,000 planets with the change to
> have earth like life forms.

Mr. Frank Drake did one such calculation algorithm.. I posted it here just to give people something to think about ;)

You can find it in this thread if you're interested in taking a look at it. I originally found it from a book called "the science of x-files" or something similar.. I don't remember who wrote it though..

--J

edit: I looked it up and the book is called "The Science of the X-Files" by Michael White (ISBN number 0-09-918572-5)

edit2: typo

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Message 15014 - Posted: 9 Aug 2004, 19:27:40 UTC

You can play with the Drake equation at this site

http://www.area52online.com/sections/simulations/drake/Simulation5f.html


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Message 15049 - Posted: 9 Aug 2004, 22:18:23 UTC

Just a thought....

Using our current level of technology and understanding of the universe, i wonder how easy it would be to detect our solar system using the gravitational wobble technique? Well, I decided to spend a little time to find out.

OK, so some of this post might be a little complex for some, but the result is more important than the maths. Consider this quick calculation:

Simplifying our solar system to a binary system involving the two largest objects in it - the Sun and Jupiter. Under such a situation we can deduce that the ratio of the semi-major axes (a) of the orbits of the two bodies is equal to the inverse ratio of their masses, m, i.e.

(a[sun]/a[jup])=(m[jup]/m[sun])

now, the sun is 1047 times more massive than jupiter, i.e.

m[jup]/m[sun] = 1/1047 = 9.55e-4

and jupiter oribts at a distance of a[jup] = 5.203 AU

therefore a[sun] = 4.97e-3 AU = 745.5e3 km

So what I have just calculated is that during its orbit, Jupiters gravity causes the Sun to move almost 750,000 km with respect to their common centre of gravity.

Elementary trigonometry shows that observing this motion from only 1 parsec (or 206265 AU) away will cause a relative shift in the Sun's position of only around 5e-3 arcseconds.

Now I realise that I am not really up to date when it comes to the optical resolution of today's telescopes - earthbound or otherwise, particularly with the increased use of adaptive optics. However, I would wager that 5 milliarcseconds is rather beyond the detectability of even the best of todays instruments.

IF we had a star similar to our sun just a single parsec away, and
IF this star had a planet like jupiter orbiting at the same distance, and
IF by some marvel of modern technology we could actually detect movement of only 5 milliarcseconds,
THEN it would still take almost 12 YEARS of frequent observation to see just a single orbit. (Jupiter takes 11.86 years to orbit the sun, by the way)

Also, bearing in mind that the every star we know about is more than 1 parsec away, is it REALLY any surprise that we haven't detected any solar systems similar to our own yet?

I would appreciate any comment on this post, particularly if you think i've done the maths wrong :). It's been a while since I graduated with my Maths & Astronomy degree, so I am open to the possibility that I may have goofed somewhere :D

One wonders how someone can extrapolate the nature of every single one of the millions of other solar systems using a sample of just 120? - especially when the methods used to obtain the data for that sample favour a particular orbital characteristic.

Am I being simple here? Maybe I should check out this latest issue of MNRAS and see how these "scientists" came up with such guff.

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Message 15052 - Posted: 9 Aug 2004, 22:42:55 UTC - in response to Message 15049.
Last modified: 9 Aug 2004, 22:45:13 UTC

> Just a thought....
>
> Using our current level of technology and understanding of the universe, i
> wonder how easy it would be to detect our solar system using the gravitational
> wobble technique? Well, I decided to spend a little time to find out.
>
---- SNIP ----
> Also, bearing in mind that the every star we know about is more than 1 parsec
> away, is it REALLY any surprise that we haven't detected any solar systems
> similar to our own yet?
>
> I would appreciate any comment on this post, particularly if you think i've
> done the maths wrong :). It's been a while since I graduated with my Maths
> & Astronomy degree, so I am open to the possibility that I may have goofed
> somewhere :D

You're right that with today's technology finding solarsystems is really tricky.. but the wobbling of the star is not the only way to find planets orbiting them. I believe that better instruments and techniques are being developed to help to detect them..

I can't say if you've made a calculation error there somewhere as all that math is really beyond me ;) If you don't already know about the von Kármán Lectures over at JPL (Jet Propulsion Laboratory) I can recommend a couple of archived webcasts that deal with finding solarsystems around other stars, this one from june this year and this one from december last year. I found them really interesting :)

You need RealMedia player to watch them or then the Real Alternative Player which is propably better because it doesn't include all the unnecessary stuff...

--J

edit: the lectures last for a bit over an hour each, so broadband is definitely needed.

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Message 15199 - Posted: 10 Aug 2004, 17:57:10 UTC

thanks for the links :)

when i have time i shall look at those vids with interest :D

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Message 15410 - Posted: 11 Aug 2004, 10:12:38 UTC

indeed, to only base a conclusion from such a miniscule sample of data is laughable at best, perhaps the scientists in question need to take a few more lectures in scientific determinism before they make such fleeting statements.

Maybe they got into the brandy a little too much that evening...

Cheers

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Message 15454 - Posted: 11 Aug 2004, 13:43:56 UTC

Such a ludicrous and irresponsible statement (original thread I mean). Sorry to chime in on this so late, but I can't believe anyone in this field would have the nerve to make the assumption that we are alone in the universe, simply because we found a few gas giants out there. It stands to reason that the first planets we would find would be the biggest, right? Maybe they have assumed that all solar systems out there are seen on edge from Earth. There couldn't possibly be a solar system facing us head on, right? I think Livio should go find a nice desk job with some simpler problems to solve for a while. Just a thought.
"Freedom is the right of all sentient beings." - Optimus Prime

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Message 16231 - Posted: 22 Aug 2004, 1:58:52 UTC - in response to Message 14934.
Last modified: 22 Aug 2004, 2:00:19 UTC

> Get a good look at a 1,000,000 stars and say that? OK i will strongly
> consider the data. Hell even if you got a good look at 100,000 stars I would
> at lest consider your theory. To make that statement after only looking at
> 120? Some one wants to be a rock star = bad science!

Scientist didn't have to look at millions of galaxy to find out that they were
all "getting away" from each others...(not locally)

Look at it in another way. What we would say now if we had noticed that
those solar system were actually very similar to our ? We would say
I knew it, Life must exist everywhere, etc.

If you go on a 120 square meter beach and observe one sand grain every
square meter and realize that they are all "blue" you would assume that
chances are pretty good that the beach is "blue"

No scientist would affirm that this beach is blue untill more proof but
they have something to start with. Isn't it how science work ?

Saying that our solar system is unique is just too much but Saying that
according to current observations it appear to be rare is real science.

Regards
Marc



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Message 18971 - Posted: 29 Aug 2004, 1:54:12 UTC

Mr. DeVeaux's analysis is quite impressive and would be accurate if astronomers using the wobble method were looking for position changes. As I understand the method, they look for periodic shifts in the spectra of stars. Such shifts indicate that the stars have periodically changing velocities with respect to the Earth (i.e. they're moving back and forth). Since nothing astronomical just moves back and forth, this indicates some sort of orbital motion.

Now, let me pose this problem. If our hypothetical aliens were observing the sun (from however far away), how likely would they be to detect the presence of Earth?

Clearly, the first thing they would detect is Jupiter. What next? Of the nine planets in the solar system (moons won't have much effect, since their periodicity is the same as that of the planet they orbit), how many would be detected before Earth?

Using the method from Mr. DeVeaux's post, this essentially asking for how many planets is the ration of planetary mass with semimajor axis of orbit greater than for Earth (the sun's mass, of course, remains the same).

However, since what is detected is related to the velocity of the star, the period over which this change occurs is also relevant. Thus, the quantity above must be divided by orbital period.

In units of Astronomical Units * Earth Masses / Years, this is the same as asking for which planets is this quantity greater than 1.

In order, these are:

Mercury: .0897
Venus: .957
Earth: 1
Mars: .0872
Jupiter: 139
Saturn: 30.8
Uranus: 3.32
Neptune: 3.14
Pluto: .00035

By this analysis, it is clear that all of the gas giants would be detected before Earth. Also, there might be difficulty distinuishing between the effects of Uranus and Neptune and between those of Earth and Venus.

Just for comparison, the smallest planet yet detected is about the mass of Uranus, and orbits its star in 10 days.

My guess is that with current techniques we could detect Jupiter, but nothing else in our solar system.

Looking at this analysis, is there any doubt as to why most of the planets we've detected are massive and close to their stars?

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Message 19061 - Posted: 29 Aug 2004, 9:40:02 UTC

For nothing more than playing devil's advocate, let us first take into consideration that life, planets, stars, everything is completely random. Let us then assume this is fact. IF the previous statement is true then there is a possibility, (however unlikely that I personally believe) that our solar system is 100% unique. Odds are against it, but even the 50 to 1 horse wins from time to time. Which time is it for the Universe?

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Message 19087 - Posted: 29 Aug 2004, 12:24:27 UTC

Uniqueness does not mean that another planet with life can not exist. Just as our planets, moons and asteroids are different, so probably are other solar systems, each unique in their selves.

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