Posted on 03/31/2005 4:27:51 PM PST by Heartlander
Five Out of Five Researchers Agree: Earth's Solar System Special
By Sara Goudarzi
Special to SPACE.com
posted: 31 March 2005
NEW YORK -- Though researchers find more and more distant planets revolving around alien suns, the discoveries highlight that Earth and its solar system may be an exceptionally rare place indeed.
That was the consensus here Wednesday evening among five planetary science experts who spoke at the 5th annual Isaac Asimov Memorial Panel Debate held at the American Museum of Natural History.
Neil DeGrasse Tyson, the Frederick P. Rose Director of the Hayden Planetarium, moderated the informal discussion. At issue was whether our solar system is special, why it looks the way it does, and how others thus far detected differ. The debate took place between theoretical and observational scientists on the different aspects of detecting and categorizing alien solar systems. About 700 people attended the event.
Prior to the discovery of planets around stars other than our sun in the 1990’s, scientists thought that alien solar systems must look something like our own. They presumed that just like our solar system, there would be small rocky planets like as Earth close to their host stars and large, low density ones a little farther out. But what they discovered were solar systems unlike ours with big Jupiter-like planets close to their host star.
Of the 150 alien planets found, none of them resemble our own. “So maybe it’s not the enigma of other solar systems, it’s the enigma of our solar system,” Tyson said in opening the debate.
The trouble with understanding planets outside of our solar system is that they are typically hard to see because of their bright host star, explained Paul Butler, co-discoverer of two-thirds of the known extra solar planets. However, even with these constraints, indirect methods allowed scientists to detect planets as massive as 300 times the Earth and ones as small as 15 times the mass of the Earth outside of our solar system,
As it turns out, the mass of a planet is its most important characteristic for comparative astrometry, the measurement of star positions. The mass determines if a planet is a gas giant or a rocky formation. “If it’s a rocky planet, like Earth or Mars, then one can focus on its atmosphere and learn more about its characteristics,” said Fritz Benedict of the University of Texas.
Typically, the most sought after characteristic of a planet is its habitability. A habitable planet has liquid water on its surface, explained Margaret Turnbull of the Carnegie Institute of Washington. Thus far, 90% of all detected alien planets have host stars that can flare and sterilize the surface of the planet. Furthermore, planets, which are that close to their host star, would be in a synchronous orbit. This means that only one side of the planet would face the host star and all potential water on that side would evaporate and go to its “dark” side.
While theorists such as Peter Goldrich of Caltech and Scott Termain of Princeton University did not predict finding solar systems with Jupiter-like planets so close to their orbit stars, they did theorize their dynamics. As early as the1980’s, they showed that planets such as Jupiter could be very mobile, moving rapidly, and changing angle and momentum to switch orbits and migrate closer to their parent stars. “Planetary system is not static, it’s continually processing. Orbits jiggle around,” said Termain.
At the end, all agreed that there are still discoveries to be made before we can know if our solar system is special or unusual amongst the universe. But speculations varied.
“I have a problem referring to our own solar system as unusual, because we haven’t done that experiment yet, we haven’t searched for our own solar system yet,” said Turnbull Thus far, the kind of data obtained and the type of observations made are tuned to search for Jupiters and not Earths, therefore that’s what we find. “The experiments were designed for that,” she explained.
But with the vast majority of the alien planets found in eccentric orbits, Butler has a different view. “I think with the data at hand, we can say that our solar system is rare. Eccentricity dominates,” said Butler. “It’s just a matter of how rare we are,” he added.
And Benedict agrees. “The older I get, the less likely it seems to me there’d be a bunch of places like our solar system,” he said. Or as Tyson added, “There’s no place like home.”
I thought every solar system was special.
"I thought every solar system was special."
It certainly wasn't very PC to single ours out. How must that make other solar systems feel?
March 31, 2005 - Comet Bradfield or Venus Transit?
And you're welcome.
When you consider the millions/billions of galaxies each with millions/billions of stars the possibility of Earth [sic--more properly Terra] being unusual becomes a little difficult to believe...the odds are simply against it.
Interestingly non-believers only think about odds when it comes to non-observable assumptions ...
I remember when many scientists felt that solar systems with planets weren't very common. Now we're discovering them every day--seems it's more common then expected years ago. They were wrong about the odds then and, IMHO, they are still wrong about the odds now.
It sure does in my circle of friends.
God is perfect. For some reason our understanding for the real odds for life on earth increased proportionally to the power of telescopes. It's called status quo understanding the basics
This would be like calling up one random person in Peru to get the average political opinion here on the entire world.
What about the researcher who knocks himself out swatting a fly?
D'OH!
I'm sure that, if there are any other life supporting systems, they all think that they are special.
Circular reasoning... since no one knows (or, in my opinion, will ever know) how many other such systems exist.
I used to think exactly that; in fact, forty years ago I wrote a long school paper arguing exactly that. Indeed, that was Carl Sagan's argument.
However, it turns out to be a totally fallacious argument. Sagan posited two parameters (you mentioned only one) for the existence of life on even one planet anywhere in the universe. But scientists have been looking into that, and now they have over 200 (and rising rapidly) such parameters, all of which must be exquisitely fine-tuned for life to exist anywhere. The true odds of even one planet being able to support life anywhere in the universe are (very conservatively stated) much less than one in 10 to the 40th.
I'll mention just two examples:
* If earth were just 1% closer to or farther from the sun, the water cycle would break down and life would not exist on earth. (Actually, this is two parameters: not only must earth's orbit be the right distance, but it also must be nearly circular.)
* If earth's mass (i.e., its gravity) were 2% larger or smaller, life would not exist on earth. You've noticed that water vapor (H2O, atomic weight 18) rises as clouds. If the earth were slightly smaller, those clouds would simply keep on going, higher and higher, until they were in space. However, if the earth were slightly larger, then methane gas (CH5, atomic weight 17) would not escape into space as it does, and we would all suffocate. Methane gas is the technical term for flatulence--not a pretty picture, is it?
There are over 200 parameters like that which must be right for life to exist on a planet. These factors work on the extra-galactic level, the galactic level, the solar-system level, and the planetary level.
Don't take my word for it--see for yourself:
http://www.reasons.org/resources/apologetics/index.shtml#design_in_the_universe
not only that but if we didn't have a moon at its very distance from Earth and size, life would not exist. "I Am" did it right the first time. Did he do it more than once? That is the question. I don't believe he did, myself.
The true odds of even one planet being able to support life anywhere in the universe are (very conservatively stated) much less than one in 10 to the 40th.
The mockers might post something like;
Well, isn't that *extra* special?
Yeah, it's "special", all right. What is more amazing is the spirit.
Shared, given from on high, given to (for?) mankind. What a gift!
Both terms are very old, just different languages, and both mean the same thing--this place here. Earth is not capitalized unless it happens to be the first word in a sentence or in a headline or title.
Gee, if the nine Supreme Court Justices agree, I guess it's unanimous.
...which is just another way of saying none of them are. (apologies to The Incredibles)
Disclaimer: Opinions posted on Free Republic are those of the individual posters and do not necessarily represent the opinion of Free Republic or its management. All materials posted herein are protected by copyright law and the exemption for fair use of copyrighted works.