Posted on 07/30/2004 11:12:50 AM PDT by PatrickHenry
We could be alone in the Universe after all. The discovery during the past decade of over a hundred planets around other stars has encouraged many scientists to think that habitable planets like ours might be common. But a recent study tells them to think again.
Martin Beer of the University of Leicester, UK, and co-workers argue that our Solar System may be highly unusual, compared with the planetary systems of other stars. In a preprint published on Arxiv1 [footnote's link in original article], they point out that the alien planets we have seen so far could have been formed by a completely different process from the one that formed ours. If that is so, says Beer, "there won't necessarily be lots of other Earths up there".
Most of the planets around other stars, known as extrasolar planets, are detected from the wobble that they induce in their own sun's motion. This wobble is caused by the gravitational tug of the planet on the star. Because stars are much bigger than planets, the effect is tiny, and it is only in the past decade that telescopes have been sensitive enough to detect it.
Even then, the wobble is detectable only for giant planets, which are those about as big as Jupiter, the bloated ball of gas in our Solar System. It is not possible at present to detect planets as small as the Earth.
Jupiter is not habitable: it is too cold, and is mostly composed of dense gas. And it is unlikely that extrasolar giant planets would support life either. But astronomers generally assume that if they detect such a planet in a distant solar system, it is likely to be accompanied by other, smaller planets. And maybe some of the smaller planets in these systems are just like Earth.
This is what Beer and colleagues now dispute. They say that the properties of almost all the known extrasolar planets are quite different from those of Jupiter.
Hot Jupiters
There are 110 of these extrasolar planets, at the latest count, and they are all between about a tenth and ten times as massive as Jupiter. Most of them are, however, much closer to their sun than Jupiter is to ours: they are known as 'hot Jupiters'. They also tend to have more elongated orbits than those of Jupiter and the Earth, both of which orbit the Sun on almost circular paths.
Ever since Copernicus displaced the Earth from the centre of the Universe, astronomers have tended to assume that there is nothing special about our place in the cosmos. But apparently our planetary system might not be so normal after all. Is it just chance that makes Jupiter different from other extrasolar planets? Beer and his colleagues suspect not.
They suggest that other planets were not formed by the same kind of process that produced our Solar System, so they might not have smaller, habitable companions.
Different recipes
The planets in our Solar System were put together from small pieces. The cloud of gas and dust that surrounded our newly formed Sun agglomerated into little pebbles, which then collided and stuck together to form rocky boulders and eventually mini-planets, called planetesimals. The coalescence of planetesimals created rocky planets such as Earth and Mars, and the solid cores of giant planets such as Jupiter, which then attracted thick atmospheres of gas.
But that is not the only way to make a solar system. Giant planets can condense directly out of the gaseous material around stars, collapsing under their own gravity. This process, which generates giant planets with a wide range of orbital radii and eccentricities, does not seem capable of producing the rocky planets seen in our own Solar System, which is why it has generally been ignored.
Yet it might account very nicely for the known extrasolar planets. "It wouldn't surprise me if there are two different ways that planetary systems are formed," Beer says. But how can we know if that is the case? "Probably the best way is just to gather more observations," says Beer. Only then can we know how unusual we really are.
The Milky Way galaxy has approx. 100,000,000,000 stars and it's 1 of approx. 1,000,000,000 or so galaxies. So this nitwit is ready to conclude there are no more "earths" after a very crude form of investigation of 110 planets around 25 or so stars that at this point can ONLY, ONLY detect Jupiter-sized planets.
Utter rubbish from a pseudo-scientist who had to work hard to find something to write about.
There is only one data point. And that is us. All else is speculation. However, using probability, we can make some predictions. Thusly was born the "Drake Equation".
the book was
"the rare earth"
written by brownlee and another u of wash prof
an amazing book.
They go thru all the arguments why complex life is so rare. This is my solution to fermi's paradox.
Why is this surprising? If we're using gravitational anomolies to detect planets, of course it's going to be easier to find large planets that are close to their sun, because the effects of gravity are much greater.
Drake equation ping. I always go back and forth on this ....
When there are billions of stars in each galaxy, and billions of galaxies, it's kinda hard to believe we're unique.
Utter rubbish from a pseudo-scientist who had to work hard to find something to write about.
Well said.
Jupiter is not habitable: it is too cold, and is mostly composed of dense gas. And it is unlikely that extrasolar giant planets would support life either.
This type of thinking always amazes me. Yes, life that evolved on Earth has adapted to the conditions found on Earth, no surprise here. Would it be so surprising that life elsewhere in the universe would adapt to the conditions there?
Are We Alone (reason to ponder what makes the earth unique)
http://www.freerepublic.com/focus/f-news/1181928/posts
We've been over all this time and again on FR. Current detection methods select a highly specific (and probably highly unusual) sample which tells us little about Earth-like (or even Jupiter-like) worlds.
The idea that these close binary brown dwarf systems formed differently from our solar system in no way supports the title of this article, even if the idea is perfectly correct.
I think arminianism is arrogant and man centered and borders on man's will being a false idol...
I think arminianism is arrogant and man centered and borders on man's will being a false idol...
I am a Conservatie Baptist who says "Thank God for Martin Luther"
What is your opinion of the arguments made in "Rare Earth". The Drake equation only gives the upside, but doesn't seem to take into account the conditions that would preclude higher forms of life. For instance, the radiation conditions in the core of galaxies and in the arms of spiral galaxies are too high to allow the survival of higher life forms. That leaves the area between the arms for habitable zones in spiral galaxies, and stars only stay in between the spiral arms for extended periods of time if they are 1/2 the radius of the galaxy from the center of the galaxy. These factors alone remove several orders of magnitude from the number of possible stars that could sustain higher forms of life.
This seems too easy but "In the beginning God created the heavens (plural) and the earth (singular)"
IIRC, they have a common ancestor Tümuch Beer...
I thought our planets' orbits were "wildly elliptical."
Ding Ding Ding! We have a winner!
It's called a "selection effect" - the data sample looks biased towards hot Jupiters, but that's only because current detection technologies find those preferentially. Give it about 10 years and we will have much better data with the new surveys coming on line. Anyway, personally I find it amazing that we now know of 10 times as many planets OUTSIDE our solar system as IN it!
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.