Posted on 07/03/2002 9:03:47 AM PDT by RightWhale
Scientists estimate 30 billion Earths
By Dr David Whitehouse , BBC News Online science editor
Astronomers say there could be billions of Earths in our galaxy, the Milky Way.
Their assessment comes after the discovery of the 100th exoplanet - a planet that circles a star other than our own.
The latest find is a gas giant, just like all the other exoplanets so far detected, and orbits a Sun-like star 293 light-years away.
Scientists say they are now in a position to try to estimate how many planets may exist in the galaxy and speculate on just how many could be like the Earth. The answer in both cases is billions.
Virtually all the stars out to about 100 light-years distant have been surveyed. Of these 1,000 or so stars, about 10% have been found to possess planetary systems.
So, with about 300 billion stars in our galaxy, there could be about 30 billion planetary systems in the Milky Way alone; and a great many of these systems are very likely to include Earth-like worlds , say researchers.
Better grasp
The 100th new planet circles the star HD 2039. It was found by astronomers using the Anglo-Australian Telescope as part of the Carnegie Institution Planet Search Program.
The Jupiter-sized world circles its star every 1,210 days at a distance of about 320 million kilometres (200 million miles).
Astronomer Dr Jean Schneider, who compiles the Extrasolar Planets Catalogue, told BBC News Online: "The 100th planet is symbolic and important.
"The first discoveries concentrated on short orbital periods because of the limited timebase of observations. Now, we are learning more about the statistics of long orbital periods and know to what extent our own Jupiter is exceptional or not."
New telescopes
With the new world, astronomers say that they have just about finished surveying all the Sun-like stars out to a distance of 100 light-years from Earth.
Current planet detection technology - based on the "wobble" induced in the parent star by the gravitational pull of the orbiting planet - can only detect worlds about the mass of Saturn or larger. Earth-sized worlds are too small to be seen.
But even in this "biased" survey of giants, the smaller worlds predominate - which makes astronomers think that Earth-like worlds do exist. They may even be as common as Jupiter-sized exoplanets.
And if stellar statistics gathered in our local region of space are applied to our galaxy of 300 billion stars, then there may be 30 billion Jupiter-like worlds and perhaps as many Earth-like worlds as well.
Astronomers will have to wait for a new generation of space-based telescopes incorporating advanced detectors before they can detect Earth-sized worlds orbiting other stars.
But you could find a diamond jewel in a bucket of sand, and that could represent earth. We have found an earthlike planet! In fact, it's right here.
If they lack these basics, don't worry. They shall have Blockbuster as soon as we get there.
Another thing about this article: They are basing the estimate on there being 300 billion stars in the Milky Way. The more common estimate is 100 billion, I think, though I've seen estimates as high as a trillion. And that is only one of the factors that contributes to the uncertainty in this guessing game. In other words, 30 billion is a point estimate with a huge margin of error. Whenever your error bar includes zero, your estimates don't tell you much.
I think we're going to find many Earth-size planets out there, but I doubt we'd be able to actually live on many of them, if any, without massive terraforming.
Life, yes. Rock-eating bacteria, mainly.
We, our descendants, probably will choose to stay in the interstellar ships, dropping down to planets to do some natural resource extraction from time to time.
'Three-Hundred Million' just isn't a very large number in the universal scheme of things, even in light years. It's a huge distance in light years, but even that distance is comparable to a walk to the corner market in a city the size of Manhattan Island, in a state the size of New York.
There could be a near-replica of Earth within our Milky Way galaxy and we wouldn't know about it any more than a solitary bacterium in your mouth would know about another bacterium in a kangaroo's mouth in the Australian outback.
... And in just our galaxy, a bacterium in your mouth might as well be sitting directly next the bacterium in that kangaroo's mouth when compared to the travelling distance just from our Sun to the nearest star.
One look at the Hubble Space Telescope's 'Deep Field' pictures of the edge of the visible universe is both mind-blowing and sobering to those that can appreciate large numbers.
One of the most awesome sights. There are a lot of stars in the sky. We can see perhaps 4000 individual stars on a good night. The Milky Way, the galaxy we are in, has billions of such stars. The Deep Field image knocks it home that there are as many galaxies as there are stars in the galaxy. Maybe more.
If we ever get off this mudball, we can go for a long time without worrying about running out of places to go and things to do. A very long time.
So why can't the enviros construct a spaceship of their own and go "save" one of the other earths? That way, they'd leave us alone...
Exactly!
Get your terminology correct, you dunsel (g)
And always remember who your Drillthrall is!!!
I'd be happy if we could get off this planet and leave the Musli and enviros to have the earth and screw it up any way they want.
Avoid Planet LV-426 at all costs. A recent terraforming project failed there, with the loss of about 150 or so lives, and the destruction of the terraforming unit by nuclear explosion. Rumors say that the unfortunate ending was caused by bizarre alien superpredators with two-generation reproductive cycles.
Wrong! On July 4th, 1996, the Earth was narrowly saved from alien invasion by a nerdy cable repairman who uploaded a computer virus from his laptop to the alien mothership, thus destroying the alien force shields. Impossible to communicate? Ha!
Not sure your vision is what I'd sign up for, but ain't Liberty grand! What will you name your asteroid? My best to your friends and family, may you all enjoy a happy fourth!
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