Scientists estimate 30 billion Earths

bbc ^ | 3 Jul 02 | Dr David Whitehouse

[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.

[Mark Bahner]

"There might be other planets about the size of earth, but none of them, not one, would be like earth in any other way. Don't expect meadow-fresh air, nor mild seasons, nor lake trout."

How do you know what to expect? I expect water, with life in that water, and land, with life on that land. Beyond that, it's pretty difficult to say, since we haven't yet observed life on any other planet. (I'm expecting we'll find life on other bodies, even within this solar system.)

[HardStarboard]

Thinking on this further - each of the Hollywood types can have their own planet and be the sole inhabitant. I nominate Barbara Striesand and Tom cruise as the first
recipients of their own "Personal Planet" and authorize my tax money be spent to get them "home".

[laredo44]

We don't actually need planets to live in outer space. Think about it: If we can build starships that take 1000 years to get anywere, we will have essentially built our own worlds.

I've read the asteroid belt has enough material to construct the equivalent of 1000 earths, if we make them hollow, live on the inside, and produce a simulated gravity through rotation.

[Savage Beast]

Maybe you're right. Do you suppose that's why so many people act like alpha-rats? They feel cramped?

[patriot_wes]

and a great many of these systems are very likely to include Earth-like worlds , say researchers......and..... Earth-sized worlds are too small to be seen......

and we pay these people millions in tax dollars to come up with these brilliant commentaries.....argh!

[RightWhale]

wait a few years

It's going to be interesting during the next ten years if NASA and ESA get their earth detectors launched. Who knows what might be found. There are some good ideas being converted to hardware, so if there is something out there it seems there is a good chance it will be spotted. We're counting chickens before they hatch at this time.

[Grig]

"So how can they possibly make the claim of earth-like planets? EVERY other
planet found has been a gas giant. "

At the very least, what they have found confirms the current theroy on solar system formation.

The theory has the result of predicting that large gas giants will be formed in the outer orbits and smaller earth-like planets formed closer in, (Pluto is probably a captured comet) the large gas giants also help sheild the inner planets from comets and asteroids making it easier for life to begin and continue on them.

It is also theorecticly possible for more than one planet that can support life to orbit one sun.

[RightWhale]

I think so. Like Danl Boon, we need elbow room.

[mad_as_he$$]

humm well the way I was taught is that all other souls will be saved because of the great experiement (here) between good and evil. God was calling Satan's bluff. So we live with sin.

[RightWhale]

Asteroids, of course, need power if you want to live there. But aside from that, how harsh would it be to live on or in a 20-mile diameter asteroid with a few good friends and family and that is outfitted with all the stuff a person needs?

[denydenydeny]

For an opposing point of view...

[The KG9 Kid]

If the number you pick would be anything but 'zero', that would be immensely significant.

[WyldKard]

Suggesting that there could be life out there and planets we might like is like telling Columbus that streets in America are paved with gold. Such an idea might cause exploration and the king to open the kingdom's coffers, but the reality will be far different. False hope. How is the King of Spain doing these days?

Columbus' eventual exploration of the New World yielded an amazing wealth of riches, and eventually helped lead to the birth of our great Nation. think you have just made the case for MORE space exploration....

[The KG9 Kid]

"... If you pick up 300 million grains of sand off a beach, what are the odds of even one jewel-quality diamond being in there?"

Not a relative analogy, I don't think; A beach would be the last place to look for a natural diamond.

Might be an OK place to look for a lost diamond that fell off a wedding ring though.

300,000,000 grains of sand isn't much more than a bucketful anyway.

[denydenydeny]

A while back I came across a study that I now really wish I could refer back to for this response. It took into account the unique aspects of Earth's cosmological history to conclude that the odds of another earth may be very small indeed.

See the Scientific American article linked in my # 51.

[fporretto]

This article reminds me of the reason I headed into astrophysics as a young man. You can make claims like these, as dramatic as you like, and no one can falsify them.

Sure, there could be 30,000,000,000 Earths in the Milky Way. But who's counting? What would cause a planetary body to qualify as "an Earth"? Would it have to be compatible with Terrestrial life, or just have a rocky surface, an oxidizing atmosphere, and liquid water? This sort of thing makes "political science" look positively scientific, by comparison.

Personally, I won't be satisfied unless they have HDTV and Blockbuster Videos on every corner.

Freedom, Wealth, and Peace,
Francis W. Porretto
Visit The Palace Of Reason: http://palaceofreason.com

[apologist]

Well, lets think for a moment. Considering that that orbits somewhere between that of Earth and Mars would be optimal, considering that the most abundant substance in the universe is hydrogen and the prevalence of low end atomic table substances, I submit that water is plentiful, as is carbon.

I suspect the universe teems with life.

Food for thought:
Probability for a Life Support Body

[far sider]

Well, I think there may be validity to that (even though it's really just religious speculation-it's not in the Bible). But I think that it's more likely the souls that would benefit from this "experiment" (which I think of as more of a "demonstration" since God already knows the outcome), would be beings from another universe or dimension--not one we could see on get to by travelling through space. If God can create billions of suns and planets he can also create billions of universes. A straightforward reading of the Bible shows that the earth was created before the moon and stars, which were created "to give light" and "to mark times and seasons and days and years."

BTW the lyrics I quoted re from the song "U.F.O." by the Christian singer Larry Norman.