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.

[El Gato]

I have to wonder why He decided to place our planet inside a cosmic shooting gallery.

Because adversity builds character?

[The KG9 Kid]

"... Because adversity builds character?"

Explain Palestinians then.

[mr.sarcastic]

mr.sarcastic: This is about as scientifically significant as my estimation that there are 30 billion ants in my backyard.

My back yard: At least. 8^)

LOL! When "my back yard" starts talking back to me, I know it's time to up the meds... :-)

[capitan_refugio]

I look at it this way:

There might be 30 billion earth-like planets out there ...
and we got stuck with BOTH Bill and Hillary!
What are the odds!?

[capitan_refugio]

I look at it this way:

There might be 30 billion earth-like planets out there ...
and we got stuck with BOTH Bill and Hillary!
What are the odds!?

[capitan_refugio]

Sorry about the double click and resultant double post! ;^(

[Ahban]

This is the safest neighborhood in the universe Kid. One supernova within 300 light years and only cockroaches and below survive. If we pass through a nebula, the gas slows down the Kuiper belt and OOrt clould objects and WE WOULD BE a shooting gallery. We have either been VERY VERY VERY VERY VERY lucky, or it was fate.

My guess as to why we are occasionally in a cosmic shooting gallery is that occasionally there are some of us that need to be shot.

[aruanan]

That's not the way probabilities work. Once a particular case has occurred, it has no influence on future outcomes. You can test this yourself very simply if you like. The probability of getting a tail when flipping a coin is 1 in 2. Thus, the probability of getting two tails in a row, is, as you rightly say, the square of the probability of getting one tail, i.e., 1 in 4. According to what you're saying, in a series of flips, the occurrence of a tail, should reduce the probability of getting another tail on the following flip. But this is not so, try it and you will find that a tail will follow a tail in a sequence 1 out of 2 times.

What I wrote is indeed the way probabilities are calculated. You're making a simple error. You're taking a string of outcomes and then saying that since the next successive outcome has a 1 in 2 chance of occurring the next successive outcome has a 1 in 2 chance of occurring. That's merely a tautology. That has nothing to do with what the probabilities are, or were, for a particular set of outcomes to occur through using a 1 in 2 mechanism. Although the probability of your flipping a tail remains 1 in 2 at each successive roll, the probability of your flipping a tail 8 times in a row is 1 in 2X2X2X2X2X2X2X2 or 1 in 256.

Using another tool of chance favored by the house because it wins if you do not get a particular arrangment, although there is one chance in six that you will throw a six with a die on any particular roll--since there is but 1 face out of 6 that has the six--and no roll has anything to do with any other roll, that you will throw a second six on the second roll, there is one chance in thirty-six, not one chance in six. We're no longer talking about the probability of 1 isolated incident to occur but the probability of a particular arrangement of isolated incidents to occur. The probability of your throwing any particular number is 1 in 6. The probability of your throwing numbers 1 through 6 consecutively is no longer 1 in 6, but 1 in 6 X 6 X 6 X 6 X 6 X 6 or 1 in 46,656.

In another dicey situation, let's say your chance of randomly meeting a total stranger

1. with the same three initials as you is 1 in 17,576,
2. whose mother has the same name as your mother is 1 in 23,000
3. with the same eye color is 1 in 5,
4. with the same birthday is 1 in 365.25.

The probability of all four of these conditions occuring simultaneously isn't the sum or the difference of the probabilities, but the product: 1 in 17,576 X 23,000 X 5 X 365.25 or 1 in 738,257,910,000.

[Grig]

"It is logically possible to believe both (or is it all three). God could very well have created everything by using evolution"

I don't see that as possible, there was no death before the fall, so how could there be generation of evolution taking place? Also, the plants and animals were created to bring forth their OWN kind, not a different kind as evolution requires.

[Vinomori]

Does this mean that there are 30 billion deities?

[Grig]

There is actually an old Sci-Fi movie with that premise. An astronaught goes up on some mission, something goes wrong, and he winds up on a mirror-earth on the other side of the sun (and his mirror-self winds up on our earth the same way)

Actually, if I remember correctly, it's possible to have 3 life supporting planets, each in their own orbit around the same sun. If mars were heavier (so it could hold onto a denser atmosphere) then it would be warm enough for liquid surface water.

[RadioAstronomer]

Ping :-)

[RightWhale]

And your reasong for thinking so???

I noticed that the assertion that there are 30 billion possible earths was unsupported by either model or data. So I simply asserted something equally unsupported.

[Vast Buffalo Wing Conspiracy]

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.

Rubbish. Given the sheer numbers of stars and planets in the universe, some of these planets are going to be the same size as earth, located the same distance from a star similar to our sun. We don't know how many planets will meet those criteria, but those that do will indeed be earth-like, by definition. The circumstances that created the Earth are not that extreme or unusual.

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?

He's doing pretty well, actually. Last I heard, he was still King of Spain, whereas you and I are not.

Seriously, Spain did very well out of its New World explorations, even though the actual rewards were somewhat different from what Columbus was expecting - better, actually.

Earth-like planets most certainly do exist; the only question is how many are there, and how far away. One thing we can predict though: even if there are 30 billion earths, there isn't intelligent life on any of them, if Earth is any example to go by!

[Vast Buffalo Wing Conspiracy]

Can you imagine the fallout in society and the scientific community if we get to another such world and find the same plants and animals and humans as are here? And what if they have a religion that matches one here as well? I think the mother of all cover-ups would take place.

No, I think our religious types and their religious types would immediately start fighting over who had the "one true religion".

Science will simply deal with the evidence as it is discovered. The odds are much better, going on past experiences, that many different and new things will be discovered on other planets, all of them following natural laws, but none of them exactly repeating what we have here on earth.

But in spite of these facts, we will still have fundamentalist types trying to explain these facts away. Not having to answer to the scientific method, the fundamentalists will always be free to use any line of sophistry to avoid reality.

[RightWhale]

Earth-like planets most certainly do exist

One does. One. Singular earth. No others are known, and saying there must be others is as wild a speculation as saying there is just one --this one.

[Vast Buffalo Wing Conspiracy]

"It is logically possible to believe both (or is it all three). God could very well have created everything by using evolution"

I don't see that as possible, there was no death before the fall, so how could there be generation of evolution taking place? Also, the plants and animals were created to bring forth their OWN kind, not a different kind as evolution requires.

That's because you are a fundamentalist and a literalist; you are incapable of thinking "outside the box" which is why the Genesis stories are written in a nice, simple fashion so that you can understand them.

Who says that "the Fall" occured inside Time? If one is outside Time, then by definition there can be no death, since death is a product of Time - that is to say, of change and evolution. Mankind Falls, and is therefore in Time, and therefore can die, can change, can evolve.

Likewise for the rest of creation. And since evolution also recognizes that animals also bring forth their own kind, there is no contradiction there, either. But change builds up over time, so there is evolution. Just as there is similar change and evolution in language, culture, politics, the environment, the weather, tectonic plates, and the entire universe itself.

Your problem is that you are a literalist, who wants to deny the reality of change. There's no hope for you, I'm afraid, unless you are willing to give up this mental crutch. It's not atheism you are fighting against; it's anti-literalism.

We are incapable of understanding what God is like, but I'm pretty sure he is not a big buy with a white beard, up in the clouds, who rains down thunderbolts and creates Mankind from the clay with his bare hands. I think something like God, which is beyond Time and Space, is a little bit more sophisticated than that.

[shirleyvalentine]

Without that big moon no planet will be an earth.

[Vast Buffalo Wing Conspiracy]

One does. One. Singular earth. No others are known, and saying there must be others is as wild a speculation as saying there is just one --this one.

If I go outside at night with my eyes closed and I feel and hear something wet falling on me that sounds like rain, which is more likely - that it is raining, or that a flock of bats happens to be flying over me and taking a group piss? Rationality sides with the probable, not the merely theoretically possible.

Saying that this is the only Earth we are aware of is one thing; saying that this is the only Earth-like planet in the universe is straining probablity far, far beyond what is rational; and saying that we cannot rationally speculate about the probability of other earths is itself, irrational.

The probability that there are other Earth-like planets in the universe, based on what we know so far, is extremely high; the only question is how many of them there are, and where they are. It is irrational to call this rational speculation "wild speculation"; you are taking skepticism far beyond its rational limits, and trying to insist we cannot speculate rationally based on existing evidence. You are wrong; we can.

If you insisted that this was the only Earth-like planet, you would be the one engaged in "wild speculation". If this were true, the universe would be weirder then we thought, and most of our existing scientific theories and the evidence these are built on would have to be thrown out. Smart money is on my side (one or more other earth-like planets in the universe, besides Earth); the only question is when we will discover them, and where, and in what quantity.