Plenty of Earths await discovery

BBC ^ | 4/5/05 | Jonathan Amos

[LibWhacker]

The Universe could host billions of Earths

British researchers are more confident than ever that there are "Earths" out there waiting to be discovered.

The scientists say perhaps a half of all the known planetary systems today could be harbouring habitable worlds.

It must be said most of these systems are strange places where supergiant planets orbit close in to their stars.

But Barrie Jones and colleagues say their modelling work suggests that even with this oddness, there should be room for small rocky planets.

The Open University team presented its ideas here at the UK National Astronomy Meeting on Tuesday.

They extend recent and previously published theoretical work, "putting it on a firmer modelling basis," Professor Jones told the BBC News website.

The research calculates the likely number of Earths out there, based on what we know about how planets form and the conditions needed for life - in particular, the requirement to sit in the part of a solar system that is neither too hot for liquid water, nor too cold.

'Disaster' area

"The conclusions haven't changed, I'm pleased to say. Roughly half the systems out there could have Earths in their habitable zones today and have been there long enough for life to develop," Jones added.

The limitations of current telescope technology make it extremely difficult to view so-called extrasolar planets directly.

Astronomers have therefore made most of their detections indirectly - by finding stars that appear to "wobble" under the gravitational tug of what must be nearby, very large planets.

The technique has the bias of only showing up apparently bizarre systems - where planets that are sometimes many times the mass of our own Jupiter circle their stars in orbits that are smaller than Mercury's.

And this presents a problem because current thinking holds that these huge Jupiters probably formed some way out from their stars before migrating inwards. And if they did that, the chances are they would have destroyed all in their path, including any fledging Earths.

"We've now got some simple rules for establishing how far these disaster zones extend," explained Professor Jones.

Moving zones

Encouragingly, his team finds there is plenty room and time for Earths to evolve.

"At the stage these great giants sweep through, the Earths are not formed - they are still smallish planetary embryos. They get scattered but the simulations show enough material remains that Earths can form after the migration of the great giants has taken place."

The team found about half of the known exoplanetary systems offer a safe haven for a period extending from the present into the past that is at least long enough for life to have developed on any such planets.

The situation is complicated slightly by the fact that the habitable zone migrates outwards as the star ages, and in some cases this changes the potential for life to evolve.

Thus, in some cases a safe haven might have been available only in the past, while in other cases it might exist only in the future.

These scenarios of past extinction and future birth increase to about two-thirds the proportion of the known exoplanetary systems that are potentially habitable at some time during the main-sequence lifetime of their central star.

The research by Barrie Jones, Nick Sleep, and David Underwood has been published in Astrophysical Journal.

[AntiGuv]

BTW, I read the original Profiles of The Future when I was very young, and that's what kindled my fascination with science and technology - in particular futurism. I highly recommend the millennium edition!

Profiles of the Future: An Inquiry Into the Limits of the Possible

[boris]

"Or maybe we are alone (though I believe this is unlikely)."

Read this and you will change your belief.

--Boris

[AntiGuv]

If there were only an average of 1 civilized earth per every 10 galaxies there would still be at least 10 billion civilizations out there....

[AntiGuv]

Or, to underscore the likelihood of other earths even more - "rare earth" hypotheses notwithstanding - if there were only 1 planet with sentient beings for every trillion star systems - that's every 1,000,000,000,000 stars - there would still be at least 10 billion civilizations out there.

[hosepipe]

[ The Universe could host billions of Earths ]

1) or NONE...
2) or very few...
3) or some other habitable planet unlike earth..
4) or some other options..

Just because something could be, does not mean it is..
There could be NO war, everybody could love each other.. and poverty could be a thing of the past.. The odds of these things happening is not great either.. Even all/most liberals could wake up some morning and say, Damn, I was WRONG..

I like Carl Sagans bromide, "Life had to happen somewhere FIRST, its possible earth could be that planet".. Ol' Carl was at least was logical to a fault.. Occams razor is very sharp..

[AntiGuv]

The odds of these things happening [here soon] is not great either..

The odds of those things you mention happening on earth soon are not great; however, the odds of the universe hosting billions of rocky planets in the liquid water zone appear extraordinarily high.

[AntiGuv]

PS. The odds of the universe hosting some other habitable planet unlike earth are 200%+. There are at least two of them in our own solar system.. ;^)

[Drammach]

Or as Captain Picard observed, "Any tecnology sufficiently advanced beyond our own would be indistinguishable from magic."

PICKARD??? PICKARD???
Bite your tongue.. hard...)
And never do that again...

It was Arthur C. Clark

[TBP]

when they have aborted themselves to death

If "environmentalism" doesn't get them first.

[Koblenz]

Or as Captain Picard observed, "Any tecnology sufficiently advanced beyond our own would be indistinguishable from magic."

I think someone else said that first?

[muir_redwoods]

Humans are a lot more than just an excellent brain. We possess the finest construct found anywhere in nature. There's one at the end of each arm. The hand has made all of our technology possible. The dolphin could be three times smarter than we are and never achieve more than it already has. It can't use fire, metals or electronics. It can't manipulate stones so as to create a sharp edged tool and couldn't use one if it could produce one.

Then there are the imponderables. Maybe we are a rare species not bothered by radio waves. Maybe other intelligent species find it carcinogenic or simply obnoxious to be around. Maybe we possess more curiousity than most and the vast majority of intelligent species simply don't care.

There are probably a million reasons why we are not yet in contact with other species first among them is we simply may not be paying attention to what they think is an obvious message. Frustrating isn't it?

[boris]

"If there were only an average of 1 civilized earth per every 10 galaxies there would still be at least 10 billion civilizations out there...."

If there are less than 10 civilizations in this galaxy then we are effectively alone. Galactic travel? Get serious. Galactic communication? Come now.

--Boris

[KevinDavis]

My take on this is that we are not the only planet that can support life. After seeing the pictures from the Hubble, there is no way we can be alone.

I rember seeing something on the Science Channel is that Gas Giants serve to purpose. One purpose is to protect the earth like planets from disasters like the Comet Hale Bopp or it could be bad when the Gas giants crash into an Earth like planet.

[KevinDavis]

No keep the liberals here..

[Squawk 8888]

So I found out but in my defence, I never read that particular Clarke book and the line WAS used in a Star Wreck episode.

[Larry Lucido]

I wonder if all our extra socks will be there.

[Truth29]

If you haven't already, you need to see Stargate Atlantis. Te Wraith fit your fears perfectly.

[anymouse]

Not necessarily worthless, but of relatively low value to us given our lack of transport capable of getting us there in a practical time frame. The same was once said of California.

Should we find a truly Earth like planet within a few light years away, it might just spark a technology race to develop high fractional light speed space propulsion and other necessary technologies that would make the trip feasible.

But just as likely such technologies might make it more practical to develop closer space resources into habitable alternatives to Earth.

Either way, those of us stuck back here on Earth will benefit from those technological breakthroughs. Assuming that we don't let NASA squander their precious research funds on operating white elephant projects like they have over the last 20 years.

[RightWhale]

You are toying with us. We have the ability to get to the moon in three days and still don't have any kind of settlement or commerce with the moon. Another star system?

[stremba]

I forget where I heard this, but this is the explanation for lack of contact that I like best: (although it does rely on human nature, which may not apply to an alien species). If we simply scan the sky for a radio message from an alien civilization, if there is one, we will know immediately, or at least in the amount of time it will take for us to recognize the alien signal as such. If we broadcast a message on the other hand, we must wait for the message to get to its target civilization and then wait for a reply. It's possible that we wouldn't know for several hundred years or more if we were successful. Humans naturally would rather do the former and just listen rather than broadcasting and leaving the question open until our descendants hear an answer. However, what if other species think the same way? It's possible that no other species is broadcasting for the same reason that we choose to just listen.