Plenty of Earths await discovery

[eek.]

<TABLE cellSpacing=0 cellPadding=0 width=629 border=0><TBODY><TR><TD colSpan=3>My own opinion is that I disagree, and of those that do exist 99% will get hit


by asteroids too often for higher order lifeforms, like frogs/cats/birds to exist.

Apparently Jupiter has saved our earthly asses thousands of times, it hoovers up loads of asteroids and keeps most of the others in an asteroid belt by way of its massive gravity.
70,000 viewable asteroids have been found so far...
http://www.earthsky.com/shows/shows.php?t=20040313

Jupiter is more than twice as big as all the other planets combined.
http://www.nineplanets.org/jupiter.html

...although they do know a bit more about this stuff than me....

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Plenty of Earths await discovery



</TD></TR><TR><TD vAlign=top width=416><!-- S BO --><!-- S IBYL --><TABLE cellSpacing=0 cellPadding=0 width=416 border=0><TBODY><TR><TD vAlign=bottom>By Jonathan Amos


BBC News science reporter, in Birmingham


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The Universe could host billions of Earths





</TD></TR></TBODY></TABLE><!-- E IIMA -->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.



http://news.bbc.co.uk/1/hi/sci/tech/4411865.stm

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[Woody0]

Not only that but Titan which orbits Saturn has methane "snow" and a liquid methane ocean, together with other complex organics, that could perhaps lead to life unlike we know it.

OTOH Europa, which orbits Jupiter, likely has a liquid water ocean beneath its frozen surface, leading to the possibility of life as we know it.

Should we survive, we will reach these moons long before we leave our solar system.

 

[JinnRikki]

Since the only planets we can now detect are the massive ones in distant star systems, I would say large gas giants are the rule in solar systems instead of the exception. Scientists just don't know enough about these systems to say one way or another. I'm hopeful. But I also could be wrong. :>Grin>

 

[Woody0]

If I understand correctly JinnRikki you are saying that maybe gas giants are the rule since only they are detected.

However Earth size planets are currently undetectable. Furthermore I recall that when any kind of planet was undetectable people said that maybe solar sytems were rare. In some ways it falls out of the religious idea that we are special. There is no reason to think this way and it is just as easy to consider that the way things are here is pretty much like everywhere else. This idea in no way negates religous thought, except for the flat earthers who believe the Earth is 6,000 years old.

 

[JinnRikki]

There are other reasons I think gas giants may be prolific. I didn't mean to say there weren't earth size planets. I was agreeing with eek as to gas giants saving our bacon by attracting interplanetary debris. In so doing increasing the chances of other earth like planets. Our own planet has a rich history of meetings with space junk, somehow though, here we are. I think this is probably more likely than not in other systems. I DON"T subscribe to the Rare Earth Theory.

 

[eek.]

There's so much that we don't know about the properties of physical phenomena, mass and energy.

Rogue ocean waves for example have been confirmed as relatively common only recently, and only through physical observation via satellite.

Maths and Physics models claimed they were virtually non-existent.

http://www.rense.com/general31/walls.htm

http://www.seastead.org/localres/misc-articles/ESA_Rogue_Waves_07_21_04.html

 

[WHALE]

Cool !!! :monsters-

 

[Phaedrus]

You space buffs might find this thread of interest.

Another big consideration for a planet being even remotely earth-like is its satellite. Our moon is unique among known satellites wrt to its relatively monstrous size. Without it, we would have no tides, and it is possible that without tidal activity there would never have been any meaningful life in the oceans in the first place.

The only other significant tidal activity in the solar system is around Jupiter, where Big Red's gravitational pull is so strong that it even creates "tides" out of solid rock on Io.

eek has a good point about gas giants deflecting, absorbing or redirecting potential threats to life from smaller inner planets. Most people have no concept of just how large Jupiter is -- to put it in context, if you take away the Sun from the equation, Jupiter accounts for nearly two-thirds of all of the mass in the solar system; i.e. it is very nearly twice as massive as all of the planets, moons, asteroids, comets, Kuiper Belt Objects, etc. Combined.

Cool stuff, and way better than arguing.


Phaedrus

 

[DarrylParsons]

Cool stuff, and way better than arguing.

Dang! When I saw your name after a mini-hiatus I thought there might be some cool new arguments...oh well...don't forget DWD, the relatively new (informed and intelligent) poster with whom you might find some duking left before reaching a stable equilibrium!? Your pay-per-view fans are eagerly standing by...I think XP would gladly offer herself up as the prize in such a bout, the only catch being that she gets to be the judge.

 

[Phaedrus]

OK, well, um, only a typical socialist dipshît would fail to consider the ramifications of our unique-in-known-astronomy satellite. Just as capitalism provides the primary drive for all human prosperity, our moon drives the tides, which are arguably the primary driver of advanced life. Of course, since our moon is unique among satellites, the pimped sheep of the left are opposed to it by default, despising it for the very features which make it a benefit to us all. I'm sure they'd rather it be more like e.g. Phobos and would be willing to sacrifice life in the oceans (and by extension, eventually, human life) just to keep Mars' deformed, limp-dick-looking little satellite from feeling inadequate.

Better?


Phaedrus

 

[eek.]

I agree with the above. Good post.

 

[DarrylParsons]

Better?

It is a bit more provocative, so yes I suppose it's better. But of all the usual suspects Eek would have been the most likely to disagree, and unfortunately that bet just lost, so we'll have to do even better next time I'd say. :think2: