For other space news go to: http://www.spacetoday.net
Posted on 09/07/2009 4:54:04 PM PDT by KevinDavis
THE discovery of extrasolar super-Earths - rocky planets about five to ten times the mass of Earth - has raised hopes that some may harbour life. Perhaps it's a vain hope though, since it now seems that Earth is just the right size to sustain lif
(Excerpt) Read more at newscientist.com ...
Yippee! For all of my planet-hopping, I’m glad I settled on THIS one. *SNORT*
I don’t know if the size of the world makes a difference.
"Life as we know it" would be a more appropriate way of framing this article.
Just right for human life anyway.
Except if they're too close for comfort, like Venus.
It’ll make a huge difference. Too much or too little gravity changes a lot of things, including impeding the basic functions of life, but it also influences atmosphere and planetary structural makeup.
I've always rejected this statement or any other like it.
It has always struck me as the quintessential example of circular reasoning.
That Science is making it makes it doubly painful to hear.
Life seems to be is very choosy.. Whatever life is.. Nobody seems to know what life really is.. Dead DNA looks exactly the same as living DNA..
I wonder if a carrot is alive.. When would a carrot be called dead?..
All right by me. I definitely wasn’t thinking of moving to a super-giant gasball. Maybe a moon =O)
bttt
Grinspoon, in the last paragraph would agree with you.
Earth life may be very different from what me might find somewhere else. Something as minor as the wrong wavelengths of light from another sun might make a planet inhabitable to humans.
The earth is sufficiently remarkable that it may be unique in our galaxy.
This is due to the big splat that created the moon which has no iron core but is amazingly similar to earth’s crust.
The earth compared to mars and venus has a really thin crust and a very big core. I suspect that the big collision spit up a lot of the crust to form the moon.
So our planet may be unique to have a big magnetic field, a thin crust, plate techtonics and a really big moon which causes tides, and probably adds tidal heating in the core.
And then you have to have a lot of water to stabilize the atmosphere and temp, but not so much that there are no hard surfaces. I think it would be really hard to create life from nothing in the ocean as there would be too much dilution, but trillions of tide pools are perfect little chemistry labs where life could start.
Bottomline: I think you need the big splat to get an earth and then you need just the right amount of water and that will be a very hard combination to achieve.
“I don’t know if the size of the world makes a difference.”
A larger planet will have a larger gravitational force and require any living thing to be stronger. If the planet has an atmosphere similar to our Earth the air pressure would be much higher and would change the temperature at which water boils. If Earth’s atmospheric pressure were 50 pounds per sq inch, water would not boil until it was heated to 281 deg F. This high boiling point of water and the high gravity would mean that any intelligent life would certainly be very different if not impossible.
All the planets in the solar system are case studies.
Mercury is too close, and is almost a solid iron ball with a tiny almost paper thin crust.
Venus is too close, and has an atmosphere 92 times the density, etc etc
Gravity changes some basic things: a creature’s Mass goes by size cubed (volume) but heat dissipation goes by size squared (area) for example. Thus, a large animal has more thermostat problems, and that is a real consideration for metabolism, given the basic laws of chemistry. It also bears on motor activities of the creature. It changes atmospheric density (thus atmosphere composition). No doubt that life, possibly even similar to that we know, is possible, but it would be dramatically influenced by a large planet (or a small one).
That’s what the scientists get the big bucks for! Next studies will will find that beaches are often close to water.
They from what I can understand that all life is carbon based. From what little I remember of my bio. classes silicon can & does act the way carbon does & that life could form from silicon. In that case what we know gets tossed out the window.
Disclaimer: Opinions posted on Free Republic are those of the individual posters and do not necessarily represent the opinion of Free Republic or its management. All materials posted herein are protected by copyright law and the exemption for fair use of copyrighted works.