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Extrasolar Planet Could Harbor Life
BlueMorpho writes with a link to a Space.com article about a recently discovered extrasolar planet that may be able to harbor 'life as we know it.' Orbiting around the star Gliese 581 is a small rocky ball that might have the same liquid ocean and drifting continent configuration we're familiar with. The find may be unique in all of space exploration as this planet appears to be within a habitable band of temperatures for life, and is categorically not a gas giant. "The bottom line is exciting ...The conditions for life could be there, but is life itself? As yet, there's no way to know unless the planet has spawned beings that are at least as clever as we are. As part of the SETI Institute's Project Phoenix, we twice aimed large antennas in the direction of Gliese 581, hoping to pick up a signal that would bespeak technology ... Neither search turned up a signal."
hey kids! Exciting news a planet could have life - assuming it has an atmosphere. And if it does have that atmosphere, it doesn't overheat the planet through greenhouse heating. And oh yeah, all we know about it is its orbit and mass. And it almost definitely doesn't have life. Aren't you excited?
When the media flogs "science" stories like this, full of marginal ideas that probably aren't true are we just conditioning the public to ignore actual science as pie in the sky crap? Or does the break from Paris Hilton news stories have some tangible benefit to educating society at large?
The planet is so close to the star that it's likely tidally locked so that only one side faces the sun and the other side is in eternal night. The temperature differential between the hot day side and the cold night side might cause the border to be under constant storm activity.
A "year" where the planet rotates around the star is only 13 days. If tidally locked, a "day" is the same amount of time.
The same tidal forces would also make any large oceans on the surface prone to immense tides. The strong tides may also result in more tectonic activity than on Earth.
I think you need to recheck some of your facts.
Our solar system moves in and out of the spiral arms as well as up and down through the galactic plane. We go through the galactic plane about every 35 million years, and through the spiral arms about every 100 million years. Some postulate that these timescales coincide with various mass extinctions that occurred.
The axial tilt of the Earth changes all the time. The tilt angle varies between 22 and 25 degrees over a period of about 41000 years. There is also precession of the orbit that happens on a 22000 year timescale. The changing tilt angle changes the severity of the seasons (length of seasons, ice ages, etc.), but it doesn't have anything to say about whether the planet could harbor life.
There isn't anything magical about our molten core and magnetosphere. We usually expect large rocky planets to have them, so we find it unusual if a planet doesn't have a magnetosphere.
I wouldn't say that the asteroid belt has protected us. The asteroid belt is basically a planet that either didn't form, or didn't survive. Its existence is probably one of the biggest threats to our survival on this planet. It is a race to see whether a large asteroid or comet hits our planet and wipes us out. Nobody doubts that it will happen again in the future; we just don't know when it will.
The Moon actually causes a drag on the planet that is slowing down the Earth rotation. I don't recall hearing what an ideal rotation rate for the Earth is to sustain life.
Once one gets their head around how many stars there are in just our own galaxy, many people consider it a given that there is life all around in the galaxy. Even if you take the most pessimistic odds for life to develop, once you multiply that by the number of stars out there it would seem to be very likely. The most famous statement of this is the Drake Equation. Of course, once you consider the extremely large distances between any two stars it is easy to come to the conclusion that all this life will not come in contact with each other (the intelligent life, that is).