Odds against Earth-like planets

http://news.bbc.co.uk/2/hi/science/nature/2701977.stm ^ | January 28, 2003 | Dr David Whitehouse

[HighWheeler]

so far, all the life forms we have found still require water to thrive. Sure, they can aestivate for a while in a dry condition, like a virus, but still need waterborne environment or host to propagate and develop. Water is the key to life.

[HighWheeler]

The tide question is a good one, but I don't think tides would affect the ability for life to develop.

It is interesting that the energy balance of the moon is putting it further from the Earth every year. It is moving away from us about 1 inch per century, and dragging energy from the Earth every month. The result is that the Earth rotational speed is slowing down about (I think) .15 seconds per century. A few hundred million years ago, an Earth day was only 22 hours long.

It is a complex energy transfer, but there are a couple of sites that describe it fairly well.

[BushCountry]

50-100 organisms survived launch, space vacuum, 3 years of radiation exposure, deep-freeze at an average temperature of only 20 degrees above absolute zero, and no nutrient, water or energy source.

I got a feeling that life survives under conditions and places we would never imagine. We just haven't had the opportunity to discover it yet. We need to leave this little rock we live on and I suspect there will be plenty of surprises.

[HighWheeler]

"...no nutrient, water or energy source"

When I was a kid, I raised some "Sea Monkeys" that arrived in that condition in the mail. But they still needed water to thrive. Yeah, I was about 9 or 10 and thought they would be real monkeys. Worst money I ever spent.

[KevinDavis]

This article is BS, there are unkown amount of stars and to say that Earth is the only one live planet in the known galaxy, is pure and simple BS. God created the universe. He also created many planets.

[CharacterCounts]

This article is BS, there are unkown amount of stars and to say that Earth is the only one live planet in the known galaxy, is pure and simple BS.

Where did the article say that?

[RightWhale]

Yes, the moon is leaving the earth. In a sense it has already left, being in an independent orbit around the sun, but at the same time being resonantly locked with the earth for the time being. The tidal pool hypothesis--a condition that might enhance life-forming conditions--seems like an interesting idea, but probably not a necessary condition.

[Mr. K]

yes but from that point on, add a little mass or adjustment in speed, and you have a different orbit, right?

I mean the calculation for orbit does not have a 'well' around the path of a stable orbit where a little bit here or there wouldn't matter because you would wobble back into a stable orbit... Or am I missing something?

[anobjectivist]

Yes, the moon is leaving the earth. In a sense it has already left, being in an independent orbit around the sun Um..the moon orbits the earth, it is not in an independent orbit of the sun and it is not "resonantly locked." Examples of resonance are the four largest moons of jupiter, Callisto, Galileo, Europa, and Ganymede. The tidal pool hypothesis is just that. There are more ideas to life creation but until we are able to recreate it all or at least discover the mechanism for genesis. For all we know life could have arrived from a planetesimal striking the earth that was created in the vaccuum of space.

[RightWhale]

The moon has already escaped from earth. It isn't coming back.

[anobjectivist]

The moon and earth orbit each other around a center of mass that is slightly below the earth's surface to my knowledge. The moon is a separate entity than the earth, but technically orbits the earth. I don't know what you're getting at.

[oldtimer]

I heard, maybe on Paul Harvey that Astronomers are the highest profession with a belief in God - like 85%.

I see some brilliant people replying on this post, and all of this is beyond my comprehension.

But it is small potatoes to what God has given to us through his love, and his son Jesus Christ.

[PatrickHenry]

Sorry about a few duplicate pings from Junior and now me.

[This ping list for the evolution -- not creationism -- side of evolution threads, and sometimes for other science topics. To be added (or dropped), let me know via freepmail.]

[RightWhale]

There are two other moons of earth. One is Cruithne, and there is the asteroid discovered last year, I don't know if it has an informal name. The other two are also resonantly locked with earth, but their apparent orbits as seen from the earth's perspective are far from elliptical at this time--horseshoe-shaped. Nevertheless the moon, Luna, is gradually changing its orbit from elliptical to horseshoe. Whether it eventually becomes a true Trojan point orbit is unlikely since other planets, mainly Jupiter, exert a strong influence. The moon has escaped, but it is taking its own sweet time leaving the 'hood.

[HighWheeler]

"it is not "resonantly locked."

Sure is, "Right"Whale is right. The rotation time and the orbit time around the Earth are the same, so we see the same face all the time. The slight wobble is due to the eccentricity of the orbit.

[HighWheeler]

Luna is constantly leaching energy from each rotation around the Earth, and is adding distance from us every day. There will be day in the far, far future that Luna finally escapes the Earth's gravity and ventures off on its own. It will be a tiny light by the time that happens.

BTW, do you know that the Earth has a second moon? It's called Cruithne, and it has an incredible complex orbit.

[HighWheeler]

well I should have read further before posting.

[Centurion2000]

I think the best analogy I've heard is that it is like trying to detect a speck of dust orbiting a 100 watt light buld from 100 meters away.

It's a lot worse than that. If stars were basketballs you could put one on the White House lawn to represent the sun. Earth would be across the street and literally be a dust grain.
Alpha Centauri (second closest star to Earth at 4.36LY) would be in Red Square if the model were to scale.

[HighWheeler]

I do a presentation to schools on the Solar system. I use a standard 12 inch globe to represent the Sun, and pass out a BB to every kid in the class. They stand 107 feet away to represent the average distance of orbit between the two. The scale of the BB is almost perfect.

It is a big hit with the teachers and the kids.

[Bloody Sam Roberts]

They stand 107 feet away to represent the average distance of orbit between the two.

You have a BIG classroom, neh?