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Gramma loreto
2002-Oct-25, 06:23 PM
Yesterday (10/24) I caught just a snippet of Discovery Channel's If We Had No Moon...interesting stuff. One main point I caught was that if we didn't have the benefit of the Moon's tidal lock, our axis tilt would vary up to 90 degrees. While some form of life may have developed in spite of the resulting wild climate swings, I think all bets for intelligent life would've been off.

It airs again tomorrow (10/26) at 2:00 PM (Eastern Time, I assume) and I'll try to catch it in its entirity.

zwi
2002-Oct-25, 06:32 PM
Have you ever thought that if Venus and Mars each had a nice bright Moon we would have been saved the trouble of the Geocentric hypothesis here on Earth?

Zwi

Atko
2002-Oct-25, 07:05 PM
The Moon is far more important even than the sun. The Moon gives us light at night when we need it and the Sun just sits there in the sky shining during the day when we don't. What a waste!
/phpBB/images/smiles/icon_confused.gif

Superstring
2002-Oct-25, 07:43 PM
Yep...without the moon intelligent life as we know it would probably not have evolved on Earth. The same goes with Jupiter, which helps protect us from comets and outer objects that spin inward. It really gets you thinking about what the chances are of intelligent life elsewhere...

g99
2002-Oct-25, 10:21 PM
Ahh and you can't forget the entertainment qualities of pluto!!! /phpBB/images/smiles/icon_smile.gif

Hmmm...If we never had something like our moon those cool nights on the side of a road siting on the roof of your car with your favortie girl/boy friend lyeing next to you staring up at the night sky would seem just that much less magical. (i'm a romantic at heart)

Jetmech0417
2002-Oct-26, 02:19 AM
"Life will find a way." (not-so-obscure reference.) We've found life in so many unusual places on our own planet, there's no doubt in my mind that life has evolved in other places. And, who's to say that bacterium don't think we're the unintelligent ones?

BTW, I've had many a great night lying in the bed of my truck with the one I love staring at the stars on moonless nights.

g99
2002-Oct-26, 03:52 AM
On 2002-10-25 22:19, Jetmech0417 wrote:
"Life will find a way." (not-so-obscure reference.) We've found life in so many unusual places on our own planet, there's no doubt in my mind that life has evolved in other places. And, who's to say that bacterium don't think we're the unintelligent ones?

BTW, I've had many a great night lying in the bed of my truck with the one I love staring at the stars on moonless nights.




Ahh that quote is from my favorite book. Jurassic park by michael chrichton. It probobly was in others, but it is specifically mentioned in the book. I love that book.

Ahh, it is amazing to stare at the sky at night, but with a great girl in your arms, just having the moonlight shine on her face makes it that much more special.

I am anoyed at one thing. There is this great wildlife area near my university that you can pull off of the side of the road and there are no lights to polute the sky for miles. But lately on football game days people have been out there have bbq's and feeding the local wildlife (specifically alligators) and then leaving their trash for them to choke on. It was reported in the papers that they have killed several gators. So now they don't allow anyone to stop there. I hate that some people ruin a perfect viewing spot for others just beacuse they cant be bothered to bring a trash bag. now i really have to search hard to find a good spot. Arrrggg...

Colt
2002-Oct-26, 09:08 AM
As this is my first post, hello!

I agree with the moon being vital to life here on the earth. Even if we did evolve and all, think of how much our history would have changed. Would we have landed on Mars as the first stop? Anyway, hello again.

If any of you go to http://www.trekbbs.com, you can find me lurking about in the Trek Tech forum. /phpBB/images/smiles/icon_smile.gif -Colt

Superstring
2002-Oct-26, 01:11 PM
Welcome to BABB, Colt. Look forward to more of your posts.

g99
2002-Oct-26, 06:35 PM
On 2002-10-26 09:11, Superstring wrote:
Welcome to BABB, Colt. Look forward to more of your posts.



Ditto!!

DStahl
2002-Oct-27, 09:01 AM
As far as life and the genesis thereof goes, we have a terribly small sample size--one. I am a little bit nervous about drawing conclusions about the possibility of life arising on other worlds without a few more data points from which to extrapolate.

It may indeed be that a large moon and a Jovian sibling planet may be necessary for life. It may also be that planetary configurations of which we wot not may be equally suited to the genesis of life. I suspect we would be wise to reserve judgement and be very tentative on our pronouncements as to what is necessary for life until we have a bit more data.

GrapesOfWrath
2002-Oct-27, 10:17 AM
Are you guys familiar with Isaac Asimov's The Triple Triumph of the Moon (http://www.magna.com.au/~prfbrown/i_asimov.html)? He apparently wrote it after watching the Apollo 17 liftoff.

The three "triumphs":
1) The moon made it possible for man to evolve and so exist.
2) The moon made it possible for him to develop mathematics and science.
3) The moon made it possible for him to transcend Earth and conquer space.

Donnie B.
2002-Oct-28, 02:41 AM
Asimov wrote about this issue? What a shock! Considering the paltry amount of material the guy produced... /phpBB/images/smiles/icon_biggrin.gif

Donnie B.
2002-Oct-28, 02:43 AM
On 2002-10-27 04:01, DStahl wrote:
As far as life and the genesis thereof goes, we have a terribly small sample size--one. I am a little bit nervous about drawing conclusions about the possibility of life arising on other worlds without a few more data points from which to extrapolate.
Right, and the conclusion that you'd draw from this one sample is probably quite misleading. As things stand right now, 100% of well-explored planets have life!

Whether there's any intelligent life there is still debatable... /phpBB/images/smiles/icon_smile.gif

nebularain
2002-Oct-28, 04:02 AM
Beam me up, Scotti - there's no intelligent life down here!" /phpBB/images/smiles/icon_biggrin.gif

g99
2002-Oct-28, 06:49 AM
Ahh but there was intelegent life somewhere. But it was killed by the Mars Suveyer when its petals unfolded and killed it. /phpBB/images/smiles/icon_smile.gif

_________________
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<font size=-1>[ This Message was edited by: g99 on 2002-10-28 01:49 ]</font>

Jetmech0417
2002-Oct-28, 09:04 AM
As things stand right now, 100% of well-explored planets have life!

This particular planet isn't all that well explored if you really think about it. There's still sooo many things we don't know. Probably things we'll never know.

Superstring
2002-Oct-28, 11:56 AM
On 2002-10-28 04:04, Jetmech0417 wrote:

This particular planet isn't all that well explored if you really think about it. There's still sooo many things we don't know. Probably things we'll never know.



Ditto....and to me that's what makes astronomy so addictive. /phpBB/images/smiles/icon_wink.gif

Colt
2002-Oct-28, 04:58 PM
I love the question on numerous tests from high school Astronomy classes which goes something like: "How many planets with life, or intelligent life have we found?" It is amazing the range of figures given and which ones are listed. "Vulcan" and "Mars" are a few of the common ones. /phpBB/images/smiles/icon_wink.gif -Colt

aurorae
2002-Oct-28, 05:41 PM
On 2002-10-25 14:23, Gramma loreto wrote:
Yesterday (10/24) I caught just a snippet of Discovery Channel's If We Had No Moon...interesting stuff. One main point I caught was that if we didn't have the benefit of the Moon's tidal lock, our axis tilt would vary up to 90 degrees.

I've heard and read this in various places.

And I have always wondered, if this were true, why the other inner planets (Mercury, Venus, Mars) have axial tilts that are not widely different. None of them have a tilt like Uranus, for example.

If the answer is that the other inner planets have had their tilt change widely over time, my next question would be, what evidence do we have that occured?

For example, what would we expect to find on Mars if Mars had an axial tilt of 90 degrees sometime in the distant past? What would that tilt do? Would it change the climate enough to leave distinct sedimentary deposits?

Without some evidence, then the theory that the planetary tilts change without a large moon is just conjecture.

daver
2002-Oct-28, 08:48 PM
> Without some evidence, then the theory that the planetary tilts change without a large moon is just conjecture. <

My vague recollection is that numerical simulations had the earth's axis swinging up to 60 degrees or so.

You state that neither Venus, Mercury, or Mars show evidence of such shifts. I'm not sure that Mercury counts--it's so close to the sun that the sun ought to function more or less as the moon is supposed to in elminating axial swings. And you might be able to make a case that Venus' axis is already flipped--its tilt is 177 degrees.

I'm not sure what kind of geological evidence would provide evidence of a planet having a higher axial tilt in the past. I think the best argument in favor or against the idea would be more computer simulations.

GrapesOfWrath
2002-Oct-28, 09:23 PM
The tidal effect of the Sun on the Earth is almost the same (well, half) as the tidal effect of the moon. The Sun's effect on Mercury and Venus would be quite a bit greater.

Gramma loreto
2002-Oct-28, 11:24 PM
On 2002-10-28 12:41, aurorae wrote:

And I have always wondered, if this were true, why the other inner planets (Mercury, Venus, Mars) have axial tilts that are not widely different. None of them have a tilt like Uranus, for example.

Just responding off the cuff...

I seem to remember reading that Mars did have a tilt of up to about (maybe) 90 degrees. I'd have to do some additional reading to discover the methodology used to reach that conclusion.

Mercury is tidal locked isn't it? Don't its periods of rotation and revolution roughly match?

daver
2002-Oct-28, 11:55 PM
> Mercury is tidal locked isn't it? Don't its periods of rotation and revolution roughly match? <

Integral ratios--3:2. That's 3 sidereal days in two years, or, if i haven't made a silly mistake, each solar day is 2 years long. So, if you were standing where the sun was directly overhead at perihelion, one mercury year later the sun would be directly underfoot. And in another year directly overhead again. Which, given mercury's eccentric orbit, can lead to some interesting effects (three "noons" per day in some places, or two sunrises/sunsets per day in others).

nebularain
2002-Oct-29, 01:40 AM
On 2002-10-28 04:04, Jetmech0417 wrote:
This particular planet isn't all that well explored if you really think about it. There's still sooo many things we don't know. Probably things we'll never know.

Here's a good example, something called Richat Structure (http://antwrp.gsfc.nasa.gov/apod/ap021028.html) .

GrapesOfWrath
2002-Oct-29, 01:48 AM
Nice use of today's APOD!