the age of the moon ( recent news )

[unlearningthemistakes]

<br /><i><b>MUENSTER, Germany (dpa) ---scientist have announced the discover of the precise age of the moon, give or take 10 million years—it is 4,57 million years old and shows little sign of ageing.</b><br /><br />The date of formation, published Friday in the US journal Science, was about 30 million to 50 million years after the solar system, scientist from the universities of Muenster and Cologne in Germany and Oxford in England said.<br /><br />The date fits in with the contemporary theory of the moons origin: that an object the size of Mars collided with an earlier planet dubbed “ProtoEarth”, leaving a disc of waste matter in orbit that finally clumped together as the moon.<br /><br />The study suggest the moon initially had a surface of molten magma which cooled in a relatively quick 20 million years.<br />Moon rock has been changeless since, whereas earth rock has been repeatedly melted and reformed.<br />The oldest know rocks on earth are 500 million years younger than the planet itself, the University of Muenster said.<br />The moon’s birth date was derived from many fragments of rock brought back by the US Apollo landings on the moon. Past estimates could only date the moon to the first 100 million years of the solar system.<br />Led by University of Muenster scientist Thorsten Klein, the team checked how much of the substance wolfram 182 was in moon rock.<br />It is partly a product of radioactive Hafnium 182, so its presence can be used as a clock.</i><br /> <div class="Discussion_UserSignature"> <p>pain is inevitable</p><p>suffering is optional </p> </div>

 

[bonzelite]

so what mars-sized object is it? the story of the collision with earth is more interesting to me than the moon.

 

[unlearningthemistakes]

it is a theory about moon's origin. Giant Impact Model.<br /><br />This model envisions a glancing impact of a Mars-sized body into the young Earth. The tremendous impact spews some of the Earth's mass ( and a large fraction of the impacting body's mass) into orbit around Earth. The metal-rich core of the impacting body joins up with the Earth; what was it's rocky mantle remains in orbit. The moon accreted from this material.<br /><br />Overall, the Giant Impact Model has the fewest serious problems and seemed so far to be the best bet for a reasonable explantion of the moon's origin.<br /><br />(against Binary Accretion model and The Capture model) <div class="Discussion_UserSignature"> <p>pain is inevitable</p><p>suffering is optional </p> </div>

 

[bonzelite]

so where is the mars-sized object now? <br /><br />i'm not dissing the theory. just curious.

 

[unlearningthemistakes]

<font color="yellow">The metal-rich core of the impacting body(<---the mars-sized object) joins up with the Earth; what was it's rocky mantle remains in orbit. The moon accreted from this material. </font> <img src="/images/icons/smile.gif" /><br /> <div class="Discussion_UserSignature"> <p>pain is inevitable</p><p>suffering is optional </p> </div>

 

[bonzelite]

oh. sorry. cannot read tonight. <br /><br />so the earth was initially smaller, then? <br /><br /><br />

 

[unlearningthemistakes]

<i>perhaps</i> <img src="/images/icons/smile.gif" /> <div class="Discussion_UserSignature"> <p>pain is inevitable</p><p>suffering is optional </p> </div>

 

[bonzelite]

so this leads me to think about how and when did earth's oceans get here? if a planet collided with the earth with oceans from it's very beginning, it would seem that the earth's water would have been lost either to space, vaporized, or sent intermingling with the interior(s) of the planet(s). <br /><br />

 

[rfoshaug]

If the water vaporized, it wouldn't be lost - just suspended in the atmosphere for some millions of years before raining back down when the planet cooled.<br /><br />But I think I have read that there wasn't much water on Earth at that time. The water came later through millions of years of comet impacts (comets are water rich and comet impacts were much more frequent at that time).<br /><br />Not sure though. <div class="Discussion_UserSignature"> <p><font color="#ff9900">----------------------------------</font></p><p><font color="#ff9900">My minds have many opinions</font></p> </div>

 

[mlorrey]

Yes, both bodies likely had early anoxic atmospheres similar to Venus. Venus currently has 92 earth-atmospheres worth of gases. The early post-impact Earth had about 52 times its current atmosphere, most of which, when comets added water and life first arose, became translated over time into coral, then compacted into limestone, as well as methane hydrates in the ocean bottoms, to become oil deposits through subduction and hydrogenation.<br /><br />

 

[unlearningthemistakes]

Im not fond of geology. <img src="/images/icons/tongue.gif" /> <div class="Discussion_UserSignature"> <p>pain is inevitable</p><p>suffering is optional </p> </div>

 

[mlorrey]

Ah, but geology is fondu of you....

 

[unlearningthemistakes]

<img src="/images/icons/crazy.gif" /><br /><br />I know very little about it. <div class="Discussion_UserSignature"> <p>pain is inevitable</p><p>suffering is optional </p> </div>

 

[CalliArcale]

<blockquote><font class="small">In reply to:</font><hr /><p>so this leads me to think about how and when did earth's oceans get here?<p><hr /></p></p></blockquote><br /><br />That's one of the hottest questions in solar system cosmology right now. Some have speculated that comets delivered the water, but it would mean a much higher rate of impacts than we're having now, and there's not much to support it. It's plausible, but there's really not a good way to test it at present. Nevertheless, it's one of the more concrete ideas, so it's popular.<br /><br />Some asteroid studies have been suggesting that there may be a lot more water in the inner solar system than was previously believed, so it's possible that early Earth was wetter than we all thought. This goes against quite a lot of other models, so there's reluctance to accept that. It's a difficult but very intriguing question. <div class="Discussion_UserSignature"> <p> </p><p><font color="#666699"><em>"People assume that time is a strict progression of cause to effect, but actually from a non-linear, non-subjective viewpoint it's more like a big ball of wibbly wobbly . . . timey wimey . . . stuff."</em>  -- The Tenth Doctor, "Blink"</font></p> </div>

 

[najab]

><i>... it would mean a much higher rate of impacts than we're having now, and there's not much to support it.</i><p>Uhm...the rate of cometary impacts slowed because most of the comets that intercept the Earth's orbit have already impacted?</p>

 

[CalliArcale]

That's how the theory runs. It fits in with the popularly accepted model that there was a period of bombardment early in the solar system's history. I tend to favor it, actually; I was just pointing out that it's difficult to test at present, and that there is still room for other ideas. <div class="Discussion_UserSignature"> <p> </p><p><font color="#666699"><em>"People assume that time is a strict progression of cause to effect, but actually from a non-linear, non-subjective viewpoint it's more like a big ball of wibbly wobbly . . . timey wimey . . . stuff."</em>  -- The Tenth Doctor, "Blink"</font></p> </div>

 

[jatslo]

I favor microbes; the ones that consume minerals, and excrete water.

 

[mlorrey]

<blockquote><font class="small">In reply to:</font><hr /><p><br />That's one of the hottest questions in solar system cosmology right now. Some have speculated that comets delivered the water, but it would mean a much higher rate of impacts than we're having now, and there's not much to support it.<br /><p><hr /></p></p></blockquote><br /><br />On the contrary, the impact rate record on the moon supports it superbly. There was in fact a much higher rate of comet impact. Mullers work with lunar material confirms this.<br /><br />However, there is no reason to expect it all to have come from comets. The early planetesimals would have formed from clouds of all sorts of things, it would have been a long time before the planetary disk were cleaned out enough for the sun to boil off any exposed water in space, long enough for much to fall to the protoplanets. One should note that every planet but Mercury has an atmosphere. There is a threshold gravity that overrides the solar flux tendency to push water out to the colder parts of the solar system. Reduce your albedo with dust and you're just one more inner system comet.

 

[unlearningthemistakes]

http://www.abc.net.au/science/news/space/SpaceRepublish_1531577.htm <br /><br />Im late. sorry. <div class="Discussion_UserSignature"> <p>pain is inevitable</p><p>suffering is optional </p> </div>

 

[bonzelite]

but for round-one of cometary exploration there is no such water to be found. comets are not ice worlds, apparently, but akin to lifeless talcum powdery asteroids. even if they were icy, i find it HIGHLY UNBELIEVABLE that comets alone, impacting, would then generate enough water to create oceans. that is a gigantic "tall tale." like a fish story gone awry. <br /><br />i don't really see how pre-existing oceans when impacted by a rouge planet would then "float for millions of years" and then rain down. i don't see it. i see instead this water being vaporized and violently and ejected into space and lost --as other atmospheres of other planets are believed to have suffered the same fate, with differing atmospheric traits and cataclysms --yet are all attributed to be lost to space-- not retained. <br /><br />so this marks another notch in the totem pole of basic unknowns about seemingly boring or taken-for-granted things: we have really no idea how our oceans got here. and then survived the so-called moon-creation event.<br /><br />if we talk of the moon's age, we must confront our earth's oceans age and the manner in which a liquid surface could have survived global cataclysm of unprecedented scale. in my opinion, a molten earth and mars colliding would have vaporized anything existing on either world, as the velocity of impact between the planets would have been tens of thousands of miles per hour. <br />---------<br />the above article: if the moon is really over 4.5BY old, that puts it on par with the age of the earth, perhaps, lessening the chances of it being younger than the earth. as i read, i felt then the earth/moon system is pretty much the same age. this makes me have less faith in an impact with mars-sized planet idea. <br /><br /><br /><br /><br />

 

[nexium]

Perhaps early Earth had less radioactivite isotopes, and thus had a cool interior which was several percent water all the way to the core. The impact of the Mars size body blasted the small amount of surface water into space, much of which became part of the moon.<br />Earth's center got the radioactive isotopes and is thus still hot today. The moon got/has little radio active isotopes, so the Moon's core cooled, and the moon's surface water sank deep into the Moon's interior.<br />The now hot (because Earth got the radioactive core of the Mars size body) interior of Earth pushed some of the water to Earth's surface where it became our oceans and aquifers. By now the Earth and moon have swept up most of the material that was blown into solar orbit by the impact of the Mars size body. Comets have added perhaps 1% of the water to Earth's oceans. I thought this up, so I can't offer a link. Neil

 

[mariecurie]

I had learned that it was the Earth's rock that mainly went to make up the moon, as cited here by a National Geographic Article:<br /><blockquote><font class="small">In reply to:</font><hr /><p>How the moon was formed remains a mystery. The most heavily favored theories suggest that a giant object—perhaps the size of Mars—collided with the young Earth and ejected a shower of molten rock and part of the Earth's mantle into orbit. This material, the thinking goes, condensed to form a massive ring of orbiting debris that became the moon. <p><hr /></p></p></blockquote><br />After the ring of debris (I think of volcanic clinkers) coalesced to form the surface of the moon, more impacts made craters. Heat rising from within, as with plutons, created volcanos and the surface becam much as we see today.<br /><br />Water, had there been some, would have become steam and spread out in the Earth's atmosphere rather than being ejected, I would guess.<br /><br />The moon was also very much closer to the earth when it formed.<br /><br />Picturing all this is what got me interested in Geology.<br /><br />I have since wondered if the cloud would have covered even the poles -- and if instead of just insulating earths heat it also blocked the light -- and eventually the poles were able to cool enough that the first water precipitated out of the atmosphere. <br /> <br /><i>The very first rain on the earth. sigh..<br />I'd like to have been there for that. <br />To be able to dream of it will have to do...<br /></i>