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James
2002-Feb-04, 12:25 PM
I was driving to school this morning and I was wondering, what would it take to destroy our moon? What would be the effect of the moon being destroyed, after the initial destruction, on the earth?

Also, I was wondering(and here's why it belongs in Lunar Conspiracies), would the same effects happen to the earth if the moon were hollow?

_________________
"It is possible to store the mind with a million facts and still be entirely uneducated." -- Alec Bourne

<font size=-1>[ This Message was edited by: James on 2002-02-04 07:26 ]</font>

ToSeek
2002-Feb-04, 12:54 PM
On 2002-02-04 07:25, James wrote:
I was driving to school this morning and I was wondering, what would it take to destroy our moon? What would be the effect of the moon being destroyed, after the initial destruction, on the earth?


If some of the pieces crash down on us, global annihilation.

If we somehow avoid being crashed on:
- no more tides
- less stable rotation (over the very long term)
- an end to romantic evenings and therefore a reduced reproduction rate. /phpBB/images/smiles/icon_wink.gif

ToSeek
2002-Feb-04, 12:56 PM
Actually, come to think of it, there would still be tides, but induced by the Sun rather than Sun+Moon, so they would be a lot less. I'll let someone else figure out just how much less.

JayUtah
2002-Feb-04, 01:06 PM
It would be darker at night too.

Destroying the moon would require an enormous amount of energy, and it would not be easy to accomplish it without also wrecking life on earth with the debris.

The "seas" on the moon are likely the result of a very impressive impact sometime in the moon's past, which nearly destroyed it. That might give you an idea of how much energy it would take. You would have to break the substance into pieces and impart enough velocity to those pieces to overcome gravity. Even then it is likely some pieces will remain in earth orbit.

The hollow earth theory is an effort to reconcile observed data with a wrong computation of the so-called gravitational neutral point.

The moon's gravitational strength can measured it on earth with sensitive instruments. Its mass can be computed from this value. Its distance is inferred from its orbital period. It's size is deduced from its distance and appearance. Thus an accurate idea of the moon's mass properties does not require visiting the moon. (In fact the reverse is true.) If the moon were hollow, it would mean that the shell would have to be composed of enormously dense yet strong material.

GrapesOfWrath
2002-Feb-04, 03:57 PM
On 2002-02-04 07:56, ToSeek wrote:
Actually, come to think of it, there would still be tides, but induced by the Sun rather than Sun+Moon, so they would be a lot less. I'll let someone else figure out just how much less.
The solar tides are about half the lunar tides, but during full and new moons the two tides augment each other so that the total effect is about one and a half of the lunar value alone. That is known as spring tide. During neap tide, first and third quarters of the moon, the solar effect cancels some of the lunar effect, so the total tide is about half the lunar tide.

So, solar tide alone would be about the same as what we know as neap tide.

Silas
2002-Feb-04, 04:12 PM
Fritz Leiber treated this very nicely in his science fiction novel "The Wanderer." Basically, hyper-advanced aliens come down and eat the moon...

He noted that, in many cases, earth's tides consist of very large bands, across oceans, of standing waves. Now, odd things happen when you interrupt a standing wave. You might catch it at just the right moment to dampen it down to almost nothing... Or you might catch it during one of its self-reinforcing phases, in which case... GIGANTIC TSUNAMI!

(Serious kitchen experiment: slosh water back and forth in a cake pan, creating a standing wave. Then stop the pan cold, doing so at different times during the wave cycle. At some times, the water will just slosh to a stop...and at others it will splash right over the edge of the pan!)

In time, the earth's tides would settle down to solar tides, about 1/3 the magnitude of solar/lunar tides. It would be enough to maintain sea life, and (Leiber speculated) there wouldn't necessarily even be a large number of extinctions.

If the moon were hollow *but retained its full mass* then nothing would be different at all. If the moon were suddenly hollowed out, so that it shone just as brightly, but had very little mass, then Leiber's scenario takes place.

Silas

ToSeek
2002-Feb-04, 05:43 PM
On 2002-02-04 08:06, JayUtah wrote:
If the moon were hollow, it would mean that the shell would have to be composed of enormously dense yet strong material.


I would think that the seismic experiments done on Apollo would have very different results with a hollow Moon.

JayUtah
2002-Feb-04, 06:12 PM
I would think that the seismic experiments done on Apollo would have very different results with a hollow Moon.

True, but how many moon hoax enthusiasts are seismologists? Some of them actually claim that "anomalies" in the Apollo seismograph data prove the massive or hollow moon theories. And that's because they can make those kinds of statements and their gullible readers won't have the inclination or skill to question it.

AstroMike
2002-Feb-04, 06:16 PM
JayUtah: Some of them actually claim that "anomalies" in the Apollo seismograph data prove the massive or hollow moon theories

I have never heard of this. Are people really this stubborn?

ToSeek
2002-Feb-04, 07:03 PM
On 2002-02-04 13:12, JayUtah wrote:

True, but how many moon hoax enthusiasts are seismologists? Some of them actually claim that "anomalies" in the Apollo seismograph data prove the massive or hollow moon theories.


Are some of these HBers really saying
- we didn't go to the Moon
- the data from the seismometers we didn't put there show that the Moon is hollow?

I'm impressed with their logic, if so.

johnwitts
2002-Feb-04, 09:49 PM
There is a book called 'Moonfall, it's Time to Panic' by Jack McDevitt. It's total Science Fiction, but interesting.

[SPELLING!!!!!]

<font size=-1>[ This Message was edited by: johnwitts on 2002-02-04 16:50 ]</font>

Simon
2002-Feb-05, 10:51 AM
Well, I haven't done any energy calculations on it yet, but I think it would be a lot easier to push the moon out of orbit than to destroy it. Not to mention safer.

And if the moon were just reduced to dust and rubble, might it form a ring around the Earth like the rings around the gas giants?

2002-Feb-05, 11:10 AM
<a name="20020205.4:33"> page 20020205.4:33 aka bust Moon
2:one program I ran YEARs ago about gravity?
3:I set up to have two objects from the
4:astroid belt approach Earth . : <2 objects approach
5: the small one colide & the big one pass later
6: and insert the debries caused by the inpact to
7: establish the proper Lunar orbit..
8: I call it the inpactor/injector modle
9: Anyway one version{many} shows that as the
moon sized objects approaches EARTH that Earth splits into two big parts (halves) and the inpact only inpacts one half? it splits about at 2 radii or maybe 4

DJ
2002-Feb-05, 05:24 PM
Hub brings up an interesting point in his models: the earth splits up. The effect of tidal forces on the planet could indeed cause such a breakup it seems.

However, it also depends on how active the earth is at the time. If the earth is still pliable, it is much more likely to change shape, i.e. to an oblate spheroid, than crack.

Seems to lend some credibility that an earth impact somewhere way back in the past created the moon.

I'd love to see some real core samples from the moon.

2002-Feb-08, 03:40 AM
<a name="20020207.9:07"> page 20020207.9:07 aka Energy of Impact
On 2002-02-04 07:25, James wrote: To? 12 OC 8 PAX <pre>
STANDARD 100KM CRATER impactor of KE = 1.488087E+24 JOULE
DIAMETER = 13000 meters DENSITY = 3300 Kg/m^3
VELOCITY = 28 Km/s entry ANGLE = 60 degrees
INPACTOR CREATOR DIAMETER
_________________ VOLUME % 1.2E+12 M^3 ACTUAL 100116 M
MASS % 38.0E+14 Kg APPEARENT 125144 M
(18) KT 3.543064E+11 ERG 1.488087E+31
</pre>

2002-Feb-08, 03:46 AM
<a name="20020207.9:10"> page 20020207.9:10 aka Enery of impact 2
On 2002-02-04 07:54, ToSeek wrote: To? 12 OC 8 PAX
<pre>
8:for an impactor of DIAMETER = 1.3E+08 meters
7: DENSITY = 3000 Kg/m^3 VELOCITY = 25 Km/s
6:entry ANGLE = 90 degrees WITH KE = 1.078449E+36 JOULE
5:INPACTOR CREATOR DIAMETER
4: VOLUME % 1.2E+24 M^3 ACTUAL %379461632 M
3: MASS % 34.5E+26 Kg APPEARENT %474327040 M
2:(18) KT 2.567736E+23
1:(24) Rh 1.078449E+18 (24)Cr 379461 (24)Ri 1054060
--(42) Ob 1 REMOVED % 5.4E+24 M^3
9:13 P.M. PST So the Obliteration kicks in at
about 24^24 power in terms of kiloTons
or some where around 10 to the 36th power Joules give or take a dozen or 2

GrapesOfWrath
2002-Feb-08, 03:49 AM
On 2002-02-07 22:46, HUb' wrote:
9:13 P.M. PST So the Obliteration kicks in

Well, it was fun while it lasted, wasn't it?

Chip
2002-Feb-08, 08:16 AM
If a fast moving big heavy asteroid hit the moon at a trajectory that shattered it, but with debris moving away from the earth, we might end up with a ring ala Saturn.

As far as being hollow, there may be large caverns in the moon. I'm not sure anyone has proven that itís anywhere near being hollow. It does tend to resonate when hit by something. Instruments left by the Astronauts indicated this.

aurorae
2002-Feb-08, 03:57 PM
On 2002-02-08 03:16, Chip wrote:
As far as being hollow, there may be large caverns in the moon. I'm not sure anyone has proven that itís anywhere near being hollow. It does tend to resonate when hit by something. Instruments left by the Astronauts indicated this.


Umm, no one has proven that it is hollow because it is not.

Lots of things vibrate. Seismologists got a pretty good idea of what the interior of the moon is composed of by analyzing the results of the experiments.

Large caverns? Well, there might be some near surface lava tubes (which are also well known on Earth, of course).

Mnemonia
2002-Feb-11, 04:57 PM
On 2002-02-08 03:16, Chip wrote:
If a fast moving big heavy asteroid hit the moon at a trajectory that shattered it, but with debris moving away from the earth, we might end up with a ring ala Saturn.


That would take a huge amount of kenetic energy, and the positioning would have to be just right - in other words the object would have to approach the Moon at the correct angle (as well as be a practically head-on hit) and the moon has to be in the right stage of its orbit. Otherwise the collision creates debris that the Earth immediately flies through, or wil fly through about a year later. About the only way to destroy the moon with a single large asteroid is to blow it (or what's left of it anyway) clear out of Earth's orbit and immediate gravitational influence.

Of course any object that large, dense, and massive would probably foul up Earth's orbit anyway, so maybe its a moot point.

johnwitts
2002-Feb-11, 09:37 PM
Otherwise the collision creates debris that the Earth immediately flies through, or wil fly through about a year later.

Not necessarily. An object that would shatter the Moon would do just that, shatter it. This does not mean that the separated bits would necessarily go anywhere. The energy of impact would go into the shattering process and would therefore not move the bits into a significantly different orbit. We may end up with a ring, or if there are sufficiently big bits left, they may reform into a 'new' moon.

James
2002-Feb-12, 01:12 AM
On 2002-02-11 16:37, johnwitts wrote:
Otherwise the collision creates debris that the Earth immediately flies through, or wil fly through about a year later.

Not necessarily. An object that would shatter the Moon would do just that, shatter it. This does not mean that the separated bits would necessarily go anywhere. The energy of impact would go into the shattering process and would therefore not move the bits into a significantly different orbit. We may end up with a ring, or if there are sufficiently big bits left, they may reform into a 'new' moon.

Would the 'new' moon be smaller than our current one or would the material from the asteroid and whatever was left of the Moon be coalesced into a moon either the same size or bigger?

johnwitts
2002-Feb-12, 01:27 AM
I guess we'll never know unless we try it! It's pretty hard to hit a planet or moon. By definition, the gravity that pulls an object towards a planet or moon will accelerate that object to escape velocity, unless another force interferes. In the grand scheme of the solar system, the Earth and Moon are pretty small targets.
We've got a small ring at the moment, made from comsats at 22,500 miles above the equator. They show no tendency to merge into one big lump. Maybe over time...

Further thinking...My best guess is that an object with enough energy to knock the Moon out of orbit would contain more than enough energy to shatter it. Imagine trying to hit a ball on the Moon so that it left the Earth Moon system altogether. You'd have to hit it so hard, that no matter what material it was made of, you'd bust it into pieces first.

2002-Feb-12, 07:55 AM
<a name="20020212.1:21"> PAGE 20020212.1:21 aka Crater.bas
On 2002-02-07 22:49, GrapesOfWrath wrote: To: 2-2-12


On 2002-02-07 22:46, HUb' wrote:
9:13 P.M. PST So the Obliteration kicks in

Well, it was fun while it lasted, wasn't it?
[/quote] YES, yes it was, I sspent a lot of time revising a BASIC
program I found at skypub, so it would Print out obliterations
http://www.skypub.com/resources/software/basic/basic.html