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earlcp
2002-Mar-10, 01:20 PM
Hello,
Just saw "The Time Machine" which had two big BA mistakes!

First, while using nukes to build big underground bubbles for moon based retirement habitats, the company makes a mistake in thier calculations and blows the moon apart! Some mistake! The energy diffirence between blowing a bubble and spliting the moon in half is far greater than any cost accounting system would allow.

Second, we get a sky shot 800,000 years in the future where we see a hunk of about half of the moon and a second hunk which is about a quarter of the only about four moon diameters apart. Over that much time they should have linked up again.

GrapesOfWrath
2002-Mar-10, 02:01 PM
Second, we get a sky shot 800,000 years in the future where we see a hunk of about half of the moon and a second hunk which is about a quarter of the only about four moon diameters apart. Over that much time they should have linked up again.
Haven't seen the movie, but what if they were orbiting each other? Then, they might not move together at all. I'm not sure how that would happen, though.

Then again, a nuke blowing up the moon?

Chuck
2002-Mar-10, 07:28 PM
I guess Space, 1999 was much more realistic. Their nukes merely send the moon out of the solar system.

kucharek
2002-Mar-11, 07:28 AM
On 2002-03-10 08:20, earlcp wrote:
Second, we get a sky shot 800,000 years in the future where we see a hunk of about half of the moon and a second hunk which is about a quarter of the only about four moon diameters apart. Over that much time they should have linked up again.

Haven't seen it, but I guess if you split the moon into halves, the halves would collapse into some spherical shape, as the gravitational pull is too strong as the halves could keep their semispherical shape. The Moon's too big.
For better descriptions about destroying a moon, read Lem's "Fiasco".

Harald

electroblood
2002-Mar-11, 12:23 PM
Well, I'm new here (Hi!), but when I saw the movie, the way I understood it was that the blast "knocked" the moon from orbit and it was breaking up as it entered our atmosphere. That doesn't sound plausible to me, but then again that's why I'm reading this sight. I don't know anything. I'm being rapidly educated on reality /phpBB/images/smiles/icon_wink.gif

kucharek
2002-Mar-11, 12:38 PM
On 2002-03-11 07:23, electroblood wrote:
Well, I'm new here (Hi!), but when I saw the movie, the way I understood it was that the blast "knocked" the moon from orbit and it was breaking up as it entered our atmosphere. That doesn't sound plausible to me, but then again that's why I'm reading this sight. I don't know anything. I'm being rapidly educated on reality /phpBB/images/smiles/icon_wink.gif

If you would knock the moon out of his orbit so it would get close to the Earth, it would break up long before entering the atmosphere
due to tidal forces (Roche limit).
BTW, when something with a diameter of 3476km
"enters" an atmosphere let's say 30km thick
(the denser part), it shouldn't make a big
difference to the huge body if there is an atmosphere or not...

GrapesOfWrath
2002-Mar-11, 01:24 PM
On 2002-03-11 07:23, electroblood wrote:
Well, I'm new here (Hi!), but when I saw the movie, the way I understood it was that the blast "knocked" the moon from orbit and it was breaking up as it entered our atmosphere.
Well, then, that makes more sense. /phpBB/images/smiles/icon_smile.gif

That doesn't sound plausible to me, but then again that's why I'm reading this sight.
Me too.

I don't know anything.

Nobody really does. Welcome to the BABB, electroblood.

Russ
2002-Mar-14, 01:38 PM
On 2002-03-10 14:28, Chuck wrote:
I guess Space, 1999 was much more realistic. Their nukes merely send the moon out of the solar system.

Actually the amount of energy required to disassociate or deorbit the Moon would probably be more than enough to pulverize it. Phil has a discussion about this in his review of "Space 1999" off os his home page.

In any event, if the Moon did deorbit Earth, there'd be nothing left of life as we know it. The K-T (dinosaur) astroid, that wiped out 40% of the species at the time, was only 10 kilometers across. Something 2300 & change....BOOOOOM! KYAGB.

MULTIVAC
2002-Mar-15, 09:00 PM
I just saw the movie yesterday, and I am pretty sure that they meant that the nuclear explosions "merely" knocked the moon out of orbit, and it was the Earth's tidal forces that broke it up, not the explosions themselves. This is a bit more plausible than nukes splitting the moon in two, although I doubt if it is plausible enough...

As for the two halves coming back together, well, the gravity of the Earth, especially at such a close range, could interfere with that process, I suppose...

The Bad Astronomer
2002-Mar-15, 09:14 PM
On 2002-03-10 14:28, Chuck wrote:
I guess Space, 1999 was much more realistic.

Hey, don't knock Space:1999 (http://www.badastronomy.com/conpix/)!

Silas
2002-Mar-15, 09:51 PM
On 2002-03-15 16:14, The Bad Astronomer wrote:
Hey, don't knock Space:1999 (http://www.badastronomy.com/conpix/)!


When I was a bit younger, I had such a crush on Maya, the shape-shifter... And nearly everyone remembers the sheer horror of the episode "The Dragon."

Then there was "Muuuu-ttaaannnnttt!" and the intermittant natural warp-drive of the moon...

What can I say? I watched it faithfully!

Silas

Rich
2002-Mar-21, 12:03 PM
Hmmm, depending on the amount of force involved in the break-up it would be tough to reassemble all the pieces, wouldn't it? The impression I got from the film was that the debris was being pulled into a ring. Again depending on the forces involved quite possible.

Anyone here ever read a nifty-little piece of Science Fiction by Jack McDevitt entitled Moon Fall? Interesting read on same topic, different cause though... lot's of force involved.

Rich

<font size=-1>[ This Message was edited by: Rich on 2002-03-21 07:04 ]</font>

Bob S.
2002-Mar-21, 05:07 PM
MULTIVAC wrote:
I just saw the movie yesterday, and I am pretty sure that they meant that the nuclear explosions "merely" knocked the moon out of orbit, and it was the Earth's tidal forces that broke it up, not the explosions themselves. This is a bit more plausible than nukes splitting the moon in two, although I doubt if it is plausible enough...

That's more like what I saw too. I just caught the flick yesterday and watched for these crucial scenes.
Firstly, they talked about using 20Mton detonations to blast out underground hollows for a recreational moon base.
Next up, we see the Earth in turmoil, people scrambling to reach underground shelters. It shows the moon, much closer than it should be, cracked, and with debris floating around it. The soldier says that the nukes knocked the moon out of its normal orbit.
BA Alert 1! 20Mton blasts may sound like a lot to your average scientifically illiterate Hollywood writer, but look at the surface of the moon now. How many megatons of TNT would it take to gouge out a crater the size of Tycho? Much much more I would think.
Later we see another shot of the moon, a bit further out, with what looks like a bite taken out of the side, and a cloud of debris around it. Later the morlock leader character talks about the moon falling from the sky, but obviously he's being metaphorical since it is clearly still there though much worse for wear.
BA Alert 2! So clearly the moon wasn't knocked out of the sky or shattered, just knocked into an elliptical orbit where its proximity to Earth would cause earthquakes, tidal waves, and generally hellish conditions. Plus the moon fragments that escaped the moon's gravity might fall to the Earth causing further pandemonium. Would it stabilize itself further out eventually or keep swinging close in for millions of years?
BA Alert 3! After 800,000 years, wouldn't the cloud of debris around the moon form a ring? It would have made for a much more interesting visual in any respect.

Just my thoughts on an otherwise generally entertaining matinee flick.

Wally
2002-Mar-21, 05:31 PM
On 2002-03-15 16:14, The Bad Astronomer wrote:


On 2002-03-10 14:28, Chuck wrote:
I guess Space, 1999 was much more realistic.

Hey, don't knock Space:1999 (http://www.badastronomy.com/conpix/)!


Hey BA. . . Next time, more pictures of the young Swedish gals, ok? /phpBB/images/smiles/icon_biggrin.gif

lonegunman33
2002-Apr-02, 09:26 AM
hmmm i dunno about all that moon stuff but if i knew women in the future look like samantha mumba did i'd spend the rest of my spring trying to travel to the future.my only problem was i didnt get a good look at how far into the future he went before deciding to back and change things.there has to be a reason the sun was so red looking.i guess i missed it.

lonegunman33
2002-Apr-02, 09:26 AM
hmmm i dunno about all that moon stuff but if i knew women in the future look like samantha mumba did i'd spend the rest of my spring trying to travel to the future.my only problem was i didnt get a good look at how far into the future he went before deciding to back and change things.there has to be a reason the sun was so red looking.i guess i missed it.