Impact

[RAF_Blackace]

Watching it on Sci-Fi Channel. If you have seen it its not bad as a story, a bit better than many stories. It does go a bit far though with some strange assumptions.

WARNING SPOILER:

Story is about a meteor shower that is the best display in years. Suddenly, in amongst the thousands of objects being tracked, one is spotted that is heading straight for the moon, not very big, but interesting non the less..

It impacts, making massive damage. Some debris is thrown towards the Earth, impacting several hours later.

Everyone feels lucky because after a few days everything seems to calm down, apart from some odd weather artefacts. Except that one scientist discovers a part of the debris from the moon in a very unrealistic crater. It turns out to be a bit of a brown dwarf, and immensely dense.

They run calculations and the asteroid that struck the moon had a mass twice that of the Earth, it is now part of the moon. The two objects are pulling each other together and the Earth is getting wilder by the day.

Part 2 is on Next week. If you've seen it don't tell me how it finishes. If you haven't seen it I apologise for the spoiler.

[PraedSt]

So now we're orbiting the Moon?

[RAF_Blackace]

So now we're orbiting the Moon?

Well you would have thought so, but apparently not, the moon is simply spiralling closer and closer to the Earth. Tides were affected first so at least the sudden huge mass increase was reflected in that aspect.

After the impact they said the Moons orbit was closer but had stabilised. When they realised the impact was from a brown dwarf some days later, they said they should check the Moons orbit again, as no had done so since the impact, as if. They said it was even closer but had stabilised again, then it suddenly started getting closer again, then it once more stabilised. Newton was turning in his grave.

Also the Earth experienced a huge increase in magnetic activity. The part that impacted the Earth (no bigger than your fist) displayed an enormous magnetic field. It was lifted by a crane whose SWL was probably about 50 Tons. But they used webbing which has a SWL of only about 5 Tons.

How heavy would a fist size piece of brown dwarf be ? millions of Tons I would think.

Made me laugh that the piece that hit the Earth despite it arriving from the moon in only a few hours at immense speeds and being so dense made an impact crater only about 10Ft deep. Woops.

[Jeff Root]

Did they actually say "brown dwarf", or did they say "white dwarf"?
White dwarf stars are famous for their enormous density. Brown dwarfs
are not.

Of course, in either case -- white dwarf or brown -- the density is due to
the enormous mass of the body. If a small chunk of the body were flung
off into space, it would immediately expand, becoming less dense.

On the other hand, back in 1985 I wrote a page explaining Star Trek's
dilithium crystals, in whch I had them originating in white dwarf stars
which subsequently exploded. The unusual combination of conditions
which allowed dilithium to be created and then spewed out into space
made it very rare. At that time the properties of dilithium had not yet
been defined in the TV series, so I defined them, and mine were much
superior to those put forward in ST-TNG. I had the dilithium be part
of the sensor system, required to navigate space at warp speeds.
Without dilithium, warp travel was essentially blind. You could only
see something in your path ahead of you when you hit it. Deflector
shields could not extend forward from the ship at warp speeds without
dilithium. A problem with dilithium was that it weakened every time
it was moved at warp speeds. The higher the warp facter, the greater
the damage. A crystal could only stand one or two excursions to warp
nine or above, before it was ruined. And it was useless to store spares.
Every crystal on the ship was affected by warp speed, whether it was
in use at the time or not.

Sorry I went off-topic already. :)

-- Jeff, in Minneapolis

[Paul Beardsley]

I too watched Impact. I found it surprisingly enjoyable, not least because it gave the impression that characters were being affected around the world. A lot of the action was represented by short illustrative sequences and quite a lot of talk about what's going on offstage and beyond the budget - a bit like a Greek play.

I also liked the fact that, although the science is largely a load of horses' hooves, the writer clearly knows some science, and is grounding the nonsense science on the reasonably good science. Unlike, say, most of new Doctor Who which gets it absolutely wrong from start to finish.

[Rhaedas]

Wanted to wait until you commented on it before I mentioned the reviews I had read. Was the acting worth watching, even if the science went a bit out there later on?

I like the premise, that something so familiar to us becomes a threat. Not sure why they had to use "brown dwarf" material though, just have the moon shield us from a very large threat, but in doing so become one itself. Then they could have turned to a more "When Worlds Collide" scenario.

Although WWC had a place to escape, that would have to be written in somehow too...

[hhEb09'1]

Well you would have thought so, but apparently not, the moon is simply spiralling closer and closer to the Earth. Tides were affected first so at least the sudden huge mass increase was reflected in that aspect.The piece that stuck in the moon had a mass twice that of the Earth? The Earth is 80 times the mass of the moon, so the tides on Earth would suddenly increase 160 times. Coastal cities would be completely inundated, right?

[Jeff Root]

The piece that stuck in the moon had a mass twice that of the Earth?
The Earth is 80 times the mass of the moon, so the tides on Earth
would suddenly increase 160 times. Coastal cities would be completely
inundated, right?
Not necessarily. I think the direct effect of the Moon's gravity on
Earth's oceans is a bulge only a couple of inches high. (A search,
even just on BAUT, would probably turn up the exact figure, but I'm
not very good at searches and, more important, I'm extremely lazy.)
The large tides along the coasts are due to that couple of inches
of water piling up on the continental shelves (shelfs?) as it moves
toward the shores. It might pile up 160 times what we have now,
or it might pile up more or less than that. I suspect it would be less.

In any case, the length of the month would fall to less than six days,
I'm pretty sure, and Earth would definitely orbit the Moon, nomatter
what Ken says about relative motion or what anybody says about the
location of the barycenter!

However, if a small body with a mass twice that of Earth struck the
Moon, unless it was a black hole, it is made of a form of matter for
which there is no hint of a suggestion that it exists.

If it is a black hole, it should pass right through the Moon and go out
the other side, but seriously altering the Moon's orbit around Earth.

If it is a black hole and doesn't pass right through, but gets stuck
inside the Moon, then I think the Moon would be consumed in as little
as a few hours. Except for the small explosion at the entry point,
the Moon might look normal for the first few hours, then parts of the
surface would begin to cave in, and suddenly the whole Moon would
implode and vanish. There wouldn't even be a cloud of dust.

-- Jeff, in Minneapolis

[sarongsong]

"Impact (http://www.imdb.com/title/tt1227637/)" [2008]

US TV Schedule:
Sun. June 21 9:00 PM ABC
Sun. June 28 9:00 PM ABC
- IMDb

[Maha Vailo]

Of course, in either case -- white dwarf or brown -- the density is due to the enormous mass of the body. If a small chunk of the body were flung off into space, it would immediately expand, becoming less dense.

So a chunk of brown dwarf (of any size) that flew out into space would become a cloud of brown dwarf once it reached Earth and would thus be rendered harmless.

- Maha Vailo

[ChunkyLover53]

If they had said chunk of neutron star would it have been more believable? Its my understanding that neutron stars are composed of neutrons, which are very stable, so
you wouldn't have to worry about the pressure caused by the Pauli exclusion principle as you would in white dwarfs .

[MichaelB]

How many errors are there in their portrayal of electromagnetism? It seemed like Velikovsky was their science advisor. I'm no expert on electromagnetism, though- does anyone know what their specific mistakes were?

[Paul Beardsley]

I watched half an hour of part 2 but couldn't sustain an interest. Part 1 felt as if some thought had gone into it, but part 2 became overwhelmed with technobabble and random threats.

And why is the gravity thing so selective? Grab the ship but not the surrounding water?

I might watch the rest later... then again, I might delete it unwatched.

[Paul Beardsley]

Well, I switched my brain off and watched the rest. Quite enjoyable nonsense.

[eburacum45]

If they had said chunk of neutron star would it have been more believable? Its my understanding that neutron stars are composed of neutrons, which are very stable, so you wouldn't have to worry about the pressure caused by the Pauli exclusion principle as you would in white dwarfs .

I think that probably isn't the case. The stuff inside neutron stars is a very dense, very hot fluid, which would expand into a gas of neutrons if removed from the star. Single neutrons outside of a nucleus or a neutron star have a half-life of 15 minutes or so, and would decay into ptotons or electrons. Or that is how I understand it, anyway.

If I'm right, there isn't any stable form of ultradense matter that could be extracted from a neutron star. Or a brown dwarf for that matter.

[Demigrog]

If something twice the mass of Earth hit the moon, it would keep right on going; the moon has insufficient mass to stop it. The energy released would be huge and the moon get turned into a molten blob. Some material would certainly get ejected, but probably with sufficient velocity to escape Earth for the most part.

The orbital effects on Earth and the Moon would be huge and hard to predict; even if nothing physically collided we'd probably wind up in the sun or ejected from the solar system (like in the recent Nature (http://www.gearlog.com/2009/06/earth_and_venus_could_smash_to.php) article), even if the "object" was a diffuse gas cloud twice the mass of Earth.

[Maha Vailo]

^ How long would it take for Earth to fry/freeze in such a scenario?

- Maha "look out world!" Vailo

[Gandalf223]

So a chunk of brown dwarf (of any size) that flew out into space would become a cloud of brown dwarf once it reached Earth and would thus be rendered harmless.

And the entire planet would be covered with some kind of brown goo.

Sorry, I didn't mean to start talking politics! :whistle:

[MichaelB]

Maybe I'm missing something but their brilliant plan to save the earth doesn't make much sense. They're going to magnetize the moon while it's moving away from Earth so that the moon and the brown dwarf repel each other. Then the brown dwarf will be shot into the sun. But won't the moon also be shot in the opposite direction,i.e. toward the Earth?

[Stunrunner]

Wow...I'm watching part 2 right now, it's like a train wreck, so horrible but I just can't look away. I feel insulted that a show with this many awful science premises made it to primetime. Now people are going to watch this and come to us astrophysicists and ask, "I'm scared, could this really happen?"
"No, this can't really happen. If it did, it'd be a movie. A really horrible movie."
I probably won't get all of the errors, just the main ones:
The moon does NOT have a magnetic field.
IF a brown dwarf did get anywhere close to Earth, we'd see it coming. They still have significant infrared emission.
IF something massive impacted the moon, the lodging and geological processes they're talking about take millions of years, because we're talking about rocks here. If anything, the impactor would either shatter on the surface, or shatter the moon, rather than fracturing it.
IF such an impact altered the course of the moon, it's resulting orbit change, IF becoming more elliptical, must have the Earth at one of the foci, not halfway like they seem to "calculate." Plus, improper use of Kepler's 3rd law.
"Anything is possible now..." - I'm sorry, but this is PHYSICS. The laws of physics don't change. They're laws.
Gravity is not localized, ever. It will always follow the inverse square law. It also cannot pick and choose what to act on (an oil tanker floats in the air but not the water around it?).
Axis peak = Apahelion. PLEASE just use the right words at least.
I'm not even going to comment on "plan B" to save the moon, it's just ridiculously confusing and an excuse the throw out popular buzzwords like "carbon nanotubes" and "space elevator."
If we are supposed to suspend disbelief this far, it should be set in a non-real universe, ideally not around Earth.
If I've errored in any of the details, please feel free to correct me.

[Jeff Root]

I haven't even seen it and I feel queasy.

-- Jeff, in Minneapolis

[Paul Beardsley]

Well, after four years of revived Doctor Who, Impact looks like a university-funded science documentary in comparison.

[darkhunter]

Sounds like the cheesy end of the world disaster movies I like to watch....

[Celestial Mechanic]

Welcome to BAUT Forum!

Wow...I'm watching part 2 right now, it's like a train wreck, so horrible but I just can't look away. I feel insulted that a show with this many awful science premises made it to primetime. Now people are going to watch this and come to us astrophysicists and ask, "I'm scared, could this really happen?"
"No, this can't really happen. If it did, it'd be a movie. A really horrible movie."
I probably won't get all of the errors, just the main ones:
[Snip! All good]
Axis peak = Apogee. PLEASE just use the right words at least.
[Snip!]{My correction}
That was my main beef, their coinage of the term "axis peak" for apogee. Didn't they hire any consultants? If that had any science consultants, did they pay them? Maybe they should ask for their money back? :think:

And it's not like "apogee" is some esoteric science term, either. I'll bet most First World people (once you remove the people that the Jaywalking segment of the Tonight Show always seems to find) know what an apogee is or could have figured it out from the context. This was a truly, truly stinky movie. Or to use a term I dropped in another thread, USDA Certified Grade AAA twaddle.

[jokergirl]

Wow, I liked the first part but the second one is just so full of technobabble I actually just yelled "Astrophysics does not work that way!" at the TV.

I might just switch back to rewatching Episode II... which is less painful, you think?

;)

[Doodler]

How heavy would a fist size piece of brown dwarf be ? millions of Tons I would think.


Its a bit more complicated than that. The material of superdense objects is only so dense because the enormous amounts conglomerated together compress it via gravitation.

Once "blown off" from the rest, the dense matter, especially in a liquified state, would become undense in a REAL hurry. Something I saw on the metallic hydrogen core of Jupiter was used as a hypothetical example, where a teaspoon of the stuff, weighing in at hundreds of thousands of tons, were brought to Earth and released, it explosively expanded with the force of a hydrogen bomb.

[xfahctor]

I know this is old, but it was on again last night and I saw it for the first time, both parts. All I can say is......wow (not a good wow). The one piece of REALLY REALLY bad science I did not see addressed here involved the object that hit the moon. They called it a piece of a "dead star", yet used the term "brown dwarf" rather than "white dwarf". Surprised no one else here caught that.

[Van Rijn]

I happened to switch over to that show for about five minutes when something hit the Moon and pulverized it - the entire Moon. After that, they had the U.S. President calling a scientist and asking about effects. That's where the scientist should have been saying it was time to say goodbye, if they were still rational and talking. If the Moon was shattered I can't imagine how the Earth would avoid at least enough debris to cause human extinction, but the Earth only had relatively minor impacts in the show.

Anyway, that was enough for me to decide not to watch further.

[Maha Vailo]

Something I saw on the metallic hydrogen core of Jupiter was used as a hypothetical example, where a teaspoon of the stuff, weighing in at hundreds of thousands of tons, were brought to Earth and released, it explosively expanded with the force of a hydrogen bomb.

Wow. How much destruction would this cause - would it be a city-buster, or an extinction event?

- Maha Vailo

[Elukka]

Well, you couldn't exactly bring it to Earth since the moment you relieve it of pressure by digging it out it reverts to your normal garden variety hydrogen. Unless you could convince it to stay metastable... In which case it'd make a damn good rocket fuel!