When the Moon in the Sky/ Means We're All Gonna Die/ That's an...Impact

Steven Dutch, Natural and Applied Sciences, Universityof Wisconsin - Green Bay
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Hot Babe Scientist. Linus Pauling never looked like this. Hollywood is now capable of dealing with a woman scientist. Someday they will be capable of portraying a plain, middle-aged or overweight woman scientist.


Hunk Scientist. Linus Pauling never looked like this, either. Stephen Hawking may be a great heroic role model, but good looks sell tickets.


High Caloric-Intake Monster. Large animals eat a smaller fraction of their body weight each day than small ones, a manifestation of surface to volume ratio. Hollywood critters, on the other hand, eat like shrews.


Pompous Ass who Pays With His Life. The pig-headed boss or political figure who refuses for selfish reasons to listen to warnings and gets killed. Occasionally it really happens; the governor of Martinique refused to evacuate when Mont Pelee began erupting 1902, and died in the resulting catastrophe. So did 30,000 innocent people.


Superfluous Kids. Kids (generally repugnant) who serve no real dramatic purpose except to generate audience sympathy. I root for the monsters, especially when the kids do something stupid after they've been told not to.


Cookie Crumbs Have No Calories. And large objects (like asteroids) cease to exist once they're broken up.


No Other Scientists in the World. Apart from the two or three characters in the film, nobody else in the entire worldwide scientific community is aware anything unusual is going on. Nobody else seems to be aware of the huge tidal waves, plagues of locusts and frogs, rain of blood, global slaughter of first-born, etc.

Impact (HBS. HUNK, SK, NOSW)

In a Peanuts cartoon, Linus laments that the days are long in the summer. If they were long in the winter, he explains, we could stay outdoors longer and enjoy it. Lucy responds "I'll say this for you. The quality of your stupidity is improving."

You just can't make a non-stupid movie about the Moon colliding with the Earth (should I have issued a spoiler alert?) Nevertheless, the quality of Hollywood's stupidity is improving. The cast is pretty good, the acting is decent, the effects are pretty good and I was only tempted to bang my head on the wall intermittently - in Part I. The movie even involves Europeans as well as Americans. That may be because it was originally made in Germany, explaining why the writers were more aware of the existence of intelligent life in Europe.

Part I of the movie (aired June 21, 2009) opens with the greatest meteor shower in 10,000 years as seen in both America and Europe. The meteors are realistic looking, and amazingly enough, emanate from a radiant, as well as converging on the opposite side of the sky. I'm sure that's the work of the CGI software rather than a deliberate script choice. Even so, color me impressed. Offering commentary on the sky show is Maddie Reese (Natasha Henstridge), an expert on heavenly bodies. She's also an astronomer. Watching from home is Alex Kinter (David James Elliott) a former colleague of Maddie's. He's recently widowed (wink, wink, nudge, nudge) and has two kids who are more or less indistinguishable from the furniture. Also their grumpy grandpa (James Cromwell), who is afraid to leave the house ever since Babe was converted into BLT's.

All of a sudden, observers note a larger object on collision course with the Moon. It was "hiding" behind the main meteor swarm and invisible. The first faint whiff of silliness. But it's 19 kilometers across. It plows into the Moon. and even though the meteors streaked silently across Earth's sky, the meteor screams audibly into the Moon, making a very loud explosion. Ejecta from the blast fly out at 6000 kilometers a minute. Who uses kilometers per minute? Why not 100 kilometers per second? Scientists around the world express incredulity, as well they might. A big impact will fling material out of the crater at velocities comparable to the incoming object. So if the object hit the moon at 30 km/sec, ejecta might fly out at 30 kilometers a second, not 100. Anyway, at that speed, it only takes the objects an hour to reach earth, although in the movie the interval seems to be at most a couple of minutes, since there's no hint of a hiatus.

One big chunk, 100 meters across, is headed for the Indian Ocean. Now a chunk that big will make a crater two or three kilometers across and a few hundred meters deep. In other words, it will punch a hole in the water. At that speed there won't be much difference between hitting water and hitting rock. How to do this on screen? Well, the asteroid hits like a big rock being thrown into the water, and looks like somebody threw a big rock into the water. Then, below the surface, it explodes and throws up a huge dome of water like in the World War II submarine movies. Then it makes a tsunami. Give it a B for effort.

But weird stuff is happening. Tides are doing bizarre things. Eventually, meteorite hunter Roland Emerson (Benjamin Sadler) is led to a crater made by a chunk of the object that hit the Moon. It's so magnetic it causes a geologist's pick to fly violently at it from several meters away, but only after the pick is taken out of his knapsack. See, in Movie Magnetism, magnets can be blocked by a single layer of cloth. Roland eventually concludes the meteor is a chunk of a brown dwarf. Maddie, meanwhile, has renewed her contact with Alex to try to understand the mounting weirdness. We learn that Alex was involved with research at NASA on an anti-gravity device (wink, wink, nudge, nudge) but "it wasn't practical."

Supposedly the apparatus only levitated a frog. I guarantee you, if anyone comes up with a way to alter gravity, even on the scale of one atom, it will be practical. Or we will find a way to make it practical. If you can levitate a frog, you can levitate an aircraft carrier. The ability to control gravity would be so immensely useful we would spare no effort or expense to make it work. It will also get the discoverer a trip to Stockholm for a Nobel Prize.

The reason the Moon is doing weird things is because the meteor that hit it is actually brown dwarf matter, and weighs "twelve sextillion tons." None of that "one point two times ten to the twenty-fifth kilograms" that a scientist would actually say. So this meteor is actually twice as massive as the earth. Apparently it obeys the Wile E. Coyote Law of Gravity and only exerts gravitational pull once people realize it has mass, just like Wile E. Coyote can run on thin air until he realizes he's run off the cliff.

A brown dwarf is intermediate between a planet like Jupiter and a normal star, not quite hot and dense enough to start nuclear fusion. So why it has the staggering density it supposedly has is a mystery. Maybe neutron stars were old hat and brown dwarfs are the buzzword du jour.

If this object really had twice the mass of the Earth, there is no way it would have gotten deep into the Solar System unnoticed. For one thing, it would have affected the orbits of the other meteors so much it would have stood out like a sore thumb. Every interplanetary probe in the inner solar system would have shown tracking errors. There would have been noticeable errors in the positions of asteroids and planets. Since the object weighs 160 times as much as the Moon, it would have pulled the Moon toward it, not the other way round. With that kind of mass, it should have plowed deep into the Moon if not all the way through, and released enough energy to melt the Moon.

This is fun. The object weighs 1.2 x 1025 kg and hit the Moon at, say, 30 km per second, or 30,000 m/sec. That means its kinetic energy was 1/2 x 1.2 x 1025 x 30,000 x 30,000 = 5.4 x 1033 joules. It takes roughly 400,000 joules to melt a kilogram of rock (this is one of the factoids I toss out when I want guests to go home), so this thing packed enough energy to melt 5.4 x 1033/400,000 = 1.3 x 1028 kilograms of rock. Now the Moon weighs 7.3 x 1022 kilograms, so the impact has enough energy to melt the Moon 150,000 times over. It has enough energy to melt the Moon and the massive asteroid about 1000 times over. There's way more energy than it would take to vaporize the asteroid plus the Moon. Also, the total energy released would be equal to the Sun's total output for several months, but at only 1/400 the distance.

The Moon is 400,000 kilometers away. By the time the radiant energy hits Earth, the energy is spread over a sphere 400,000 kilometers in radius with area 4pi(400,000)2. One square meter on Earth intercepts 1/4pi(400,000 x 1000)2 = 5 x 10-19 of the energy. Let's assume it takes 100,000 seconds, a little over a day, for the energy to be released. That's 5.4 x 1028 joules/sec = 5.4 x 1028 watts. Each square meter on the earth will receive 5 x 10-19 of that, or 2.7 x 108 watts. The only problem is that the energy the Earth gets from the Sun now is 1400 watts. We will get 200,000 times as much heat from the impact as we get from the Sun. Talk about global warming. Even James Inhofe won't be able to deny that.

How hot will it get? There's a nifty law, the Stefan-Boltzmann Law, that says temperature is proportional to the fourth root of radiation. A planet twice as hot as the Earth would be getting 16 times as much radiation as the Earth. So with 200,000 times as much radiation, the temperature would be 21 times as high (21 x 21 x 21 x 21 = 200,000). Temperature is on the Kelvin scale, with zero at absolute zero. The earth's average temperature is 290 K now, which would increase 21 times to 6000 K - as hot as the surface of the Sun. For a whole day. So nobody will be around to worry about the eventual fate of the Moon.

If the impacting object is more massive than the Earth but only a few kilometers across, it will have a density billions of times greater than water. My guess is something like that would punch through the Moon like a bullet through a watermelon.

Also, since the Moon now outweighs the Earth, the Earth now orbits the Moon. Actually, both orbit the center of mass of the system, which is two thirds of the way from the Earth to the Moon. And, since the Moon is now 160 times heavier, its tidal effects on the Earth are 160 times greater. High tides should completely cover Florida. That ought to shut up the tourists in Orlando who regularly complain their hotel room doesn't have an ocean view. We'll grant the Hollywood dispensation that the oceans have not been completely vaporized. After all, the asteroid didn't have mass until people realized it had mass.

The weirdness (and silliness) escalate. The Moon periodically changes its orbit and the orbit becomes more elliptical. But not your standard Kepler's Law orbit with the earth at the focus. No, this orbit has the earth at the center, and each time the Moon reaches the near points on either side of the orbit, weirdness ensues. Objects and people are lifted into the air and violent electrical discharges take place. Alex finally determines that the magnetic field of the brown dwarf matter in the Moon is interacting with the earth's magnetic field. Why does it affect people? "Because we're all made of the same electromagnetic energy." This was one of the points I succumbed to the temptation to bang my head on the wall.

As one of the magnetic storms pummels Europe, and North America prepares to be hit, Roland calls from Europe with even worse news. The interference between the magnetic fields is causing the Moon to spiral in to the Earth. This might actually happen if the fields were each millions of times stronger than the Earth's magnetic field, except the motion of your electrically conducting blood in the Earth's magnetic field would induce powerful electric currents in your body. It would probably also interact with the currents to produce powerful torques and make your body move in funny ways. Anyway, the Moon will collide with Earth in 39 days.

Maddie explains to the President (a very Al-Gore-ish Steven Culp) that a 9 kilometer asteroid killed the dinosaurs and a 90-kilometer asteroid would vaporize the oceans and sterilize the Earth. When the Moon collides, she says, there won't be a planet Earth. Well, that part is certainly true, given the energy that the asteroid would have generated merely colliding with the Moon. But what about that 90-kilometer asteroid?

An asteroid 90 kilometers in diameter would have a volume of 4 x 1014 cubic meters, and if it's a rocky asteroid, it will weigh about 3000 kg/cubic meter. So its total mass is 1.2 x 1018 kilograms. If it hits at 30 km/second (30,000 m/sec), its kinetic energy will be 5.4 x 1026 joules. Water requires about 2.5 million joules per kilogram to boil, so there's enough energy to boil about 2 x 1020 kilograms of water. The oceans weigh about 1.4 x 1021 kilograms, so only about a seventh of the oceans will boil away. The reason the oceans will boil is that the impact will vaporize about 1019 kilograms of rock - the asteroid itself plus ten times or so as much crustal rock. That's about twice the mass of the atmosphere, meaning Earth will have a short lived atmosphere of vaporized silicates. Not as short lived, however, as the surface organisms blanketed by it. After the silicate vapor condenses, we will be left with a dense atmosphere of live steam, which will be the only live thing left on the surface. Just maybe, life in the deep oceans will survive.

Remember how I said the quality of Hollywood's stupidity is improving? Scratch that. Part II, aired June 28, 2009, pushed the silliness envelope to the breaking point.

The magnetic levitation disturbances hit North America. At sea, a container ship levitates and then falls back into the water. As a break from all the spectacular, realistic computer graphics effects we see in movies these days, this scene offers really crappy special effects. It looked like the kind of thing video gamers record on their computers and post on YouTube.

Meanwhile the Superfluous Kids and Grumpy Grandpa are headed for Washington when their car is levitated, then smashed back to earth. They start walking and come upon a food stash in a deserted restaurant. The owner of the stash accosts the kids and Grandpa knocks him out cold. Then Grandpa starts having heart trouble.

In fact, this movie is filled with superfluous characters. It's as if the producers said "We have lousy science and cheesy special effects. What's missing? I know! We need incompetent character development as well." We have the kids and Grandpa. Then the owner of the food stash turns out to be a sullen loner (his disposition not improved by being knocked out). After Grandpa dies, he drives off, leaving the kids stranded, then comes back for them. Why so sullen (apart from the getting knocked out bit)? Bad time in combat? His dog got run over? His wife left him? We never find out. Why did he have a change of heart? We never find that out, either.

Then there's Roland's girl friend, Martina. She's headed for Munich to see her mother, and a seedy lounge lizard type tries to pick her up on the train. Then the train gets levitated, and in the aftermath, he actually turns out helpful. By the way, I don't care how bad the disaster is - the Germans would never put up tents as haphazardly as we see in the aerial view of the disaster scene. Because they're Germans, that's why. Anyway, Lounge Lizard helps Martina get a ride out on a supply truck. Why? Who is this guy? We don't even get to see if he actually paid the truckers the bribe he offered. And Martina is principally there to create emotional connections for Roland. Because risking your life on a space mission to save the planet isn't gripping enough. I will say that Martina and Roland have the most real personalities of any of the characters.

And we also have Maddie's scuzzball ex-husband, a down on his luck reporter with the silliest looking goatee I have seen in a long time. It seems to have been inspired by Gary Oldman's character in Fifth Element. He senses something is afoot, gets a leak about the impending lunar collision, and goes public. Because there are no other scientists in the whole world interested in all the cataclysms. And of course there are no conspiracy theorists and doomsday prophets on the Internet. So Maddie's ex breaks the news. Then what? Does he get his big break into the big time? Does he end up floating face down in the Potomac? This is the last we see of him.

The White House is in a tizzy. Maddie and Alex struggle to come up with a plan. The scientific nadir comes when someone mentions stabilizing the Moon in the Earth's L4 or L5 points. The only reason the Earth has L4 and L5 points is because of the Moon, and they are always in the Moon's orbit 60 degrees ahead of or behind the Moon. Getting the Moon into the L4 or L5 point is like trying to jump onto your own shadow. The military comes up with a plan to blast the brown dwarf mass with nukes, but the plan fails. Apparently it only takes a few minutes to get to the Moon, since a display with 15 minutes to impact shows the rockets barely a quarter of the way to the Moon. Then Alex says "Remember the anti-gravity thingy from Part I?" The European Space Agency had been all set to launch a lunar mission, so all we need to do is load the anti-gravity gizmo and a missile launcher onto the moon rocket and take off. Because lunar missions have loads of extra room and can easily carry tons of extra gear the size of a car. We'll just take fewer sandwiches. The President insists Alex and Roland go along since only they have the expertise to make the crucial decisions.

The plan is to launch a missile into one of the deep fissures created by the impact, then have the missile detonate and create a plasma jet penetrating to the Moon's Core. Then the anti-gravity device, connected to the missile by wire, will fire, magnetize the Moon's core and repel the brown dwarf back into space. This all has to be done at the "apex peak" of the Moon's orbit, because "apogee" is too technical, I guess. If the brown dwarf is expelled then, it will be captured by the Sun's gravity. See, there are signs out in space saying "now entering Sun's gravity." If the missile is launched too late, the brown dwarf will hit the earth.

So Alex and Roland team up with Sergei the Russian pilot and Courtney, the American co-pilot, and they launch aboard a Soyuz rocket. Now the Soyuz is a technological wonder and dependable as can be, but it's not enough for a lunar mission, and there's no indication that the spacecraft will dock with an already orbiting lunar vessel. They arrive at the Moon about 20 minutes after launch. Now - this is explicitly mentioned in the movie - thanks to the extra mass, gravity on the Moon is twice as strong as on the Earth. Yet apparently no modifications were needed on the lunar lander, and the lunar hovercraft has a motor about as big as a Fourth of July bottle rocket. While Alex sets up the anti-gravity doohickey, Courtney and Roland scout the fissures for the best place to drop the missile. The lander is damaged and crashes in the fissure. Courtney is dangling from the edge of a cliff and, despite Roland's best efforts, she falls. Mission Control is treated to a video of her screaming all the way down. For some reason, the astronaut's helmets have lights inside, which would seem to make it impossible to see anything between glare, reflections, and ruined dark adaptation.

Roland is stranded and Martina tearfully watches from Mission Control. Because someone sacrificing his life to save the human race just doesn't have any emotional impact unless we see somebody crying.

Despite Alex's protests, Sergei launches the missile in the nick of time and takes off. Now it took a Soyuz rocket to get them off the Earth, but the tiny rocket of the lunar lander is enough to get them off the Moon even though the gravity is twice as strong. The missile detonates and the brown dwarf is launched into the sun, like a, well, make your own disgusting comparisons. Oddly enough, Newton's Third Law doesn't seem to apply here, since firing a mass 160 times that of the Moon at high speed in one direction doesn't seem to have the slightest effect on the Moon's orbit. But the explosion does split the Moon in two. The world is saved.

The movie closes with an epilogue about how all hostilities on Earth have ceased. Until we start arguing about whose deity intervened to save the planet. I give it a week.

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Created 5 August 2008, Last Update 24 May 2020

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