By Phil Plait | March 31, 2011 12:30 pm

I have a new article up on Blastr, the SyFy channel’s web site for news and info and scifi-y stuff.

The article is about asteroid impacts, and the lack of Hollywood accuracy thereof. I take a typical movie synopsis and destroy it plot device by plot device. It’s like taking all my movie reviews and condensing them down into one run-on snark.

And yes, I know that the illustration for the article (seen here) is scientifically inaccurate. I know what you’re thinking; it’s so obvious: no asteroid is actually flying saucer shaped! At least, that’s what they want you to think*.

So go over there, read the article, and leave your own complaints in the comments. I promise I will read them all and take them into consideration.

* Dear readers with an impaired sense of humor: I know that’s not really how the picture is scientifically inaccurate. Of course, the actual mistake is that you should see thousands of stars in the background.

No I won’t.

Related posts:

Blastr: Other than that, Spock, how was the movie?
Blastr: I Was A Zombie For Science
Big budget movies that got their science right
Master of Blastr

MORE ABOUT: asteroids, Blastr, SyFy

Comments (35)

  1. I was actually going to say that the moon is far too close to the Earth if this is to scale. And I really hope that asteroid isn’t to scale either. Yikes!

  2. Steve

    I was going to guess the friction from atmospheric entry was occurring WAY too far out from the planet’s surface!

  3. Josie

    what? there are flaming balls of rock flying around all over the place in near-Earth space. duh.

  4. Mika

    In the blasted article you make this point about blowing up the asteroid:
    “Blowing it up doesn’t change its speed, and you haven’t changed the mass, either: you’ve just spread it out a bit.”

    Do you mean that we couldn’t blow it up to small enough pieces? Or that somehow a huge bunch of really small rocks, that individually would normally burn up in the atmosphere, would somehow still cause a huge amount of damage?

    I mean, what if we “vaporize” the asteroid to gazillion chunks a meter across each, would that still pose a problem?

  5. NAW

    I think one problem that is one big “if”. And it just may, that is still a huge mass heading towards the Earth. This is just purely a guess no real facts behind it. But the last of the rocks may get shielded by the first ones letting the rest hit the surface.

  6. Phil Plait has an asteroid named after him—1654347 Philplait—which is in no danger of ever hitting the Earth, thus foiling his evil plans for world domination.



    I mean, what if we “vaporize” the asteroid to gazillion chunks a meter across each, would that still pose a problem?

    I don’t know. How much would that heat the atmosphere?

  7. Andrew W

    In Deep Impact, didn’t they do what Phil condemns them for not doing? From memory, they split the asteriod, the reaction moved the orbit of the larger chunk enough to miss Earth and only smaller bits hit the planet?

  8. Chief

    Everyone knows that if something was detected with plenty of time to change the event, the people in power will just make motion after motion and continue spending the allocated funds for study after study and then time will run out. This with almost no actual money spent on the direct methods to prevent a disaster.

    Now if it was really saucer shaped…. well now, we would have the correct (ahem) public support behind the effort to deal with it.

  9. julian

    Ok I will be honest, my first thought was
    “Really Skynet??, have we learned nothing from hollywod?”

    my second one:
    ” Phil has an asteroid named after him?, is not that that´s surprising. It´s just: a guy who spends most of his time talking about asteroids hitting or not the earth (yes you do phil) has an asteroid name after him??–> that´s promising ¬¬”*

    *no, I´m not really worried about the asteroid

  10. fagricipni

    My guess is that reducing a large asteroid to dust would save the Earth, but that is definitely wasteful of resources, the methods discussed in the linked article would require much less power and accuracy; after all, once you have blasted it into a bunch of about 10-meter sized pieces, then you have pulverize *every one* of those; the count of pieces that you have to find and accurately target increases every time you pulverize one piece, until finally after repeated multiplication the pieces are small enough to be harmless.

  11. HP

    @Mika, imagine going deer hunting with a gun that shoots a whole bunch of itty-bitty bullets instead of one large one. . . .

  12. Tim G

    The real problem with that illustration is that we don’t see any geosynchronous satellites.

  13. Steve gets it right with the thing being too far out to start glowing from atmospheric friction.

    The artist also didn’t show the shock wave that would be at the front of the thing & there are flames that look like a piece of burning wood instead of a narrow streak. Artistic license has to enter into it there. Gotta make it look like what people think of when they think “flames”…

    Who did the illustration, Phil? Blastr?

  14. Keith Thompson

    I have a question about the gravity tractor idea.

    The probe has to use some kind of thrust to maintain its position, near enough to the asteroid so its gravity affects it, but without crashing into it. Suppose you use low-thrust ion engines to do the job, (perhaps two of them at an angle so the reaction mass doesn’t hit the asteroid and push it when you’re trying to pull it).

    Am I right so far?

    So why not just land the probe on the asteroid and point the engines outward, effectively turning the asteroid-plus-probe into a low-power rocket? Is using gravity more efficient somehow? The asteroid’s spin might be an issue (so land at a pole), but my (probably faulty) intuition tells me that applying the thrust directly will be at least as efficient as applying it indirectly.

  15. shane destefano

    What about this elenin comet supposedly going to be less than 1 AU to earth?

  16. HvP

    Keith Thompson,

    The reason you don’t want to land on the asteroid to push it is due to a number of factors.

    1) It’s much much harder to land on something without crashing than to simply orbit nearby.

    2) There may be debris and irregular surfaces that make it impossible to correctly align the lander (in fact, this is most likely)

    3) It’s harder to remotely communicate with a probe when the radio signal gets blocked by the mass of the meteoroid.

    4) The spin rate and axis of rotation of these types of objects changes frequently and unpredictably. Even the effect of light hitting its surface can cause jets of evaporating material to alter its rotation.

    5) The object might just be a loose collection of dust and rubble without any sufficiently hard surface to push against. If you started pushing a rocket into it you might just end up unintentionally drilling down into a rubble pile.

    All in all, the gravity tug option is much more predictable and less prone to complications.

  17. chris j.

    i personally am impressed that the graphic accurately portrays the north african snowcap.

  18. Laura

    Hey, you forgot to mention Earthstorm in your list of bad movies!

  19. Messier Tidy Upper

    Good article BA, well written. :-)

    I probably shouldn’t mention that one of the professional robotic networks is called SkyNet. Seriously.

    I knew there was one named spaceguard after a reference in Arthur C.Clarke’s Rama series, I didn’t know there was one named after the Terminator franchise. An unfortunate chocie of name. Yikes! 😮

    “In a few weeks’ time, an asteroid hundreds of miles across will hit the Earth, wiping out all life.”
    This part always makes me laugh. Objects hundreds of miles across are bright. .. [SNIP] … more likely we’d find it would pass several times in its orbit before it would hit us. For example, we know of no objects more than a few miles across that can hit us in the next century.

    That’s true enough for asteroids – but, I gather, not so much for comets esp. unpredictable long period comets or one’s on their first pass through the inner solar system.

    So if we cross out asteroid and replace it with *comet* the Hollywood scenario there is plausible if highly unlikely methinks.

    I reckon that would have been worth mentioning – and I’m pretty sure I remember you doing so in your (second) book. :-)

  20. Messier Tidy Upper

    Hmm… Nice illustration but what on Earth has happened to Saturn’s moon Atlas :

    to send it rocketing towards Earth like that? 😉

    When you wrote :

    … no asteroid is actually flying saucer shaped!

    you forgot to note that some moons *are*, BA! 😉

    See :


    Plus given the number of asteroids in our solar system, I think its’ likely that some will turn out to be “Flying Saucer” shaped, we just haven’t encountered any yet. That’s probably a good thing given the conspiracy theorists (eg. likes of Hoagland) and what they’d most likely make of such a find.

  21. Messier Tidy Upper

    “NASA is notified, and they scramble into action. A team of astronauts hurriedly trains, launches in the Space Shuttle, and lands on the rock hours later.”
    Well, let’s just say NASA isn’t exactly nimble.

    You could also have added :

    I) We won’t have the Space Shuttle soon given it stops flying this year. The program is shutting down and it will be very hard – if its possible at all – to restart if its needed.

    II) The Space Shuttle won’t be able to go beyond Low Earth Orbit anyhow (right?)

    III) No, NASA hasn’t got any sceret super-Spaceplanes that like Shuttles but even better conveniently locked away in hanger somewhere ready to fly at a weeks notice.

    Sadly. :-(

    In Armageddon, given the size of the asteroid involved, they’d need a nuke that could detonate with the same energy output as the sun. I’m rather glad we don’t have a weapon like that.

    Actually, pedantic nit-pick mode on (well you did ask for feedback!) that needs qualifying I think – after all nuclear weapons esp. fusion bombs *do* produce the output of the Sun – or a tiny fraction of it or its surface. Right?

    The output of the Sun for how long or how much of it’s surface? That’s an immediate question I wonder about with that.

    I’m also glad we don’t have anything like that – but gladder still that our global enemies lack such weaponry too! 😉

    Such minor nits aside though – great article, BA. :-)

  22. Kaleberg

    Anyone who wants a pretty good, though a bit dated, factual treatment of how we might deal with an asteroid should read Project Icarus, an MIT Press book. I have the second edition, the one that came out after the movie Meteor. It was based on an MIT graduate seminar where they posed the problem to a group of students in various departments: aero & astro, physics, earth & planetary science, nuclear physics. Each chapter was written by a different team and they discuss rocket boosters, nuclear weapons, guidance and control and other issues. Of course, back then, liquid fuel rockets were the standard, so they had the additional problem of the liquid oxygen evaporating during the staging, but that was balanced out because the liquid fueled rocket in question was the Saturn V. The nuclear section does the analysis assuming propulsion by blasting material with a near surface detonation. With all the bogus science fiction versions of the story, it was nice to read a good realistic, point by point analysis.

    P.S. I would have commented on Blastr, but I’ve been too busy doing stuff with my friends to have time to deal with Facebook or Twitter. Where do people find the time for that kind of stuff? You need either a Facebook or Twitter account to post a comment.

  23. NAW

    Speaking of bad space movies concerning the Space Shuttle. Remember Space Camp ( Even when I watched it back in 86, I could see so many things wrong with it. And its unfortunate release date didn’t help it any either.

  24. Ed

    Ugg, this reminds me of my year after taking a film class, I could never just watch a movie and enjoy it, was critiquing everything. Then since I have a computer science job, whenever I see a movie that doesn’t depict the technology right, I cringe. And then all my lawyer friends and family that are cops can’t stand most shows that depict their career.

    So I’ve given up trying to be factual in movies, grab some popcorn, sit back and enjoy.

  25. Nigel Depledge

    Mika (4) said:

    Do you mean that we couldn’t blow it up to small enough pieces? Or that somehow a huge bunch of really small rocks, that individually would normally burn up in the atmosphere, would somehow still cause a huge amount of damage?

    I mean, what if we “vaporize” the asteroid to gazillion chunks a meter across each, would that still pose a problem?

    Yeah, they’d still have the same collective mass and the same speed, so therefore they’d have the same energy. Dumping all that energy into Earth’s atmosphere is possibly worse than concentrating it in one place on the surface (unless that place is in the sea).

  26. Nigel Depledge

    Richard Drumm the astronomy bum (13) said:

    Steve gets it right with the thing being too far out to start glowing from atmospheric friction.

    Wait, what?


    I thought the bulk of the heating when a fast-moving object enters the atmosphere was from compression of the air, not friction. Sure, there’s friction, but that isn’t what causes most of the observed heating.

  27. Gary Ansorge

    24. Ed

    Yes, knowing a lot of science can decrease our ignorant enjoyment of SciFi. On the other hand, the closer a writer gets to the real science, the better the story( no distractions). I especially liked FireFly for that very reason. No need for phasers, blasters of exotic origin, FTL, etc. ,,,and they still use projectile weapons. The one major high tech SciFi gadget they proposed was their “gravity drive”, which I expect was included so they could pull high speed turns w/o turning the crew into jelly. If we ever figure out what gives matter mass, this may actually turn out to be possible.

    Gary 7

  28. jfb

    Mika @ 4:

    For an asteroid of about 10 km in radius (4.188 x 10^12 m^3, which is nowhere near “as big as Texas”) with a density of about 2 g/cm^3 and a closing speed of 5 km/s (which seems reasonable based on what I’ve read), you’re looking at an energy equivalent on the order of 25,000 gigatons of TNT (provided I’ve done the math right, using translational kinetic energy and treating it as a solid, non-rotating body).

    Suppose you manage to blow it into 1-meter chunks. Now instead of one massive object, you have 4.188 x 10^12 objects all hitting at around 5 km/s. You still get roughly the same total energy, although spread out over a wider area. However, I can’t imagine dispersing that much energy over any size area in an environmentally benign manner.

  29. Capt Tommy

    Science be Damned, I liked Armagedon… besides they split the 900 mile dia meteor and the parts passsed on either side of the earth. and that, though far fetched, “could work” (the Earth looked close because, those scenes were shot with a telephoto lens for dramatic affect).

    Obviously You were groaning too much to actually see the end.

    Though using the moon gavity well to sling shot around and pick up speed? Everyone knows, that would send them back in time to 1968, where they could contact the USS. Enterprise, so Kirk could save the day.

  30. Capt Tommy

    Science be damned Two:

    In Deep Impact, the idea was to shatter the ICE BALL (Comet) and the small bits (notice the scene) would melt as they entered the atmosphere. Logical assumption Ice+Speed+Atmosphere=Melt, Of course they forgot about +Heat, which would probably cooked most of Canada and melt the Greenland icecap But that is another movie….

  31. In Phil’s Blastr article, he states:

    “It would take something about the size of a football field to do us any real damage (and even then it would be local, not global)”

    This analogy runs into the same problem that _Armageddon_ did when they said the asteroid was “the size of Texas”.

    How THICK is a football field?

    If we assume a football field is 100 yards long and 160 feet wide, but that it’s only 1 inch thick (about the height of the grass or astroturf on its surface), that’s only 4000 cubic feet. That’s not a very large object at ALL!

  32. #15 Shane Destefano:
    What about it???
    An AU ( astronomical unit ) is the mean distance of the Earth from the Sun, roughly 93 million miles. So if we say a comet is going to pass less than one AU from Earth, it means it’s going to pass closer to us than the distance of the Sun. Big deal!!!
    That means it will hopefully be quite an impressive sight for astronomers – but not exactly anything to worry about. DUH!!!

  33. Phil Giannotti

    Actually, Elenin will pass approximately .23 AU from Earth (according to JPL’s info as of 3/25/11)…. The moon is .0026 from the Earth, so unless there are erroneous calculations or Elenin goes way off course somehow, I think we’re clear.

    If it does show up in the sky, I’m sure there will be tons of people assuring us that it’s the Star Wormwood and we’re all doomed. Comets are good like that.

  34. Christopher F.

    Mika @ 4:

    I used to think that exact same question myself. “If we could blow the asteroid into small enough chunks to just burn up in the atmosphere so nothing could hit the ground, wouldn’t that be good enough?”

    As others (including Phil himself) have said, the total energy doesn’t change. The problem is that all that stuff burning up in the atmosphere at once is going to dump a *LOT* of heat all across the globe at once. It would be like placing the Earth in a huge blast furnace as the atmosphere superheated to hundreds and hundreds of degrees. It would be a global firestorm.

  35. julie dills

    i have been looking for an idea for my next tattoo and now i have left arm has a space theme with the moon,a rocket,stars and a few planets..i’ve been thinking on what would be cool to go along with my other space tats and what could be better than an asteroid streaking towards earth.the earth will be on my elbow(ouch) with the asteroid and flames streak down the side of my forearm to my wrist.sweet!many thanks!


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