2561: Moonfall

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Novel ideas and cool explosions are both good, but what I really want from a movie is novel ideas ABOUT cool explosions.
Title text: Novel ideas and cool explosions are both good, but what I really want from a movie is novel ideas ABOUT cool explosions.


Megan asks Cueball if he is excited for the release of the movie Moonfall.

Moonfall was released in February 2022, a couple of months after this comic. Its director, Roland Emmerich, is known for blowing up things in his movies (see for instance the Roland Emmerich Supercut), as well as for factual inaccuracies in his work (mainly the scientific implausibility of his many disaster movies like Independence Day, The Day After Tomorrow and 2012).

The basic premise of Moonfall is that a mysterious force manages to knock the moon out of its orbit, leaving it on a collision course with the Earth. This is scientifically preposterous (see analysis below), making it potentially 'cringe-worthy' for someone who prefers hard science fiction where things are more grounded in established scientific facts and theories. Cueball states that a story based on good science can potentially serve as a novel window into what the real world may look like someday—or, as he puts it, "expand our ideas of what's possible."

But Cueball then goes on to imply that he's still looking forward to the movie because his less critical side is still excited by things like cool spaceship noises and smashing moons into things. Sometimes you just want to get lost in mindless action, even if it's less 'mature' than a well-thought-out meaningful plot. Megan then sums things up by playing off Cueball's wording from the previous panel, saying she's excited to "expand our ideas on how much stuff can explode at once." Given the scale of Moonfall's premise involving a potential planetary-scale collision, as well as the director's tendency to use gratuitous visual effects and explosions in his movies, it seems reasonable to conclude that the movie will likely contain quite a lot of stuff exploding at once.

In the title text Cueball continues by explaining that while novel ideas and cool explosions are good, what he really wants from a movie is novel ideas about cool explosions. So new ways to explode things, or ideas about exploding more things at once. Or both!

1536: The Martian contains a similar discussion of an (at the time) upcoming movie, in particular The Martian. In that case, however, the subject of the comic was the movie's high scientific accuracy and lack of huge explosions, rather than the other way around.

Realistic analysis of the scenario[edit]

For the moon to fall from the sky, it would have to stop orbiting. Most forces applied it to will simply change the way in which it is orbiting, making the orbit more elliptical, larger or smaller. To stop it from orbiting entirely, a 'braking' force would need to be applied in the opposite direction of its travel, to halt it.

The moon's mass is about 7.34767×1022 kg and its speed about 1.022 km/s, so the energy needed to stop it is ½mv2 or about 3.8364×1028 joules. That's about the energy of 1 trillion large nuclear explosions, centered on the leading-most point of the moon's surface. A precisely-oriented stellar body could strike the moon to do this, like a billiard ball colliding with tons of interstellar moon shrapnel instead of dust.

Less counteractive energy could make the Moon change orbit to one with a perigee below the surface of the Earth, close enough to (partially) enter the atmosphere or merely bring it down beneath the applicable Roche limit. These scenarios would be only technically less catastrophic, and whether the Moon fragments from the initially applied force, the stresses of its nearest (non-contact) distance to Earth or actually survives largely intact until there is a more direct physical interaction, the precise degree of the effect might be practically academic.


[Cueball and Megan walking to the right]
Megan: Are you excited for Moonfall?
Megan: Or cringing?
Cueball: Well...
[Closeup on Cueball]
Cueball: I like when stories are grounded in good science because it's exciting to expand our ideas of what's possible.
[Zoomed back out to Cueball and Megan walking to the right. Cueball has his palms raised]
Cueball: But I also support giving Roland Emmerich as much money as he wants to make cool spaceship noises and smash moons into things.
Megan: Excited to expand our ideas of how much stuff can explode at once.

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Well, it did fund 8 out of 10 seasons of MythbustersSeebert (talk) 19:11, 29 December 2021 (UTC)

What is "it"? Barmar (talk) 21:58, 29 December 2021 (UTC)
Explosions, probably. -- Hkmaly (talk) 23:15, 29 December 2021 (UTC)
Yes, 'novel ideas ABOUT cool explosions' (alt text) Seebert (talk) 14:58, 30 December 2021 (UTC)

This synopsis makes me eager to never ever see this tripe, which the comic failed to achieve. Thank you, explainxkcd, for saving me time and money. 20:03, 29 December 2021 (UTC)

It doesn't sound much different from most other action blockbusters, like the "Terminator" franchise, or "Armageddon". And it will probably be better than the "Transformer" movies. As Cueball and Megan indicate, it's mostly about watching lots of things blow up, not about plausibility. Barmar (talk) 21:57, 29 December 2021 (UTC)
”…only to find out that our Moon is not what we think it is.” – Wait, what, the moon isn’t cheese?? -- 22:32, 29 December 2021 (UTC)

Only thing less likely than Moon suddenly getting on collision course is that we will be able to prevent the collision. Wait. I see he lowered the bar even more with only THREE people somehow fixing it without help of rest of NASA ... how do they even get to space without help? -- Hkmaly (talk) 23:14, 29 December 2021 (UTC)

"[O]ne astronaut from her past, Brian Harper and a conspiracy theorist K.C. Houseman" is grammatically confusing. That could be either three people (assuming it's an omitted Oxford comma) or one person (an astronaut named Brian Harper who spreads conspiracy theories under the pseudonym "K.C. Houseman"). It needs at least one more comma if "Brian Harper" is supposed to be an appositive 06:06, 30 December 2021 (UTC)
I believe it's a quote. So the grammatical errors are on the movie producers. ---- (talk) (please sign your comments with ~~~~)
On Wikipedia, now linked from the Moonfall link, it states two astronauts and a conspiracy person --Kynde (talk) 12:42, 30 December 2021 (UTC)
This point is utterly irrelevant to this comic!

To be fair, Shakespeare not writing Shakespeare is NOT the idea of Emmerich, and the idea was so seriously discussed that it has a Wiki page: https://en.wikipedia.org/wiki/Shakespeare_authorship_question 09:34, 30 December 2021 (UTC)

Agree I have deleted this and just mentioned three of his most catastrophic films. --Kynde (talk) 12:42, 30 December 2021 (UTC)
Plenty of Emmerich's listed disaster films use stupid ideas other people thought of—he's hardly the first person to have said 2012 would be the End Of the World. But fair enough; I just thought it was an amusing aside. GreatWyrmGold (talk) 20:41, 31 December 2021 (UTC)

I think Ronald is an amateur :-D. The Danish director Lars von Trier managed, in Melancholia to let the Earth hit into a planet large enough that Earth could have been it's moon. Of course his budget was rater smaller so the explosions are not so cool. But the damage was total obliteration, and no rescue team, hence the title matches the film --Kynde (talk) 12:42, 30 December 2021 (UTC)

There was also When Worlds Collide (1951 film) (imagine what Ronald/Bay would have done, with the full power DreamWorks rendering, or similar). Though (as everyone knows) when the Moon leaves orbit it goes away from the Earth at a strangely plot-friendly velocity that lets them both pass many extrastellar worlds (roughly one a week!) and yet still visit and return from them a convenient number of times while they are somehow still in range of their limited spacecraft... 15:33, 30 December 2021 (UTC)

This sounds a bit like the plot of Majora's Mask. --WhiteDragon (talk) 13:50, 30 December 2021 (UTC)

For some reason 2562 is not on here; i thought a bot automatically added new xkcd posts but for some reason 2562 wasn't added and its been a few hours 17:00, 31 December 2021 (UTC)

Moonfall sounds like it should be the sequel to Skyfall. These Are Not The Comments You Are Looking For (talk) 02:50, 2 January 2022 (UTC)

Why does the mass of the moon have two leading 0, but is in scientific notation. Shouldn't it just be ^22 instead of ^24

Fixed! Dansiman (talk) 22:33, 21 January 2022 (UTC)

Call me someone living under a rock (hopefully not a Moon-sized one, descending at great speed) but, in seeing the edit to rephrase the release as a thing now happened, I just realised that I've seen practicaly no advertising or reviews for this film. This comic is basically the entirety of the information I have seen about this film even existing, except for a half-glimpsed trailer back in January when I glanced up from the book I was reading, during a TV ad-break, and realised that the current fuss (between the usual commercial nonsense) was a typically abbreviated trailer, and almost immediately ended, never to be seen again. I presume it is (or was) on at the local multiscreen, but they no longer post their weekly schedules up like they used to, so even when I pass the entrance I remain uninformed. (Is it as good as we expected? Or 'as good'?) 18:48, 28 February 2022 (UTC)