This blog is late to the game in commenting on the physics of the Hollywood film Moonfall — but does that really matter? Geophysics research and glacially slow progress seem synonymous at this point. In social media, unless one jumps on the event of the day within an hour, it’s considered forgotten. However, difficult problems aren’t unraveled quickly, and that’s what he have when we consider the Moon’s influence on the Earth’s geophysics. Yes, tides are easy to understand, but any other impact of the Moon is considered warily, perhaps over the course of decades, not as part of the daily news & entertainment cycle.
My premise: The movie Moonfall is a more pure climate-science-fiction film than Don’t Look Up. Discuss.
Moonfall gets some stuff right. As the Moon starts getting closer to the Earth, the increased gravitational pull starts creating huge tides (and extreme thermocline tilt, implying super El Ninos), while simultaneously sucking the oxygen at upper altitudes. These behaviors are described in various articles found on the web that are fact-checking the film’s physics
The majority of people watching the movie will ignore everything about the science but there may be a few youngsters or others that gain some insight and perhaps apply that to a future Earth sciences model. It was Arthur C. Clarke that imagined the “Spaceguard” in one of his Sci-Fi novels that eventually become reality as an early-warning system for asteroids, see the Spaceguard Foundation. It also serves as a plot device of Don’t Look Up. What will come out of Moonfall? Who knows? NASA has recently reminded us that the moon will exaggerate climate change sea rise through tidal surges every 18 years, see
So, ignoring the over-the-top human aspect of Moonfall, consider only the geophysics that it brings up. Current geophysics ignores the idea that the moon’s long-period orbit is already violently sloshing the Pacific ocean’s equatorial thermocline, creating cycles of El Nino and La Nina. It’s an overlooked feature of a thermocline that it exists within a reduced gravity environment, whereby there are small differences in density above and below the thermocline.
Relating to Moonfall, a reduced gravity environment is equivalent to having the moon’s orbit swing much closer to the earth’s surface than it physically does. This doesn’t do anything special to surface (barotropic) tides since the interface is not a subtle density difference, but the subsurface thermocline can shift hundreds of meters vertically due to lunar gravitational forces (the prevailing “consensus” opinion is that the wind causes the shift).
The analytical issue is that solving a sloshing problem in hydrodynamics takes some doing, and the fact that El Nino/La Nina cycles are erratic means that the connection to tidal cycles is difficult to extract. No humans in the loop on this problem, just pure geophysical fluid dynamics. We have it all figured out here, including the Moon’s impact on the QBO and on the Chandler wobble, but considering how slow consensus Earth sciences progresses, we have to be patient.