Speculative Science Question
As I was driving home from work (wife needed the car today) I was asking myself a science question, and didn’t have an answer. So, I figured I would throw it out to you chuckleheads, and see who has the biggest Physics brain.
What would the change be here on Terra Firma if the moon were in geostationary orbit instead of revolving the way it does now? (Assume that it is located at the same distance, but always present over South America.)
Obviously we would have no tides. But other than that, what? Would we be even more oblate that we are? The poles would still be somewhat flattened obviously, but would the earth be more egg shaped owing to the gravitational pull being a constant? What effect on tectonic movement? And while you are at it, do you think it would have changed history at all? I can’t help but wonder if man wouldn’t have set out West from Europe earlier to see why the moon was located there?
These are the questions that plague me, and I’ve noted in the past that we have some “big brains on Brad” so, any answer would be appreciated.
Category: Politics
You just had to go and do that, didn’t you, TSO? Ask questions impossible to answer without consulting a science geek. Oh, dear me.
I think it would set up an interesting orbital effect…the earth and moon would have an eccentric orbit, like the effect of the off-center axis of the teacups at a parking lot fair.
I swear I wasn’t trolling. I saw the moon on the way home, and got tired of listening to Tebow Radio, so I started thinking about this question.
Besides not having tides, the sun would be ever present in the sky above South America, that clearly would have sociological/religious ramifications in regards to that continents development.
Also, parts of Europe and Asia wouldn’t even know the moon existed.
I’ll have more when I can get home and do some math.
It’s the malaria meds. Right? You’re still having side affects from them. Right?
I believe oblation is caused mainly by the rotation of the earth. I also believe the suns gravitational effect is far greater than the moons and because of that, we would still have tides. That being said, I wonder how much tectonic movement would be effected….I was once upon a time a physics teacher but I skipped geophysics…
I wasn’t even thinking that the moon would have to be much closer than it tis no for that to happen or we would have to have almost a month long day….that changes things….
it is now…
I only have one concern, would it in any way disrupt my home beer brewing process. Other than that I don’t care!
You really shouldn’t drink and drive. Or drink and THINK, for that matter.
And out of curiosity, does any planet that we know of have a moon in geostationary orbit?
It would have no effect on tectonic plate shifting as that is all produced here on earth.
As for the rest of it, it is difficult to say without more information to plug into the scenario. If it was stuck over South America, then the polar ice caps would be shifted due to earth’s tilt being greater than 23.5% (or whatever it is now) assuming the magnetic poles stayed the same. The arctic circle would cover Canada and probably some of the U.S., depending on how far south the moon would be relevant to where it is right now. Right now, the moon is tidally locked with the earth (meaning one side always faces us). Since the moon is about 1/6th the earth’s mass, for both sides to be tidally locked like that, it would have to be a lot closer and both bodies would orbit each other at a much more rapid pace…somewhat like an adult holding hands with a small child and spinning each other around in circles. The days would become much shorter and the sun would not arch across the sky smoothly as it does now, although I don’t know exactly what the degree of change would be.
I would think that would have quite a negative effect on most things here on earth, as they are right now. However, if this had been the situation from the beginning, it is possible that life would not have ever developed here on earth or, if it did, it would probably be radically different than it is now
#4 the sun wouldn’t be stuck over South America. That would mean that neither body was moving relative to each other and gravity would take over and ruin our day quickly
speaking of hobbies (#9) TSO needs one in a big way.
May I have a hall pass to use the latrine Mr. TSO?
OT the moon’s gravity field affects the tides far more than does the sun’s. That doesn’t mean that the sun doesn’t affect the tides at all, just that it’s effect would be far weaker
TSO, the ironic thing is that the moon’s velocity is slightly too fast for the gravitational pull that the earth exerts upon it. As a result, it moves away from us about 1/4″ every year. At that rate, in about 250 million years, we’re gonna lose it and then we’re really screwed
Well, full disclosure, my degree was in history and I only took a single semester of astronomy, but IIRC the orbital speed of on object around the earth is determined by its distance from the center of the earth. At each distance there is a specific “goldilocks” velocity (<— NOT a scientific term) that is not too fast (which would make it slingshot away from Earth) and not too slow (which would make it decay and eventually fall to the earth's surface.)
Furthermore (again recalling that fuzzy memory), that is the reason for the 22,500 mile altitude of geostationary satellites – because that is the altitude at which an object will travel at such a speed that it remains above a specific point on the earth.
IOW, in order for the moon to be stationary, it would have to be a 1/10th of its distance from earth now, I can't even imagine what kind of effect that would have on Earth, given that the moon is by far the biggest moon in the solar system when compared to its "parent" planet (Mars, for example, is a little smaller than earth and has two moons, and I don't think either of them is bigger than 10 miles in diameter, though I'm too lazy to google and find out.)
17…the altitude alone doesn’t matter for the artificial satellites. What matters is the velocity in relation to the object being orbited. The closer an object is, the faster its velocity must be to prevent it being overwhelmed by gravity and crashing. If those satellites were further away, they could travel at a lower velocity
@17, that was the basic answer this guy had as well:
http://scitalk.wordpress.com/2008/03/13/what-if-our-moon-was-in-geostationary-orbit/
But I always thought as @18 did. I couldn’t figure out why that distance was the accurate one, and I actually still don’t. If we assume it does it’s circumnavigation in 24 hours, I would have thought that the distance would be irrelevant. Obviously I am wrong, but I’m not sure exactly why I am wrong.
Why hasn’t Michiu Kaku chimed in yet? Doesn’t he read us?
It would never happen anyway. The alien bases on the far side of the moon would have been compromised LONG ago and we NEVER would have been able to fake the Apollo missions from that soundstage in the desert southwest so yeah, there would have been ramifications.
/{;-D ready, go.
You’re also not thinking about the gravitational pull of the moon itself which, while not as strong as the earth’s, is not insignificant either. That would allow for a much higher geo-stational orbit than our man-made satellites. I think the 22,000 mile mark is an optimal distance for man-made satellites but I’ve never looked it up as it’s never interested me.
I am right about the velocity in relation to the distance providing a stable orbit. You can see it in our own solar system. Mercury, much closer than earth to the sun has to revolve at a much faster velocity (about 106,950 MPH) to avoid succumbing to the sun’s gravity. As you get further away from the sun, the velocities slow proportionately to the sun’s and the solar body’s mass. For example, the earth revolves at about 66,600 MPH; Mars’ velocity is about 53,600 MPH
Obligatory…..
( http://cdn2.holytaco.com/wp-content/uploads/blog/fe/9143/Nerds-Gallery.jpg )
NERDS!!!!!!! (lol)
We would have solar eclipses and lunar eclipses in exactly the same place every day and night, and never anywhere near Chicago…probably closer to Cairo, which means I’d have to drive down there to see them. Or move there. And the Mississippi River would probably flow backwards, and there would no longer be the tidal bore in the Bay of Fundy.
PH, that was another thing that occurred to me, and the trick that (Pizzaro?) pulled with predicting the Eclipse wouldn’t have worked, thus Spain never colonizes there, and Mexicans speak…..Klingon?
I must have made that last thing up, but I thought someone avoided an untimely fate at the hands of Mayans by predicting one.
TSO, I like where you’re going with the Klingon comment
Klingon! Yes!
Chip! Warn people!!!!!
I like that there was finally a post where I could really add something to the discussion. I’ll check in on it later…have to get back to my calculus homework
In truth there’s no gravity…there are so many people who suck, that it keeps the water and everybody on the the earth
The answer, really, is quite simple. If the moon were in geostationary orbit over South America, we would be here wondering what it would be like if the moon actually orbited the Earth and wasn’t a fixed point in the sky.
The moon and earth would pull themselves together due to gravity, and we’d all die. The end.
TSO
Christopher Columbus was able to get the natives on an island he was stranded on to bring him food by predicting one. He was an incredible astronomer….
Then my wife would have her period every day of the week. Holy crap…
@34
Bwahaha!!!
@ 17 WHAT? Will my home beer brewing operation remain intact? And if not what can I do now? When is this going to happen? Sh*t … this ruins everything!
#17 martinjmpr is on the ball. The physical effects of TSOs thought experiments would be astounding. You will have significant tidal effects (both oceanic and tectonic) since the “power” of the moon varies by the inverse square of it’s distance from the Earth. Since a geosynchonous orbit must be ~35km from the surface (1/10 current orbital radius), the force exerted by the moon would be almost 100 times greater than current. Assuming that the geosync moon would have at least some orbital inclination, the actual track of the moon would be that of an analemma (figure eight), so 1) our tides would be daily “wiggles” of tides instead of smooth lunar-month cycles, and 2) the tectonics under the ground track of the earth would be relatively “busier” than elsewhere in the world.
Orbital dynamics for us would be completely turned upside down, since we know would have huge third body in play. Geosynch orbits for man made satellites would be largely impossible at least within the same semi-sphere as the geosynch moon. Other, non-synchronous orbits would end up being highly eccentric and full of odd perturbations.
There would also be many many more eclipses observable, at least on one side of the world.
TSO,
thanks for the diversion, I needed a physics fix.
@ 37 Thanks for clearing it up for me!
Considering that the earth and moon were much closer to each other 4 billion years ago, the earth would have to spin faster, thereby ruining Master Chief’s homebrew beer, my wine and cheese & pepperoni pizza collection, and my cat Sparkle Pants’ naptimes.
partially correct answers above; to maintain a geosynchronous orbit you need orbital velocity which just overcomes the mutual gravitational pull of the Earth and Moon combined, at the distance between them where the various vectors canel out. It’s not just speed vs. altitude, but those are factors. It’s balancing how fast the Moon is going around the Earth (which is still rotating) to stay exactly above it from the altitude where the gravitational pull is matched. Sorry, been 40 years since a physics course and I’ve killed a lot of brain cells since then.
Master Chief,
Just to be 100% clear, and I have a vested interest here: malting, mashing, fermentation, and other biochemical processes would be unaffected by the lunar changes. 😉
v/r
The Senior Thief
The main beneficiaries would be Brazilian and Argentine werewolves-duh!
It would have to be about 22,000 mile up to have a geosynchronous orbit, alot closer than the current 240,000 +-miles. So what you are proposing (Assume that it is located at the same distance) is impossible.
Chris H: I believe you’re assuming an absence of mutual tidal locking. If mutual tidal lock occurred, things should end up perfectly stable and net daily tidal variation would drop to only that caused by the sun – or about 3% of today’s net tidal effects. Tidal stresses due to the moon’s gravity would still be there, but they’d now be static stresses vice changing on a daily cycle.
Could possibly have some nasty effects on fault lines over the millennia as continental drift occurred and those stresses slowly reoriented themselves, perhaps. If drift isn’t caused by the estimated 90+% of tidal energy which is thought to be dissipated as heat today, of course.
Joe: I believe TSO is assuming the moon would move to the distance necessary to achieve geostationary orbit – e.g., over the equator, aligned with same, orbiting in the same direction as the earth’s rotation, and was at the appropriate two-body orbital distance to achieve exactly 24-hour orbit.
@37 – Chris – ‘highly eccentric and full of odd perturbations’?
That sounds like some of the people I’ve run into at the Renaissance Faire.
Hondo, mutual tidal locking only occurs when the two objects are similar in mass. I’m not sure of the lower limit, but the moon is about 1.2% of the mass of the earth and may not have enough mass to create a mutually locked situation. The Pluto/Charon link, our only local example of mutual tidal locking, is a result of Charon being 11% of the mass of Pluto.
Regardless, the broader point of tidal locking does apply here, but most of the changes will only be detectable in geological time frames.
Whether the tidal stresses are static or not depends on the inclination of the new orbit of the moon; the more inclination on the orbit (creating the analemma shaped ground track) the more “stir” or dynamic effect the moon’s net force will have on Earth’s tidal systems.
Re: your response to Joe. The assumption about distance is critical to the idea; I believe that the orbital velocity to achieve geosynchronous orbit at 240,000 miles would far exceed the escape velocity of Earth.
…lovin’ the full on geek fest today.
@46 Ex-PH2: Eccentric and perturbed also describes a lot of us…and I consider it a compliment.
Chris H: TSO specified a geostationary orbit, not geosynchronous. That implies an equatorial orbit with zero inclination and orbital motion in same direction as primary rotation. I believe that would cause effective lock of primary with secondary (from secondary’s perspective). We already have tidal lock of the secondary (the moon) with the primary from the primary’s (earth’s) perspective.
On reconsideration, however, maintaining infinite stability would likely be impossible, even if mutual tidal lock were temporarily achieved. Even if it’s only 3% of today’s total, the sun’s tidal effects would eventually cause the earth to slow down a touch due to oceanic tidal friction. It would initially take much longer than it does today, but it would still happen. This would disrupt the synchronization between rotation, orbital period, and tidal forces. Eventually the moon would speed up a bit (conservation of total angular momentum), move away from the earth – and in relatively short order (in geological terms) start causing some truly massive tidal effects on earth reinforcing those of the sun. ON earth, things would eventually get very ugly.
From my journal on 3/13/11 — I did not realize that the Earth’s axis had acutally shifted 3.3 inches with the 2/27/2010 Chilean quake. I missed that broadcast. It doesn’t sound like much of a shift, but the recessional tilt is what gives us our seasonal changes.
Now I wonder if there is a submarine quake involved when whales beach themselves, and not just disease.
– Alan Boyle, editor of Cosmiclog, writes that the actual shift of the earth’s axis is 6.5 inches, updated from 3.3 inches with fresh data. Also, the subduction that occurred during this quake moved Japan 8 to 13.5 feet eastward.
On Kushu Island, the Shinmoedake volcano has erupted, but a connection to the major quake and aftershocks has not been discussed so far.
I’m wondering if this axial shift is going to have a “butterfly effect” on future weather systems.
The total shift of the earth’s axis from the 2004 Sumatra, 2010 Chilean and 2011 Japan quake was 9.9 inches. Those three quakes took a few microseconds, about 4.2 total, off the rotation of the Earth, making the days a small but measurable shorter length. So if the moon, which got the earth spinning on a 21-hour day back in the beginning of time, were to go into a geostationary orbit, it might have a noticeable effect on the length of days and nights, thus interfering with MCPO NYC’s home brewmaster status.