I believe that’s the same for every planet. And every moon. For every orbit.
Its just that the barycenter is inside the more massive object when one is much more massive than the other. Not that this makes much of a difference to anything.
Correct.
I also believe that on of the criteria for a binary planet is that the barycenter is outside either body. Like Pluto/Charon.
depends! do you wanna know how the system will evolve over long periods of time?
… then yes!
no material object orbits another material object and they instead orbit their collective center of mass somewhere in space.
That’s exactly what happens. Why do you think this is incorrect?
It seems to fundamentally change what it means “to orbit” something.
As I understood the term, orbiting would be used correctly in these cases:
A lighter object orbits a heavier object, and both of their paths of motion are elliptical about their barycenter
Two objects of identical mass orbit each other, and their paths of motion are circular about their barycenter
In contrast, the image above implies the following:
A lighter object does not orbit a heavier object; they both orbit their barycenter with an elliptical path of motion
Two objects of identical mass do no orbit each other; they both orbit their barycenter with an circular path of motion
Even the Wikipedia page for barycenter, which OP linked to, opens with the following:
“the barycenter… is the center of massof two or more bodies that orbit one another and is the point about which the bodies orbit.”
Perhaps “orbit” as a verb has two meanings, depending on the specificity of the context.
Just because a more accurate description exists, doesn’t mean that the less accurate description is fundamentally wrong. Depending on context, the less accurate description may be perfectly suitable for the subject at hand. If your priority is to be the most correct, then by all means go ahead and use the more accurate description.
I think this logic applies to a lot of things.
I guess your conclusion is right. In situations where the barycenter of two (or more) objects is not sufficiently different from the center of mass of the heaviest object, we simplify the description by assuming that the barycenter and the center of mass of the heavier object are equal.
Just because I’ve already edited it, here’s an animation of Earth orbiting the Earth–Moon barycenter:
When I was a kid, we were taught there’s 9 and only 9 planets, they all orbit the sun, and humans have existed for at least 30 years.
Now I find out 1 of those 9 planets was a fraud. Theres also thousands of OTHER planets outside our solar system. And also, time is an illusion only placed in our reality to distract us from the concept of a realized immortality. We die when we want. We come into this world naked, bloody, covered in goo, and getting spanked until we cry. And we die the same way…when we WANT to!
School is all a bunch of lies man! Trust your instincts! Consume prilosec!
humans have existed for at least 30 years.
True
In a field of study where it’s not just acceptable, but prudent to round pi to “1” because the numbers are that big….
I gotta say, it’s close enough to say Jupiter orbits Sol. Just saying.
this disgruntled me as a biochem grad and we think the periodic table is
H C N O P S Na Mg Cl K Ca Mn Fe Co Cu Zn Se Mo I F
Nah, there is no way any astronomer studying orbital mechanics in our solar system is rounding pi to 1. There is virtually no practical calculation you could do on the mechanics of the sun or planets where rounding a known constant by a factor of 3 would yield any useful result whatsoever.
Rounding pi to 1 only makes sense when the uncertainty in the numbers is large, not the magnitude of the numbers, and we know the masses and distances of the objects in our solar system to an amazing level of precision!
Plus, the fact that Jupiter is massive enough to actually exert an influence that large on the sun is pretty fucking cool!
The reason being, that once you go large enough, a multiplier of three is irrelevant, and they only really care about orders of magnitude. You might be tempted to argue that that doesn’t happen inside the solar system, and you’d be right. Mostly.
Except that astronomy doesn’t concern itself with just our system. So yes. Astronomers do frequently round to 1 because it really doesn’t matter that much in the scheme of things. (particularly talking about distances.) it’s even more so for cosmology.
Sure, I totally agree that when you’re dealing many with orders of magnitude, the factor of 3 is dwarved by the other uncertainties.
But we’re talking about our solar system, and specifically the orbital mechanics of our planets and sun, where the quantities and scales only span a couple orders of magnitude in total. A factor of 3 absolutely makes a difference. That’s the difference between the orbit of Mercury and the orbit of Earth.
Then there’s the practical point that, regardless of scale, rounding a known constant by that much makes no sense at all, unless you’re trying to estimate huge numbers in your head. If you’re using even the simplest of calculator, estimating pi as 1 is a deliberate choice to reduce accuracy.
Not when that definition of pi goes to all 300 trillion decimals that we have resolved. (To be fair, I don’t know of any that do… but eh…yeah. And I’m pretty sure it was defined by a masochist if one did.)
That leads to unnecessary time spent calculating even simple equations. That level of precision is almost never actually needed.
With fermi problems, usually that level of precision is moot and potentially a waste of time. (Particularly when the math is requiring some kind network cluster to do.)
Sure.
But sometimes, the problems are complex enough that solve time becomes a concern. When they’re complex enough, you start asking “is everything these precise enough to justify that” and when the answer is “no”, then you don’t do that because runtime on networked clusters like AWS costs money.
And when you’re talking about scales that encompass the galaxy…. Well. There’s just not a lot of precision there to begin with.
…. Are you reading what I’m saying?
Yes. For simple, common problems. You are correct.
But sometimes they’re not running simple problems. Sometimes, the run time on servers costs money. Sometimes, there’s no value to be gained by being any more accurate- and it increases those costs.
Now, in those times…. Are you really going to tell me that costing your organization more money without any useful gains…. Is “way more professional”?
Also? Don’t get me wrong, that threshold is getting and higher every year. I have more computing power in my cell phone than they used to put a man on the moon.
None of that changes that astronomers sometimes use 1 instead of pi, and that the barycenter of Jupiter-sun orbit is close enough to say Jupiter orbits the sun.
fermi approximations happen all the time in astronomy. The numbers are frequently so large that the only meaningful quality is how many orders of magnitude it has.
More to the point, using pi makes calculating things much harder. For example, we don’t really need a precise distance for most things; so using “3” makes the calculation unnecessarily spend time in computation.
It’s like the old joke, “what’s the difference between a millionaire and a billionaire?” (“About a billion.”)
The barycenter is sometimes outside the diameter of the sun. Not always, and I believe not even usually.
Yes, today I’m being that guy. Still a cool factoid.
Well, while we are being ‘that guy’, factoid is one of those words which has changed its meaning by being used wrongly for so long that the original meaning has all but vanished.
A factoid is technically supposed to be something resembling fact, but not actual fact. (The Greek suffix ‘-oid’ normally being used for that purpose, like in paranoid, “like knowledge” or asteroid, “like a star”).
The best thing about factoid, is that factoid is now a factoid. Because it resembles what it is not lol…
Anyway, nowadays, you are allowed to use it the way you did, at least in the descriptivist world view. The prescriptivists may disagree, however. And those people are often ‘that guy’ ;)
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