Planet term I am unfamiliar with. Non-locked body?

varonica

varonica
DanielKT said:
that seems completely counter intuitive to call it a non-locked body xD
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There's a field in the database that identifies whether a body is locked or not, they could have used some other term I suppose, what do you suggest that's better than the one that actually says what it is, a non-locked body?
 

Factabulous

Factabulous
Not sure what the OP is talking about - that edsm page doesn't talk about 'not locked', and neither does the game that I've seen. When it talks about tidal locks it is pretty clear 🤷‍♀️

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Sapyx

Sapyx
I assume the OP has derived the term from a third-party tool. Since they're out exploring, I would presume it's Elite Observatory. According to the Elite Observatory thread, one of the default "interesting things" you get notified about is a planet with "Fast and non-locked rotation".

Planets with fast rotation are considered "cool to visit" places, because you can get some interesting sunrises and sunsets from the surface. However, planets or moons that have tiny, fast orbits are very often tidally locked to the thing they're orbiting, and that means they rotate fast too. Tidally locked worlds are less cool, photographically, because it means the giant object in the sky that they're orbiting very close to doesn't actually move in the sky, it just hangs there in the same place forever - which is less cool than a rise-set cycle that only takes a few hours, or less.

In this case, we have a gas giant that rotates in 0.3 days (about 7.2 hours). Gas giants that rotate quickly aren't interesting in terms of landability, but they are interesting for another reason: they are often "oblate" (flattened spheres), and the oblateness of planets (but not stars) is modelled in ED. Out in the real universe, Jupiter rotates in just under 10 hours, and Jupiter is noticeably non-spherical both in real life and in ED. The screenshot from EDSM doesn't show it, because EDSM uses generic pics and not actual pics of the planet in question, but if you flew up close to Dryooe Flyou SI-J d9-448 4, you should certainly notice that it wasn't quite round.

Oblate gas giants aren't really impressive, since many gas giants have short enough rotation periods to cause visible oblateness. Oblate solid planets are much harder to find, and more visually striking.
 

varonica

varonica
Factabulous said:
Not sure what the OP is talking about - that edsm page doesn't talk about 'not locked', and neither does the game that I've seen. When it talks about tidal locks it is pretty clear 🤷‍♀️

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Sapyx said:
I assume the OP has derived the term from a third-party tool. Since they're out exploring, I would presume it's Elite Observatory. According to the Elite Observatory thread, one of the default "interesting things" you get notified about is a planet with "Fast and non-locked rotation".
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Yeah Elite Observatory does that, flags a body not tidally locked with a fast rotation as a "non-locked body with fast rotation", it's simply how they decided to pass the data from the program to refer to the phenomena of a fast rotating non-tidally locked body that players might want to visit, there are a million ways you could write it out to pass that info to people, but that's the way they chose to write it out in the field for display without chewing up to much space in the reference database. It's a non-issue.
 

Eahlstan

E
Sapyx said:
Tidally locked worlds are less cool, photographically, because it means the giant object in the sky that they're orbiting very close to doesn't actually move in the sky, it just hangs there in the same place forever - which is less cool than a rise-set cycle that only takes a few hours, or less.
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Common misconception. "Tidal locking" and "synchronous rotation" are not synonyms.
As this comes up all the time I asked Orvidius to make a spreadsheet of tidal locked bodies that aren't in synchronous rotation a long time ago (as an in game proof, but it's not the same in reality too). There are so many that he had to limit it to bodies with a difference greater than 50% between rotational and orbital period. To date it has 4,613,903 bodies in it.
 

varonica

varonica
Eahlstan said:
Common misconception. "Tidal locking" and "synchronous rotation" are not synonyms.
As this comes up all the time I asked Orvidius to make a spreadsheet of tidal locked bodies that aren't in synchronous rotation a long time ago (as an in game proof, but it's not the same in reality too). There are so many that he had to limit it to bodies with a difference greater than 50% between rotational and orbital period. To date it has 4,613,903 bodies in it.
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Yeah, tidal locking at it's base is that there is no net change to rotation over the length of the orbit and is indeed often associated with synchronous orbits, I can indeed imagine there are a large number of bodies with tidal locking and no synchronous orbit, I have seen quite a few myself with just casual checking of orbit data. Millions is not surprising!
 

varonica

varonica
Chrystoph said:
Or, you know, "Tidally Locked: (Y/N)"
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Because tidally locked bodies can also have a fast rotation depending on what they are orbiting. So "Tidally Locked (Y/N) with a fast rotation", but the Y/N is superfluous, because it's only actually reporting non-tidally locked bodies with a fast rotation, so every time it would be "Tidally Locked body (N) with a fast rotation", but then the brackets just containing an N are silly and simply don't make sense because there's nothing to relate them to and it never changes, so it could mean No, or Negative, or Nimbus, or anything. So let's use proper grammar and use a prefix added to the beginning of one of the words to convey the same meaning in a much clearer manner, so we use "non-tidally locked body" to convey the object being described clearly without the unnecessary use of brackets and ambiguous single letters, and "with a fast rotation" to describe the behaviour. So it is much clearer to use "non-tidally locked body with a fast rotation." Then we find ourselves needing to shorten it to make it take up less space and still be clear, so it becomes "non-locked body" (because everyone knows we are referring to tidal locking we we refer to locked, so it becomes "non-locked body with a fast rotation." Removing the ambiguous and possibly confusing and unnecessary use of brackets and letters.
 

Chrystoph

Chrystoph
varonica said:
Because tidally locked bodies can also have a fast rotation depending on what they are orbiting. So "Tidally Locked (Y/N) with a fast rotation", but the Y/N is superfluous, because it's only actually reporting non-tidally locked bodies with a fast rotation, so every time it would be "Tidally Locked body (N) with a fast rotation", but then the brackets just containing an N are silly and simply don't make sense because there's nothing to relate them to and it never changes, so it could mean No, or Negative, or Nimbus, or anything. So let's use proper grammar and use a prefix added to the beginning of one of the words to convey the same meaning in a much clearer manner, so we use "non-tidally locked body" to convey the object being described clearly without the unnecessary use of brackets and ambiguous single letters, and "with a fast rotation" to describe the behaviour. So it is much clearer to use "non-tidally locked body with a fast rotation." Then we find ourselves needing to shorten it to make it take up less space and still be clear, so it becomes "non-locked body" (because everyone knows we are referring to tidal locking we we refer to locked, so it becomes "non-locked body with a fast rotation." Removing the ambiguous and possibly confusing and unnecessary use of brackets and letters.
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I tried to stay away from this, but I blew the Willpower check. That was mostly because you twisted my statement so that you were addressing something I didn't say.

Since a Tidally Locked body makes exactly one rotation per orbital period, a fast rotation is meaningless in relation to "Tidally Locked" because it will always be 1.

If it is not a Tidally Locked body, then any reference to that condition is pointless because it unneeded verbiage.

So, programmatically, you would want to define whether the Rotational Period is less than or greater than 1 because either of those conditions indicate that the body is not tidally locked.

That being the case, my original position stands.

In nice, simple BASIC, that amounts to:

If Rotational_Period <> 1 Then Tidally_Locked = False

How you care to define that output to the reader is a different issue. For myself, it would be to present the Rotational Period with a notice when the value of 1 causes the body to be tidally locked:

Rotational Period: xxxx
Tidally Locked: Y (where this only appears when Rotational_Period = 1)

Since the verbiage I am responding to was sloppy, specifically conflating Rotational Period and Rotational Speed, I feel the need to point out that the general concept of Rotational Speed is irrelevant to whether a body is Tidally Locked and only applies singly and locally to the relationship of a body in relationship to the body it is orbiting.
 

Eahlstan

E
Chrystoph said:
I tried to stay away from this, but I blew the Willpower check. That was mostly because you twisted my statement so that you were addressing something I didn't say.

Since a Tidally Locked body makes exactly one rotation per orbital period, a fast rotation is meaningless in relation to "Tidally Locked" because it will always be 1.

If it is not a Tidally Locked body, then any reference to that condition is pointless because it unneeded verbiage.

So, programmatically, you would want to define whether the Rotational Period is less than or greater than 1 because either of those conditions indicate that the body is not tidally locked.

That being the case, my original position stands.

In nice, simple BASIC, that amounts to:

If Rotational_Period <> 1 Then Tidally_Locked = False

How you care to define that output to the reader is a different issue. For myself, it would be to present the Rotational Period with a notice when the value of 1 causes the body to be tidally locked:

Rotational Period: xxxx
Tidally Locked: Y (where this only appears when Rotational_Period = 1)

Since the verbiage I am responding to was sloppy, specifically conflating Rotational Period and Rotational Speed, I feel the need to point out that the general concept of Rotational Speed is irrelevant to whether a body is Tidally Locked and only applies singly and locally to the relationship of a body in relationship to the body it is orbiting.
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As I said before: That's not what tidal locking means.
 

Eahlstan

E
Chrystoph said:
Source(s) please; I can site my usage from multiple supposedly reputable locations.
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I bet you can. It's surely one of the most common confusions out there.

A widely spread misapprehension is that a tidally locked body permanently turns one side to its host.

...

As long as ‘tidal locking’ denotes only the state of dωp/dt = 0, the actual equilibrium rotation period, as predicted by the CTL model of Lec10, may differ from the orbital period, namely when e ≠ 0 and/or ψp ≠ 0 ... As given by Eq. (23), one side of the planet is permanently orientated towards the star if both e = 0 and ψ = 0.
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The best known real world example probably is Mercury: It's tidally locked, but it rotates 3 times every 2 orbits.
 

Stonelaughter

Stonelaughter
Quoted from Wikipedia's page on the topic:
"There is ambiguity in the use of the terms 'tidally locked' and 'tidal locking', in that some scientific sources use it to refer exclusively to 1:1 synchronous rotation (e.g. the Moon), while others include non-synchronous orbital resonances in which there is no further transfer of angular momentum over the course of one orbit (e.g. Mercury).[4] In Mercury's case, the planet completes three rotations for every two revolutions around the Sun, a 3:2 spin–orbit resonance. In the special case where an orbit is nearly circular and the body's rotation axis is not significantly tilted, such as the Moon, tidal locking results in the same hemisphere of the revolving object constantly facing its partner.[3][4][5]Regardless of which definition of tidal locking is used, the hemisphere that is visible changes slightly due to variations in the locked body's orbital velocity and the inclination of its rotation axis over time."
 

Markov Chaney

M
Well, Frontier will be using Frontier's definition. And upthread, Elite Observatory's definition has also been explained very clearly.

Whilst you have Wikipedia open though, you could look up "necroposting."
 
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