34 votes
Accepted

How can Io be tidally heated while it is in tidal lock?

How can Io be tidally heated while it is in tidal lock? It is tidally locked in a mean motion sense of "tidally locked". That Io is in an eccentric orbit rather than a circular orbit means ...
David Hammen's user avatar
  • 33.7k
27 votes
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Shouldn't tidal locking be impossible for a satellite that has a considerably eccentric orbit?

You are right, that would be weird if the Moon speeds up and slows down this way to always show the exact same side to the Earth. That's why it doesn't. At some point in the orbit the Moon's rotation (...
SpaceCore's user avatar
  • 2,993
26 votes
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Would the Earth and Moon still have tides after the Earth tidally locks to the Moon?

There won't be significant lunar tides. The moon will become fixed at one location above the Earth. The tidal forces that drive the resonant water flows that we call "tides" will be fixed. ...
James K's user avatar
  • 118k
21 votes

Under which conditions could a planet's massive moon's orbit get closer to the planet?

Yes, it is possible for a moon of a planet to move closer to the planet. If a moon moves close enough to the planet, the moon will eventually reach its Roche limit and shatter or else collide with ...
M. A. Golding's user avatar
20 votes

"Tidally locked" Oort Cloud object

The question in the title and the body are different. There are no tidally locked objects in the Oort cloud. The sun's tidal forces at that distance are not sufficient to lock an object's rotation. ...
James K's user avatar
  • 118k
19 votes

Will the Earth ever be tidally locked to the Moon?

As the moon orbits Earth, tidal forces slow down the Earth's rotation by 2 milliseconds per century. Eventually, in tens of billions of years, the Earth and Moon would achieve a double tidal lock, ...
called2voyage's user avatar
  • 6,312
16 votes

How would ocean tides work on a tidally-locked planet?

Since the tidal bulge is always in the same place, how would that affect ocean tides? The concept of tidal bulge is a useful fiction, but fiction nonetheless. For an object in an eccentric orbit, the ...
David Hammen's user avatar
  • 33.7k
13 votes

How can Io be tidally heated while it is in tidal lock?

That sentence on wikipedia continues "from friction generated within Io's interior as it is pulled between Jupiter and the other Galilean moons". There's an orbital resonance (with the other ...
Luaan's user avatar
  • 498
12 votes
Accepted

Effects of a binary star system on a tidally locked planet

The "three-body" problem and its stability are still an unsolved problem in general. There are papers that do long term integrations of planet orbits in binary systems to study their ...
ProfRob's user avatar
  • 149k
11 votes

Is the moon "perfectly" tidally locked and, if not, how long would it take us to observe it's rotation?

The Moon indeed "wobbles" about in its orbit because it goes around the Earth in an ellipse and not a circle. From our point of view, it wobbles a little back and forth such that over a lunar cycle, ...
Dave's user avatar
  • 801
11 votes
Accepted

Is the moon "perfectly" tidally locked and, if not, how long would it take us to observe it's rotation?

The question is interesting, but I suspect the answer is that the Moon will never show its "far side" to the Earth, because there are differences between the side that faces us and the far ...
Ken G's user avatar
  • 5,320
10 votes

Will Mercury ever become locked to the Sun?

Mercury is tidally locked; it has a 3:2 resonance with the Sun, where it rotates three times for every two orbits. It is well understood that Mercury is tidally locked, but modern explanations for how ...
Justin T's user avatar
  • 3,404
10 votes

Under which conditions could a planet's massive moon's orbit get closer to the planet?

Under which conditions could a planet's massive moon's orbit get closer to the planet? I'll give the most straightforward condition: The tidal interaction tends to accelerate the orbiting moon in the ...
Sten's user avatar
  • 4,501
9 votes
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Is it coincident that all planets with tight orbit are tidally locked to their parent body?

This is a physical result: The change in rotation rate necessary to tidally lock a body B to a larger body A is caused by the torque applied by A's gravity on bulges it has induced on B by tidal ...
J. Chomel's user avatar
  • 1,452
9 votes
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Has the Earth-facing side of the Moon that we see today always faced us ever since the Moon got tidally locked? Or does it precess?

The Earth-facing side of the Moon doesn’t change currently due to any of the forces on it by other bodies (excepting librations). From Gladman et. al.: “tidal dissipation in the satellite drives it to ...
Connor Garcia's user avatar
  • 16.3k
9 votes
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"Tidally locked" Oort Cloud object

Suppose you orbit with period $P$, and have a angular velocity $\omega$ randomly chosen (let's start with everything aligned in a plane orthogonal to spin too). Then to keep your face pointed towards ...
Anders Sandberg's user avatar
8 votes
Accepted

Would a tidally locked planet be always increasing in temperature?

Hot objects radiate heat. The hotter something is, the faster it radiates heat. The side of the planet that faces the sun would heat up until the rate at which it is absorbing heat from the star is ...
James K's user avatar
  • 118k
8 votes
Accepted

Why isn't Earth tidally locked to the sun?

Really, it's just because the tidal locking timescale is so long for Earth: $$t\propto\frac{a^6m_{s}}{m_{p}^2R_s^3}$$ where $a$ is semi-major axis, $m_s$ is the mass of the secondary object, $m_p$ is ...
HDE 226868's user avatar
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8 votes

As the Moon and the Earth are predicted to get into tidal lock, how slow would the Earth rotate?

The last part of the answer you linked to actually says (right at the end) that tidal locking will never be achieved, with reasoning similar to what I gave in this answer. That said, even though the ...
Eric Jensen's user avatar
  • 4,864
8 votes

Shouldn't tidal locking be impossible for a satellite that has a considerably eccentric orbit?

With a more eccentric orbit, tidal control of the rotation does not lead to a librating lock. Mercury is in a 3:2 spin-orbit resonance. Hyperion's spin is chaotic: it gets a quasi-random kick each ...
John Doty's user avatar
  • 1,726
8 votes
Accepted

Tidally locked Venus, is it possible and consequences?

It may not be possible for Venus to become tidal locked I don't think we know if it's possible for Venus to become tidally locked. Correia et al. 2008 expect the equilibrium rotation to differ from ...
Connor Garcia's user avatar
  • 16.3k
8 votes

Under which conditions could a planet's massive moon's orbit get closer to the planet?

Both Sten and M.A.Golding have provided good answers, so I shall only add some details. (1) The tides exerted in the planet by the moon are pushing the moon away when its semimajor axis' exceeds the ...
Michael_1812's user avatar
  • 1,231
7 votes
Accepted

A "tidally locked" double planet?

Your scenario isn't stable. A simple way to explain this is to imagine that the planet's orbit each other at the same rate they orbit the star (your scenario has them orbiting even slower). At the ...
userLTK's user avatar
  • 23.9k
7 votes
Accepted

Earth rising and setting from moon's perspective

You're quite right. The Earth is (nearly) stationary in the Moon's sky. (I say "nearly" because the Moon is in a slightly elliptical orbit around the Earth, but rotates perfectly smoothly. This ...
Mark Olson's user avatar
  • 7,620
7 votes
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Why circularization of an orbit has longer time scale than tidal locking?

Tidal locking is a primary effect due to a direct torque on a body from its tidal bulge lagging its rotation. This is pictured nicely on wikipedia with an example from the Earth/Moon system. Tidal ...
Connor Garcia's user avatar
  • 16.3k
7 votes
Accepted

Is this definition of tidal locking really satisfying?

Currently, the Moon is tidally locked to the Earth but the Earth is not tidally locked to the Moon. In your scenario (which could be accomplished by raising the mass of the Earth), where the Moon has ...
Sten's user avatar
  • 4,501
7 votes

Is this definition of tidal locking really satisfying?

Rather than your question (which Sten has already answered well), let me reply to one of your comments under Sten's answer, since I think that's where the core of your misunderstanding lies: In this ...
Ilmari Karonen's user avatar
6 votes

Can a solar system exist where the second planet rotates fast, and the third planet is tidally locked to their star?

The tidal locking timescale depends on several factors: $$\tau_{lock} \approx \frac{0.4 \omega_0 a^5 m Q}{3 G M^2 k_2 r^3}$$ such as the initial spin rate $\omega_0$, the semimajor axis $a$, the mass $...
Anders Sandberg's user avatar
6 votes
Accepted

Is there any residual oscillation left from the Moon rotation?

This is called "physical libration". The Moon’s physical librations and determination of its free modes (2011) estimates it using the Apollo mission retroreflectors. Their result is very small. They ...
Keith McClary's user avatar

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