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Questions tagged [tidal-forces]

Questions about the apparent force stretching a body towards and away from the center of mass of another body due to the variance in acceleration due to gravity

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Earth-Moon receding-approaching cycle?

I made the following question in an another more informal forum of discussion on physics: My question comes after reading this article: https://www.coastreporter.net/in-the-community/the-moon-is-...
vengaq's user avatar
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3 votes
2 answers
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Will the Moon recede far enough that the Earth-Moon barycenter lies outside of Earth's radius before the Sun becomes a red giant?

As most people know, the Moon is receding from Earth at a rate of a few centimeters per year. This rate is not constant; as the Moon gets farther away, the tides it raises will be weaker and thus will ...
user267545's user avatar
3 votes
3 answers
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Would a planet's tidal forces really push away a moon out of its Hill Sphere?

If a moon orbits in the same direction as its planet's rotation (i.e. a prograde orbit), and its orbital period is longer than its planet's rotational period, then tidal forces would cause the moon to ...
user267545's user avatar
16 votes
3 answers
3k views

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

The recent question How do we know the Moon was much closer than it is now? has piqued my interest. The answers are numerous and clear. But I started to wonder. The question includes the following ...
uhoh's user avatar
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3 votes
3 answers
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Will all satellites get inevitably tidally locked to their planet?

Are there cases or conditions in which an object orbiting another one (e.g. a satellite and its planet) does not get tidally locked to it? For example, in this question, it is mentioned that a large ...
vengaq's user avatar
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1 vote
1 answer
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Will the Earth tidally lock to the Moon (ignoring Sun's expansion)

At some point, won't the tidal forces from the Moon be less than the ones from the Sun? Would that mean that the Moon stops moving away, or would the process still continue. Would the Earth start ...
user138890's user avatar
2 votes
3 answers
271 views

What does the rate the Moon moves away from Earth depend on?

Is it based on the distance between the Earth and Moon? Would that make the Moon move away faster or slower as time goes on?
user138890's user avatar
12 votes
1 answer
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Would the Earth and Moon still have tides after the Earth tidally locks to the Moon?

Ignore the Sun's expansion. From my understanding, tidal locking happens from torque as a result of tidal bulges being offset from the line between the two planets. So when the Earth and Moon tidally ...
user138890's user avatar
-2 votes
2 answers
162 views

What would a gas giant, such as Uranus, look like if it were orbiting a sun like star at an Earthlike orbit?

This is a hypothetical. If a gas giant with the approximate mass and density of Uranus existed within the goldilocks range to support life around a star, what would be the conditions on the service. ...
Curious Gorge's user avatar
8 votes
2 answers
1k views

Do tidal forces on moons cause them to emit gravitational waves?

As moons orbit planets, they get squashed by uneven gravitational forces acting on them. Does this make a moon emit gravitational waves?
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What is the best estimate for the radius of Shoemaker-Levy 9?

I have been digging through various scientific articles on modelling the breakup of SL9 to attempt to ascertain its intial size, yet the various estimates vary tremendously. A radius of 700 m - 1000 m ...
Gregor Hartl Watters's user avatar
1 vote
2 answers
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What's the difference between perigean spring tide and proxigean spring tide? [closed]

Also, is proxigean spring tide a special case of perigean spring tide ? Are there other kinds of tides other than spring, neap, proxigean spring, and perigean spring tide ?
imdevskp's user avatar
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What would happen if all water on earth including the oceans was placed evenly over the atmosphere of Earth? [closed]

Would that massive water body sit on top of the atmospheric bubble or would it fall to the ground? Would it rain water or fire instead? Would we see the skyes red instead of blue? What would be the ...
Lerian Acosenossa's user avatar
2 votes
2 answers
2k views

What kind of effects would two moons have on an earthlike planet?

On Earth our moon has several effects: it generates two high and two low tides a day; it slows down the spin of the planet and stabilizes its wobble, etc. So, what possible effects could two moons, ...
CuriousExplorer's user avatar
27 votes
8 answers
8k views

Why, since Earth is in free fall towards Sun, are tides affected by Sun's gravity? Why aren't the oceans "weightless" like astronauts?

Astronauts on the space station do not feel the Earth's gravity at all; they are in free fall. Since the Earth and all that's on it is in free fall toward the Sun, why would the oceans "feel"...
GulbenkianD's user avatar
9 votes
2 answers
3k views

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? Would they change throughout an elliptical orbit, due to changing distance from the star? How exactly would they ...
Elhammo's user avatar
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Tidal potential expression using eccentricity

I'm reading these excellent lecture notes about tidal dissipation, and they mention at some point that the time-dependent part of the tidal potential is approximated by (Eq. 17.1 on the third page): $$...
ValientProcess's user avatar
2 votes
1 answer
157 views

Are there tidally locked bodies where the "far side" is denser?

It makes sense that tidal forces lead to tidal locking. Celestial bodies have varying densities and shapes, so some orientations have a lower gravitational potential, and eventually the tendency will ...
kotoole's user avatar
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3 votes
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If Earth was a moon of Jupiter orbiting at the same distance as Metis (Jupiter's innermost moon), then how much lighter would a 100 kg person feel?

Metis is Jupiter's innermost moon, orbiting at a semi-major axis of 128,000 km. If Earth were to magically replace Metis, then how much lighter would a human weighing 100 kg be? There's no need to ...
user177107's user avatar
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3 votes
1 answer
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Best way to quantify the tidal stress on an exoplanet?

I'm trying to assess the tidal stresses different exoplanets experience during their orbits. The known parameters are usually mass $M$, radius $R$, eccentricity $e$, orbital period $T$, and semi-major ...
ValientProcess's user avatar
4 votes
1 answer
418 views

Why circularization of an orbit has longer time scale than tidal locking?

I'm trying to understand the basic physics of orbital evolution. I know that in a two-body system (a planet orbiting a sun for example), eccentric orbits become circular, and the spin of the planet ...
ValientProcess's user avatar
0 votes
1 answer
54 views

could we use tidal forces H.E.P for energy on ceres asteroid [closed]

to make energy could we use the tidal forces in the water under Ceres surface?
tom's user avatar
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3 votes
1 answer
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Is there an official recommended expression for Doodson arguments?

I am following chapter 6 of this 2010 IERS note describing the calculation of a geopotential model. In the notes of equation 6.8, two expressions for the parameter called $\theta_f$ is given. One of ...
Rafa's user avatar
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5 votes
1 answer
657 views

Difference between fluid Love number and tidal Love number

I'm trying to understand more about tidal deformation in planets, and I frequently encounter Love numbers. However, sometimes the fluid Love number is mentioned, and sometimes the tidal Love number is ...
ValientProcess's user avatar
3 votes
1 answer
673 views

Is the high-low tide difference greater, on average, at new moon, full moon, or neither?

The difference between high tide and low tide peaks when the moon is full and also when the moon is new. At both of these points in the lunar cycle, the tides are known as "spring" tides. On ...
ool's user avatar
  • 130
2 votes
1 answer
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Relative orientation in a 1:1 resonance of a planet and a satellite

To my understanding, in a two-body problem of a planet and a satellite, a 1:1 resonance means that the orbital period of the satellite is the same as its angular frequency (maybe not, so please ...
ValientProcess's user avatar
25 votes
2 answers
3k views

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

According to its Wikipedia page: Rotation period: synchronous Eccentricity: 0.0041 But also ...extreme geologic activity is the result of tidal heating... How is it possible? It should not be ...
peterh's user avatar
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6 votes
1 answer
99 views

Physical Meaning of the Principal Tidal Fourier Modes and Their Integers

I'm trying to understand tides evolution of planets, and I often come across the Prinicipal Tidal Fourier Modes expressed as: $$ \omega_{lmpq}$$ For example, see the discussion after Eq. A15 in ...
ValientProcess's user avatar
4 votes
1 answer
94 views

Can we measure planetary Love number of exoplanets?

I understand that Love number is the ratio between the tide raising potential to the actual deformation of the body, however, I'm not sure if there are ways to detect the Love number from observations ...
ValientProcess's user avatar
9 votes
4 answers
2k views

Is there any difference between tidal locking and synchronous rotation?

I'm trying to understand more about orbital mechanics, and I'm encountering a few terms which I'm not sure if they are exactly the same. The two terms are Tidal Locking and Synchronous Rotation. To my ...
ValientProcess's user avatar
2 votes
2 answers
120 views

Why does the difference between terrestrial times and universal time, $\Delta T$, have such a strange behaviour?

I was reading about ancient astronomy, and one of the main phenomena described is eclipses. Now, I read this 2016 paper by Stephenson, Morrison and Hohenkerk, in which they determine the values of the ...
Don Al's user avatar
  • 121
0 votes
3 answers
240 views

What would I experience on a planet orbiting close to a black hole? [closed]

I can't get my head around it completely. I am standing on an Earth-sized planet circling a black hole. Let's assume the planet to be an incompressible one. It is observable that matter is sucked in ...
Deschele Schilder's user avatar
23 votes
3 answers
5k views

If we replaced the Moon with Ceres, how close would Ceres have to orbit to cause the same tides?

How close to Earth would Ceres have to be to cause tides of the same strength as by the Moon, above the region it orbits? Ceres has 1.3% the Moon's mass, but that doesn't mean it must be at 1.3% the ...
John's user avatar
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1 vote
0 answers
71 views

Understanding various conditions where a star and a black hole meet and there is no tidal disruption; what all can we infer from this diagram?

Can an entire star pass through the event horizon of a black hole unharmed? is a one sentence HNQ with an amazing (to me at least) answer: for supermassive black holes larger than roughly 100 million ...
uhoh's user avatar
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6 votes
1 answer
266 views

Tidally locked Venus, is it possible and consequences?

Suppose, Venus becomes tidally locked. Will its dark side cool enough so that the CO2 from the atmosphere to precipitate in liquid form to make an ocean? Also, I wonder, how close Venus is to becoming ...
Anixx's user avatar
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6 votes
1 answer
81 views

Calculating the radial tidal amplitude on a planet from the fluid Love numbers

How do you calculate tidal amplitudes from the fluid Love numbers? In my course on planetary physics I saw an approximate expression for the displacement from equilibrium tide: $$\Big|\frac{V_T}{g}\...
theWrongAlice's user avatar
1 vote
0 answers
33 views

If you are standing on the shore and it is high tide, what are the two possible locations for the moon relative to where you are? [duplicate]

Science Class If you are standing on the shore and it is high tide,
Simone Henry's user avatar
0 votes
1 answer
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Lunar Inclination

Are there published tables for Lunar Inclination? I am interested because I believe this determines the degree of "Diurnal Inequality" of tides. There are tons of publishes tables of tides ...
DontPanic's user avatar
  • 103
3 votes
2 answers
313 views

Is there a way to estimate or calculate the tidal range induced on a water-bearing planet?

Consider a system in which a central star is orbited by a planet with liquid water oceans, which is itself orbited by a moon. Given the masses and distances between these three objects, is there some ...
KeturiosBlue's user avatar
1 vote
0 answers
36 views

How to explain tidal tails and dark matter sub-halos in simple terms?

There is the exciting news by ESA entitled Is the nearest star cluster to the Sun being destroyed? Data from ESA’s Gaia star mapping satellite have revealed tantalising evidence that the nearest ...
B--rian's user avatar
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5 votes
2 answers
594 views

How much lighter would someone be on the Jupiter-facing side of Io?

Io is the Galilean moon closest to Jupiter. Its average surface gravity is 0.183g and it has a tidal lock with Jupiter. So if you stood on the near side of Io at the equator, how much lighter would ...
Greenhorn's user avatar
6 votes
1 answer
198 views

Do moons of rocky oblate planets migrate to low inclination over time? If so, does the time it takes depend on the Moon's size?

Discussions elsewhere suggest that this happens and that smaller moons would tend to low inclination with respect to the planet's equator faster than larger ones. For example, Mars' small moons are ...
uhoh's user avatar
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29 votes
1 answer
2k views

A moon in eccentric orbit dipping below Roche limit

Let's imagine (or do we know one?) a moon in a very eccentric orbit around a planet, with periapsis below the Roche Limit. How would it behave? Would it break apart when speeding past the planet, then ...
SF.'s user avatar
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6 votes
2 answers
1k views

Can moons exist inside a planet's roche limit?

Saturn's rings are inside its own Roche Limit - the limit beyond which bodies start disintegrating due to the tidal forces of the parent body. But as every rock in the ring can be regarded as a ...
Astro Noob's user avatar
5 votes
1 answer
409 views

Is a three body gravitating system doomed to collapse?

Suppose we have two gravitating bodies, which are rotating around each other. They are bodies and are affected by deformation caused by tidal forces. Moving tidal waves suck energy from the axial ...
Askold Ilvento's user avatar
0 votes
0 answers
50 views

The possibility of rapidly changing the Earths orbit via a passing astronomical object

I assume that the Earth could be “gently” (without colossal tidal or volcanic catastrophe) displaced by a passing extra solar star, brown dwarf or planet and end up perhaps 10% further away from the ...
Slarty's user avatar
  • 359
2 votes
2 answers
198 views

Why doesn't Earth's leading tidal bulge cause the Moon to start spinning in the opposite direction than its original spin?

Please refer to the image below: My question is, why doesn't Earth's leading tidal bulge (encircled in the green circle 1) pull on the moon's tidal bulge (encircled in green circle 2), leading to a ...
Shikhin Mehrotra's user avatar
1 vote
2 answers
537 views

Considering that the moon’s gravitational pull on earth is so weak- we need special instruments to detect it- how does it cause the tides?

That the moon’s gravitational pull is responsible for the tides is established. However, if we want to detect the moon’s gravitational pull on earth, this is very challenging. This seems to be a ...
James's user avatar
  • 19
4 votes
2 answers
3k views

How high were the tides back when the Moon was much closer to Earth?

In this article it is stated that the Moon was originally much closer to Earth at a distance of 22,500 km rather than the 384,400 km it is today. What was the height of the tides back then in meters? ...
user177107's user avatar
  • 2,689
5 votes
1 answer
130 views

Would a satellite that has a retrograde orbit and a shorter orbtial period than its planet's rotational period be tidally accelerated or decelerated?

There are 4 configurations to consider. A satellite orbiting a planet that: Has a prograde orbit and larger orbital period than its planet's rotational period (example: The Moon) Has a prograde ...
user267545's user avatar