<p>Let's suppose that a passing planetary mass object pulls mars into an even more eliptical solar orbit, not accounting for other planets, to what degree of eccentricity would be needed for, let's say tectonic/geologic/volcanic activity to start. In other words, what degree of eccentricity would mars need to be in for tidal forces from our sun to exert a noticeable effect on the planet, and further, what would be needed for it to become as active as io? Would it need to pass within the orbit of mercury? Or would just a a dozen degrees be enough? And would it be possible for such activity to start after just a few centuries? My basic understanding is that both eccentricity of its/its companion/moons orbit as well as  proximity to an object of substantial mass will tug on the material of said body on the side facing the other which in turn is translated to thermal energy which is greater depending on proximity/eccentricity/mass? And the greater the orbital eccentricity the more intense the force is at perihelion? Correct me if I'm wrong of course, however I have not taken any formal astrophysics courses yet so I  do not know the equations to get the answer to this.</p>

CC BY-SA 4.0
2024-06-15T17:54:31.160Z
Mars is probably already volcanically active, on geological timescales.
James K
CC BY-SA 4.0
2024-06-17T20:03:34.227Z
Tidal forces are proportional to r^3, meaning that at the distance of Mars, changing its already large eccentricity would not have the same effect as the same eccentricity change it would if Mars were at Earth's orbital distance.  Mars is also smaller than Earth, and tidal force is the difference in gravity at one side of an object versus another, so again, conceptually, you'd have to increase eccentricity a lot more than you would for a larger planet.
Stuart Robbins
CC BY-SA 4.0
2024-06-18T01:14:14.947Z
@StuartRobbins As I have mentioned above I do know know many equations, when you say r^3, is that proportional to the amount of tidal force per degree of eccentricity or by orbital radius? Or something else all together
ArchiveOfStars
CC BY-SA 4.0
2024-06-18T20:37:36.970Z
I should've written 1/r^3.  It means that the amount of tidal force you get goes down as the cube of the distance from the body doing the tidal pulling.  Gravity is a 1/r^2 force, by comparison.  That means that as you go farther away from the sun, the tidal force goes down really fast.  All things being otherwise equal, if Earth were 2 AU from the sun instead of 1 AU, the tidal force experienced by it from the sun would be 1/8 as much (as it is now, the sun's tides on Earth are about 45% as strong as the moon's).
Stuart Robbins
CC BY-SA 4.0
2024-06-19T20:58:51.047Z
@StuartRobbins ohh, so earth at .5 au would experience solar tides four times stronger than lunar tides? Anyway do you know the ratio/percentage of solar tides on earth compared to jovian tides on io? Also I've heard sources state that orbital eccentricity also has effect on tidal forces (I've heard sources say that mimas being kicked into a more eccentric orbit caused it's ocean to form) do you know how/what the relation is?
ArchiveOfStars
CC BY-SA 4.0
2024-06-26T14:36:13.380Z
The tidal heating from the passing planet would be more significant.
eshaya
<orbit><mars><tidal-forces><volcanism>
Could mars become volcanically active if it is pulled into a highly eccentric orbit
ArchiveOfStars
# Could mars become volcanically active if it is pulled into a highly eccentric orbit

(Asked by: username_0 on 2024-06-15)

Let's suppose that a passing planetary mass object pulls mars into an even more eliptical solar orbit, not accounting for other planets, to what degree of eccentricity would be needed for, let's say tectonic/geologic/volcanic activity to start. In other words, what degree of eccentricity would mars need to be in for tidal forces from our sun to exert a noticeable effect on the planet, and further, what would be needed for it to become as active as io? Would it need to pass within the orbit of mercury? Or would just a a dozen degrees be enough? And would it be possible for such activity to start after just a few centuries? My basic understanding is that both eccentricity of its/its companion/moons orbit as well as proximity to an object of substantial mass will tug on the material of said body on the side facing the other which in turn is translated to thermal energy which is greater depending on proximity/eccentricity/mass? And the greater the orbital eccentricity the more intense the force is at perihelion? Correct me if I'm wrong of course, however I have not taken any formal astrophysics courses yet so I do not know the equations to get the answer to this.

**Tags:** orbit, mars, tidal-forces, volcanism

> **Comments:**
> **username_1**: Mars is probably already volcanically active, on geological timescales.  
> **username_2**: Tidal forces are proportional to r^3, meaning that at the distance of Mars, changing its already large eccentricity would not have the same effect as the same eccentricity change it would if Mars were at Earth's orbital distance.  Mars is also smaller than Earth, and tidal force is the difference in gravity at one side of an object versus another, so again, conceptually, you'd have to increase eccentricity a lot more than you would for a larger planet.  
> **username_0**: @StuartRobbins As I have mentioned above I do know know many equations, when you say r^3, is that proportional to the amount of tidal force per degree of eccentricity or by orbital radius? Or something else all together  
> **username_2**: I should've written 1/r^3.  It means that the amount of tidal force you get goes down as the cube of the distance from the body doing the tidal pulling.  Gravity is a 1/r^2 force, by comparison.  That means that as you go farther away from the sun, the tidal force goes down really fast.  All things being otherwise equal, if Earth were 2 AU from the sun instead of 1 AU, the tidal force experienced by it from the sun would be 1/8 as much (as it is now, the sun's tides on Earth are about 45% as strong as the moon's).  
> **username_0**: @StuartRobbins ohh, so earth at .5 au would experience solar tides four times stronger than lunar tides? Anyway do you know the ratio/percentage of solar tides on earth compared to jovian tides on io? Also I've heard sources state that orbital eccentricity also has effect on tidal forces (I've heard sources say that mimas being kicked into a more eccentric orbit caused it's ocean to form) do you know how/what the relation is?  
> **username_3**: The tidal heating from the passing planet would be more significant.  

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