My understanding is that Venus, Earth, Mars, and Jupiter are all losing mass due to their gravity, temperature, and the solar wind. But what about Mercury, Saturn, Uranus, and Neptune? Mercury has a magnetic field and so typically would repeal the worst of the solar wind and no atmosphere to lose, only an exosphere. Though the Poynting-Robertson effect should be pulling in more dust to Mercury. I do not know the calculations to determine if Saturn, Uranus, and Neptune are losing mass though.
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2$\begingroup$ What? That's a step hypotheses to make that anything loses mass due to its own gravity. Any proof of that? $\endgroup$– planetmakerCommented Feb 28, 2020 at 21:54
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$\begingroup$ @planetmaker My statement was that the amount of gravity is a factor that affects mass loss, the less gravity the more you lose and vice versa. $\endgroup$– Brooks NelsonCommented Mar 2, 2020 at 16:47
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1$\begingroup$ Gravity might strength of some effects, but it never is the cause of any mass loss like you claim in your question. Of all planets listed, Mercury certainly is not an example for a particularily strong magnetic field either (though for an interesting one). I think you should elaborate your question a bit more on the base assumptions you base it on. Maybe read en.wikipedia.org/wiki/Atmospheric_escape $\endgroup$– planetmakerCommented Mar 2, 2020 at 17:02
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$\begingroup$ @planetmaker When I refer to gravity it is more accurate to say I am referring to escape velocity. Which is dependent on the mass and distance from the center of the mass of the object. Gravity is what we tend to refer to when in regards to what is force is measured at the surface and is why I used it. en.wikipedia.org/wiki/Escape_velocity $\endgroup$– Brooks NelsonCommented May 1, 2020 at 15:39
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1$\begingroup$ You should say what you mean or you will never mean what you say ;) Accuracy in expression is important - especially in physics. Escape velocity does play a role when considering mass changes of planets. But it is by far not the only variable in that equation $\endgroup$– planetmakerCommented May 1, 2020 at 20:10
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2 Answers
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I'm not sure how the balance between mass loss and gain works out...
Yes, atmospheric escape is probably happening to some extent on all the planets, with rates that depend on escape velocity, magnetic field, atmospheric/exospheric composition, temperature, and other effects we are still learning about.
But the planets are also gaining mass by capturing dust, meteorites, and the occasional larger object that can cause cratering on solid bodies, or atmospheric debris clouds in giant planets like Jupiter.
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1$\begingroup$ +1, maybe what's missing to this answer: Many effects in physics exist, but whether they matter significantly is another question. Numbers on escape rates for the lightest species for the lightest planets, closest to the sun (i.e. the terrestrials) from ui.adsabs.harvard.edu/abs/2018A%26A...614L...3G/abstract show that you'd loose about 10% of the Martian atmosphere in ions under current solar conditions during 1 Gyr. That's not very much, and as for the gain mechanisms, their magnitude is unknown. Loss for the (giants) will be correspondingly weaker. $\endgroup$ Commented Nov 30, 2021 at 23:04
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Anything that's working, spending energy is losing mass, Einstein Mass-energy equivalence of SR along with radiant energy(electromagnetic and gravitational radiation) would be effecting all the planets, but at a different rate for each one. https://en.m.wikipedia.org/wiki/Radiant_energy
And. https://en.m.wikipedia.org/wiki/Mass_in_special_relativity
These should help I think
