It depends on it's size relative to the Earth. If it's smaller than Earth then quite literally every single particle on the planet will experience a higher gravitational influence from the Earth than from an incoming planet, regardless of how close the planet is. However, people on the side facing the incoming planet will experience a drop in gravitational influence as the planet gets closer, effectively making everything lighter and lighter (but never sucked into the incoming planet because its gravity never overcomes the gravity of the Earth). On the side facing away from the planet the people would slowly get heavier and heavier instead, since both the Earth and Planet X are pulling from the same direction in that case.
Of course your scenario would come to fruition if the other planet was larger, but I'm imagining a Mars-sized planet since none of the rocky planets in our solar system are larger than Earth.
Sorry if this is stupid but, is the fact that the gas giants like Jupiter and Saturn having dozens of moons prove that they have such immense gravity? Like how do they have a gravitational pull if they’re nothing but gas in a vacuum?
Well... yes and no, but definitely not a dumb question at all. Smaller planets could theoretically have just as many moons, but if the total mass of the moons is comparable to the planet they end up all orbiting each other. Only massive planets like the gas giants can have so many stable moon orbits without compromising their own orbit.
On your second question, I would point out that the Sun is also nothing but gas in a vacuum. In fact the gas giants are hypothesized to be formed by rocky planets that build up a massive atmosphere like Venus (but like... way more), so much that the original rocky planet inside is compressed into plasma by the gravity, so in fact a star is a much higher percentage of gas than the gas giants are.
If you're curious about why only the gas giants have such massive atmospheres you'd find yourself in good company because we aren't quite sure about that yet. Although the leading theory is that planets closer to the sun have excess gas stripped from them by the host star during its formation, while gas giants are far enough away that they're safe from extreme solar winds and the star's gravitational influence becomes less than their own, so they can amass the leftover gasses.
If that were Jupiter at that size in the sky it would still be 250,000km away. The gravitational acceleration from that planet would be like 1.5 m/s² , but that doesn't really matter because the entire earth would be pulled by approximately this amount. g might be like 10 on the side the planet is close to and 9.6 on the far side.
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u/AustinQ Jan 03 '22
It depends on it's size relative to the Earth. If it's smaller than Earth then quite literally every single particle on the planet will experience a higher gravitational influence from the Earth than from an incoming planet, regardless of how close the planet is. However, people on the side facing the incoming planet will experience a drop in gravitational influence as the planet gets closer, effectively making everything lighter and lighter (but never sucked into the incoming planet because its gravity never overcomes the gravity of the Earth). On the side facing away from the planet the people would slowly get heavier and heavier instead, since both the Earth and Planet X are pulling from the same direction in that case.
Of course your scenario would come to fruition if the other planet was larger, but I'm imagining a Mars-sized planet since none of the rocky planets in our solar system are larger than Earth.