I recall seeing a paper with orbital dynamical simulations in which they found a 2 percent chance that over the remaining lifetime of the sun, the orbital eccentricity of Mercury would increase such that it interacted with Venus, either hitting Venus or getting boosted onto an Earth-interacting trajectory which could lead to a collision or eject it from the solar system altogether, and which puts Venus on a much more closely Earth-interacting orbit. In one simulation out of the 2,500 they did, Mars’s eccentricity was perturbed until it became Earth-crossing.
Remember that there is a bit of a selection effect when it comes to looking at exoplanets—we see the compact large planet systems much more easily than systems like ours. The latest work I’ve seen has suggested that we are a less common class of star system but that stuff like ours might be something like 10% of star systems. Nobody REALLY has a handle on planet formation yet, and it looks like there may be several very different ways that planets and planet-forming material can migrate around the protoplanetary disc during the planetary accretion stage that people argue bitterly over in the literature.
I recall seeing a paper with orbital dynamical simulations in which they found a 2 percent chance that over the remaining lifetime of the sun, the orbital eccentricity of Mercury would increase such that it interacted with Venus, either hitting Venus or getting boosted onto an Earth-interacting trajectory which could lead to a collision or eject it from the solar system altogether, and which puts Venus on a much more closely Earth-interacting orbit. In one simulation out of the 2,500 they did, Mars’s eccentricity was perturbed until it became Earth-crossing.
Remember that there is a bit of a selection effect when it comes to looking at exoplanets—we see the compact large planet systems much more easily than systems like ours. The latest work I’ve seen has suggested that we are a less common class of star system but that stuff like ours might be something like 10% of star systems. Nobody REALLY has a handle on planet formation yet, and it looks like there may be several very different ways that planets and planet-forming material can migrate around the protoplanetary disc during the planetary accretion stage that people argue bitterly over in the literature.