why does predicting things in space (outside the planet) seem to be a lot easier than predicting weather on Earth?
In: Physics
Earth’s enviro-sphere is pretty complex. Interactions between ground temperature, planetary albedo, minutes of sunlight, time of year, snow, water, foliage cover, water temperature, ocean currents, the magnetosphere, ionosphere, im-probably-forgetting-a-sphere, wind speed, air pressure, air _quality_, all are one big non-linear complicated mess that we _think_ we know how to simulate (obviously, our forecasts are pretty good), but probably have only just scratched the surface on. I mean, there’s a reason why more accurate climate and weather change prediction models need to run on supercomputers.
Stuff in space on the other hand, by and large, follows Newtonian physics. At least as far as most practical purposes. An object at motion stays in motion etc. Once something is orbiting something larger, it either continues to orbit, the orbit decays or is perturbed, or something accelerates or perturbs it out of that orbit.
For most purposes, every body in our solar system can be thought to be as part of one or two two-body systems. Earth orbits the Sun. The moon orbits Earth. Apollo capsule orbits the Moon. Is it true that the sun affects the orbit of a capsule in orbit around the Moon? Absolutely it does. So does the Earth. BUT, since gravity is inversely proportional to the distance, the effect of the closer body has a much more significant effect; often to the point that the other bodies’ effects are negligible.
Having said that, we do have a good idea of how say Jupiter’s gravity affects Earth’s orbit around the sun (exactly how and how much of an effect it is I don’t know, but its there), but its impact is somewhat negligible compared to the math of us flying to the Moon or Mars or whatever.
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