When the Earth orbits around the sun, relatively speaking, does it circle in the same path each time?
In: 184
No.
Reason #1: our solar system is moving through the galaxy, so after the Earth has gone around the sun, the Sun is now in a new spot, so the Earth can’t be in the same spot again.
If you’re just talking about the Earth relative to the Sun, the answer is still no.
Reason #2: Everything has a gravitational pull. All the other planets are pulling on each other (and even our moon) so every year the Earth is pulled around slightly differently based on the position of the planets.
Any gravitational system with more than 3 bodies is chaotic (meaning very sensitive to the initial conditions), and it usually ends up with one body being ejected. Our solar system being in tact with so many planets over billions of years just means that we got lucky. We have no idea if a planet will be ejected in the next billion or so years, though.
Reason #3: general relativity. Gravity slows down time, and this affects the way planets orbit. If you look at Mercury’s orbit over several years, you’ll see that it actually drifts around (this is called the orbital precession) and it makes the orbit look more like a flower shape if you map it out over a few hundred years. This same thing happens to all the planets, but it’s much easier to notice with Mercury because it’s so much closer to the Sun, so it’s more strongly affected by the sun’s gravity.
For any purposes during your lifetime, the path of the Earth won’t change that much. It will be closest to the Sun in January (147 million km) and furthest away in July (152 million km) and take 365.2422 days to complete that orbit and that’s more information than you’ll ever need to worry about.
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