Does our solar system depend on objects outside of the universe?

Does anything outside of our solar system affect the objects within our solar system? Assuming that the system managed to get itself into the state it is now, if only our solar system existed, would life be any different than it is now? At night, the moon would certainly shine, but are the stars (other than Sol) necessary for life (ignoring navigation by the stars)?

Does our solar system depend on the gravitational effects of other external objects, or is our own sun merely enough to keep the solar system from flying apart?

We are pretty independent. Of course, we only exist initially as a solar system due to the ashes of stars and supernova, and the compression of another supernova that kicked the whole thing off.

Otherwise, the solar systems place in the galaxy is maintained by gravity, but from an energy viewpoint, we are self contained. At some point, the solar wind pushing out fades to a point where it matches the interstellar wind pushing back. This is called the heliopause, and marks the limit of the solar system. It also stops low speed interstellar material - it won’t stop fast moving objects.

So - if the rest of the universe disappeared, the only thing we would notice is the stars going out - and a decrease in high energy cosmic rays. In fact, we could be somewhat safer - there are supernova events capable of blasting half the planet with gamma radiation.


Well, our solar system is in orbit around the center of the Milky Way, so I would imagine a great deal of things would change if all that gravity were somehow gone. Now, how much it would change? I don’t know. I’m not an astronomer or a an astro-physicist, so I’ll leave it to others to give the definitive answer, but my first reaction is: the solar system would be very different if the rest of the objects in the universe did not exist.

Nope. The force of gravity is dependent on the ratio of the masses and the (inverse) square of the separation. The influence of a massive object really far away (the centre of the galaxy) on a small object (the earth) is miniscule compared with the influence of a massive object (the sun) quite close. The solar system can be successfully modelled without reference to external objects. If everything else disappeared, we would continue on out merry way in a straight line, and the internal structure of the solar system would not change.


Incidentally, in case this is a genuine misconception rather than a typo in the title: The Solar System is not synonymous with the Universe. The Solar System is just the Sun and the planets and assorted other objects (comets, asteroids, etc.) which orbit it. A galaxy (whch you didn’t mention, but is also often involved in misconceptions like this) is a collection of hundreds of millions or billions of stars; almost everything you can see in the night sky is part of the same galaxy (named the Milky Way) as us. And the Universe is the whole shebang, absolutely everything, including at least hundreds of billions (and possibly an infinite number) of galaxies.

Also, our solar system isn’t anywhere near the center of the Milky Way. Good thing too, cuz there’s a really big black hole there.

Indeed, it was a typo, and not a misconception. I can’t report my own post, so can a mod please change the title to something like “Does our solar system function independently of external objects?” …or something. Thanks!

If you’re interested, this question is explored in detail in Greg Egan’s REALLY cool book Quarantine, where the solar system is cordoned off from the rest of the universe by an impassable black hole-style sphere, and Robert Metzger’s Picoverse (where carbon copies of our solar system, people and all, are spawned off as independent “picoverses” the size of our solar system are created by high-energy physics experiments; they’re called picoverses because the solar system is about one-trillionth the volume of the known universe).

Just for fun, has anyone ever computed the tidal impact of the center of our galaxy on earth? I’d guess it would be in the nanometer range if that.