Does our heliosphere reach Alpha Centauri?

Is our heliosphere touching the astrosphere of Alpha Centauri? Would it be visible?
The heliosphere is the sphere around our own sun, where the wind from our sun is much stronger than the wind from anywhere else in our galaxy. The solar wind blows out almost equally in all directions from the sun, making a sphere around our sun. The name heliosphere is pretty unimaginative - helios is just the Greek word for ‘sun’, and sphere is sphere - so it’s a sunsphere which surrounds our solar system. The edge of this sphere is called the ‘heliopause’, and is often used to mean the “edge” of our Solar System. Beyond the heliopause, the direction of the wind changes - we leave the bubble our sun has made, and enter an area in between stars - the galaxy’s wind is the largest player here. As far as we can tell, there’s no visible sign that you’re hitting the heliopause.

We don’t know much about this edge of our solar system - this is largely because it takes a very long time to get that far out, and we haven’t sent that many spacecraft out there. That said, Voyager 1 and Voyager 2 were sent out with the hopes of studying the heliopause, and what it means to leave our solar system.

Voyager 1 has recently been in the process of leaving the heliopause, but it turns out that leaving the solar system is not as straightforward as we had guessed! Originally we had thought that Voyager would leave, like escaping from a bubble - quickly. Instead we’ve had about 3 or 4 false alarms, where one of our expected symptoms of leaving has appeared, but not all of them. So if you remember a few “Voyager Has Left The Solar System” headlines, that’s not your memory playing tricks on you - there have been more than one occasion where we’ve though it had, and then worked out that it hadn’t.

In any case, it seems that the heliopause is somewhere around 121 AU from the sun, which works out to 0.0019 light years. (That’s two thousandth’s of a light year.) The nearest star, Alpha Centauri, is over 4 light years away; literal orders of magnitude further.


The solar system doesn’t actually end at the heliopause, though. Outside the heliopause is the Oort Cloud, which is a sphere of small-ish lumps of ice surrounding our solar system, and is the source of all of (or most of) our comets. The Oort cloud is huge - it starts somewhere around several thousand AU away from the sun, and continues for a few tens of thousands of AU. It’s possible it extends as far as 3 light years away from our sun. Even that won’t get near Alpha Centauri - there’s another entire light year of space left between them.

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