The sun isn’t a tidy sphere. If you go a little closer, you’ll see it looks a bit… fuzzy. Its plasma doesn’t sit as a smooth surface; it’s a roiling sea, throwing itself high above the sun, responding to magnetic fields that would tower many times over our entire planet in a way that would make any sane person feel very tiny indeed. So best not to think about the scale of it too much. We get enough existential panic from the possibility of a Michael Bay remake of Teenage Mutant Ninja Turtles.
Some of this plasma gets enough of a kick to leave the pull of the Sun altogether, and it heads out into the universe. It’s barely there – just some electrons and protons held together by the merest hint of a magnetic field. But it’s there. After about 18 hours, if it’s lucky, it’ll hit the Earth. Now, it might have whizzed passed Mercury and Venus, but the Earth is slightly different – we have a magnetosphere.