Who wrote this short story

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A few years back I read a short story in a sci-fi short story collection. I can't remember who wrote it, and I was hoping the following summary would ring a bell for one of y'all

A colony was started on this planet, the people not knowing that every 17 years or so a second star comes into the system, making the planet uninhabitable except at the poles. so every 17 years all the settlers have to take everything they can carry and head north to the pole to wait it out. Over the generations they've been doing this they've lost a lot of technology, and now most people think the idea that their ancestors arrived at the planet in a big metal ship is just myth.
The main character is the only one in his village who firmly believes the truth. the time to flee to the north pole is coming up and he's mad because he can't take all his books, because there's only a limited amount of stuff they can carry

A guy who looks weird shows up in town, claiming to be from another village. Eventually he confides in the MC that he's actually a scout from the humans that live on other planets. He says that they want to come and help, but because of space problems it might be decades before they can. They definitely will tho. But the MC has to stop talking about the people who live on other planets, it just agitates everybody and isn't helping. The MC of course agrees with the spaceman, because he doesn't want to fuck anything up, and promises not to talk about the space people anymore.
The end is it turns out the spaceman is actually just some dude from a couple villages over that they mayor ran into while preparing for the poleward evacuation at a neighboring village. He set the whole thing up just to get the MC to stop talking nonsense about there being people in space or their ancestors arriving in metal boats from space.