The North Star Was A Different Star When The Egyptians Built Their Pyramids.

The more interesting part of this story, below, is actually old news, while the new part of the story is that the former North star, Thuban, has been recently discovered to be part of a binary star system, something that escaped detection for thousands of years despite the prominence of this star in the sky.

Although it's not the brightest star in the sky, Polaris serves as our guiding North Star. It's a steady star in the Ursa Minor constellation to guide by, remaining constant while the rest of the north sky moves. This is because Polaris is closest to Earth's north pole, so it appears that the other stars in the sky rotate around it. 

But Polaris hasn't always been our North Star. And during the construction of the earliest Egyptian pyramids 4,700 years ago, the pole star was Thuban, or Alpha Draconis, found in the Draco constellation. The star is 270 light-years from Earth. 

There is evidence now that Thuban was used to guide the construction of the pyramids, given how their placement, and even air shafts, align with the stars. 

The North Star changed because Earth's spin axis itself wobbles slowly over the course of 26,000 years, which alters the position of our pole and where it points in the sky.

From here.