The celestial sphere is certainly a strange way to think about the night sky.

It makes sense to use globes to diagram the Earth. The Earth, after all, is a roughly spherical planet, and flat paper maps have a way of distorting distances.

The sky, though? Seriously? I mean, we all know the universe isn’t exactly a defined sphere that barely extends past Earth’s surface, right?

I mean, this model—the “celestial sphere”—even tries to claim that all the stars sit on the plane of the sphere like thumbtacks on a ceiling. And that the planets in the solar system follow regular paths around this odd-looking sphere.

Pretty strange way to think about the night sky, right?

Well…I have to say, astronomers do have a point. Continue reading →