There's a reason QVC is not the Science channel.

While recently hawking some boyfriend cardigans, host Jane Treacy and celebrity designer Isaac Mizrahi went way off script when they got into a spirited debate about whether the moon is a planet or a star.

Yes, the pair dove knee deep into an astronomy lesson that would have NASA doing a big ol' face palm.

Give 'em this, though: the banter was certainly more interesting than the give-and-take QVC usually provides.