This week, discover the Sahara’s greener past, explore a mysterious cosmological force, marvel at a new concept for space ...

Editor’s note: A version of this story appeared in CNN’s Wonder Theory science newsletter. To get it in your inbox, sign up for free here. Picture the Sahara, and an inhospitable landscape of ...

Picture the Sahara, and an inhospitable landscape of endless sand dunes and barren rock comes to mind. That’s largely the case today, but 7,000 years ago the vast desert was an altogether ...