A few points, and yes, this is new to me.
1. How did the name Black Knight stick? Obviously it is black.
2. If this is extra-terrestrial in origin, I would not initially think it friendly....It has a menacing appearance.
3. In the NASA pic, are those large cloud patterns on Earth? Or, are those icecaps/frozen tundra, as the photo purportedly is above the polar cap?
4. Size estimate...anyone?
5. WHAT IS YOUR GUESS AS TO WHAT THIS IS?
6. Save screenshots, especially showing the NASA website as the url.....because if this starts to go viral, guess what?