NASA has a new Sun observatory spacecraft in space. She's called Iris and she opened her eyes for the first time last June. Now she's sending images that are challenging scientist's understanding of our home star, according to Bart De Pontieu, the IRIS science lead at Lockheed Martin:
We are seeing rich and unprecedented images of violent events in which gases are accelerated to very high velocities while being rapidly heated to hundreds of thousands of degrees. These types of observations present significant challenges to current theoretical models.
It's not back to square zero, but it seems our simulations were wrong and now scientists have to explain why the hell this new observed phenomena are happening.