Coronal Mass Ejections
The Sun's "Coronal Mass Ejections"  fit all the criteria  for similarity to the reported features of  "Flying Saucers".

The Sun has regular huge eruptions from its surface, and large quantities of material are hurled into space. These eruptions are known as  "Coronal Mass Ejections", and they can reach into space for a few millions of kilometers.

The really interesting thing about them, is that they accelerate away from the surface, and the  acceleration can continue for an average of about an hour, for 2 to 3 solar radii, about 2 million kilometers, after which they appear to "fall" back to the surface, rather than accelerate, as would be expected.

These "Coronal Mass Ejections" are also known to be associated with "spiraling or twisted magnetic fields". Most likely, some or all  of the ejected mass itself may be rotating.

They can be observed clearly because of their brightness compared to the Sun. The brightness can even increase as they travel away from the Sun, when it could be argued that they would rapidly cool, and become darker. They may be creating an external light source.