sentences:  This idea was later discarded because the nucleus and the ring have the same redshift, and because more advanced telescopes revealed the knotty structure of the ring, something that would not be visible if the ring were the product of gravitational lensing.Many of the details of the galaxy remain a mystery, foremost of which is how it formed.So-called "classic" ring galaxies are generally formed by the collision of a small galaxy with a larger disk-shaped galaxy.