What is the Most Beautiful Thing in the Known Universe?
DanS — (archived)
According to B.Sc. Mechanical Engineer Karim Adel of Egypt it would have to be Minkowski 2-9 (M2-9) ... not to be confused with Messier Catalog M2, the Globular Cluster in Aquarius. M2-9 is the Twin Jet Nebula, also called Minkowski's Butterfly, the Wings of a Butterfly Nebula, or just Butterfly Nebula.
The above linked video begins with a ground-based view of the night sky, before zooming in on M2-9, a bipolar planetary nebula, as seen by the NASA/ESA Hubble Space Telescope.