Sh 2-68
Sh 2-68 is a planetary nebula located in the constellation Serpens. It is the remnant of a low to intermediate mass star that has shed its outer layers, leaving behind a glowing shell of ionized gas illuminated by its central white dwarf star. Estimated to be 30,000 to 45,000 years old, Sh 2-68 is notable for its interaction with the surrounding interstellar medium, which has stalled the nebula's expansion and created an extended tail structure, giving it a distinctive asymmetrical appearance.
It has a proper motion of 53.2 +/- 5.5 mas yr-1, the largest value for a planetary nebula ever found.