PN A66 78 (Abell 78)
Not one of HST's favored children, this planetary nebula is not available in enough filters to create a color image. I went ahead and gave it a fictitious color palette, and although the color is fake, it is not entirely unrealistic. The nebula emits strongly in [O III], giving it a greenish cyan coloration. The central stars of planetary nebulas tend to be blue, while other stars are comparatively yellow or red.
Many of the details are rather faint, especially the hazy outer shell, but I think it is a very beautiful object. Most planetary nebulas are. This one is said to be "born again" as it experienced some kind of secondary event after its initial formation, leading to some extra ejected material.
Data from the following proposal were used to create this image:
All channels: WFC3/UVIS F502N
North is 64.36° counter-clockwise from up.