Sh2-216 is a planetary nebula in the constellation Perseus. With an apparent diameter of about 3 moons, it is one of the closest and largest planetary nebulae in the sky. However, it is difficult to photograph or observe due to its very low brightness.
A planetary nebula consists of a shell of gas and plasma that has been ejected from an old star at the end of its life. However, the name is historically conditioned and misleading, as these nebulae have nothing to do with planets. The name comes from the fact that they usually appear spherical in the telescope and look like distant gas planets. There are around 1500 known examples in our Milky Way.
Planetary Nebula SH2-216