Along with the brown bear, it is one of only two of the eight modern bear species not considered globally threatened with extinction by the IUCN. American black bears often mark trees using their teeth and claws as a form of communication with other bears, a behavior common to many species of bears.
Planetary nebulae are astronomical objects made up primarily of gaseous materials. They are extended in size and fuzzy in appearance, and generally show some degree of symmetry. The nebula is illuminated by a central star, which sometimes is too faint to be seen.
Ring Nebula Facts. 1  The Ring Nebula is a planetary nebula, these type of nebula are created when a small star sheds it mass at the end of its life span.  The core of the dead star remains in the form of white dwarf, it ionizes the surrounding gas producing an impressive light display.