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.
A nebula (Latin for cloud; pl. nebulae, nebulae, nebulÃ¦ or) nebulas is an interstellar cloud of, dust, hydrogen helium and other ionized. Gases, originally nebula was a name for any diffuse astronomical, object including galaxies beyond The Milky. wayxamples of these types of nebulae are the Rosette Nebula and the Pelican Nebula. The size of these nebulae, known as HII regions, varies depending on the size of the original cloud of gas. New stars are formed in the nebulae.