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.
The Eagle Nebula is a diffuse emission nebula. A nebula is a region of interstellar gas and dust. Emission nebulae are clouds of ionized gas.The ionization comes from an extr â¦ emely hot star that sends high-energy photons to the nebula. These nebulae usually appear reddish.eflection nebula are clouds of dust which are simply reflecting the light of a nearby star or stars. Such as the Witch Head Nebula. Emission nebula is a cloud of ionized gas (plasma) emitting light of various colors.