Final answer:
The name of the protective outer layer that covers the posterior five-sixths of the eye is the sclera. It is the white, opaque part of the eye composed of connective tissue and is part of the fibrous tunic layer.
Step-by-step explanation:
The protective outer layer covering the posterior five-sixths of the eye is known as the sclera. The sclera is part of the fibrous tunic, which is the outermost layer of the eye that also includes the transparent cornea. The cornea covers the anterior tip of the eye and allows light to enter. On the other hand, the sclera is commonly referred to as the "white of the eye" and is made up primarily of connective tissue.
Although the sclera covers most of the eye's surface, it is not visible in its entirety. In humans, the visibility of the sclera is quite unique compared to that of many other species. The eye contains two additional layers beyond the fibrous tunic: the vascular tunic, comprising the choroid, ciliary body, and iris, and the neural tunic, or retina, which is responsible for photoreception.
The name of the protective outer layer covering the posterior five-sixths of the eye is the sclera. The sclera is the white part of the eye that is visible when looking at someone's eye. It covers most of the surface of the eye, providing protection and structural support.