The planet Endor is not visible in The Return of the Jedi.
Endor, also known as Tana among the Ewok species, was the cyan gas giant planet orbited by the forest moon of Endor. The name "Endor" was also sometimes used for the forest moon. The planet itself was less well known than the moon.
The following is taken from an article on Wookieepedia and clearly shows that Endor, the planet, exists. However, it is not visible in The Return of the Jedi.
The planet Endor was never visible in any scenes in Return of the Jedi set on the forest moon's surface.
Given that it is considered a gas giant, and thus uninhabitable, it is logical that the planet would not be featured prominently in the movie or expanded universe.