Not only does astronomy cover different branches of science, it also borrows concepts in fiber optics as well. Objective (optics) is also taken into account when it comes to science, or in this case, astronomy.

Objective (optics) means the optical part of a scientific instrument such as a telescope or microscope, that is responsible for gathering light from the observed specimen and makes sure that these light rays are then focused at different levels to produce the real image.

In space studies, Objective (optics) is the optical part of the telescope. It is the lens located at the end of the refractor or simply put, is the front end of the telescope, where people usually set and focus at a fixed point in the sky or at a long distance. This is not to be confused with the other end of the telescope, where people usually take a look on the area being fixed upon. The light gathering capability and the maximum distance it can take is dictated by the diameter or size of the lens. This means that the bigger the objective lens a certain telescope has, it means that the dimmer the object it is focused on and more details can be shown or seen.