How does a hypothesis become a theory

  A "hypothesis" is just an idea or proposal which someone comes up with to try and explain a given set of observations. A hypothesis must be:
 a) falsifiable/disprovable
b) testable
 c) have predictive value, in order to be taken seriously by scientists, and to begin its journey towards the status of "theory".
If it is an interesting proposal and is deemed to possess these 3 criterion, scientists will start to investigate it: what can it predict, what does it explain, is it compatible with all the relevant data/observations? If it is supported by enough experiments and/or observations, and gains acceptance by enough of the "scientific establishment" (ie, by enough scientists who are accepted and admired by their peers), at some undefinable point it becomes a "theory". It can still be disproven at any time, but until that happens it will remain a "theory" and may even graduate to the status of "well supported theory", such as the theory of gravity or relativity. At NO point, however, is ANY theory ever considered by scientists to have been "proven": in the scientific world, all truth is "relative". and provisional.

It comes a theory when you test it and it works.

The answer is telescope.