10 Biggest Unanswered Star Trek Mysteries

4. The Nexus

The Nexus (or at least the entry point to it) is a destructive temporal energy wave that crosses through the galaxy every 39.1 years.

In 2332 the Enterprise-B was nearly crippled attempting to save two refugee ships from it, in 2371 Captain's Kirk and Picard emerged from it to save the 230 million-strong population of Veridian III, and in 2410 it'll return again. Picard is set just over 10 years before that, in 2399.

Given the potential implications of using the Nexus - someone could, theoretically, use it jump to any point in time or space to change the course of history - should any Star Trek series make it to that year, it'll have to come around again.

What its true power is, where it comes from, and who might use it are all mysteries just waiting to be solved.