Almost all TV series like Two and a half men, Smallville, The big bang theory, etc. start in Sep/Oct and end in May/Jun with some weeks/months off in between. Their episodes are thrown at you almost every week or every two weeks.
But with some TV Shows like The Universe e.g. the 1st season starts in May (May 29, 2007) and ends in Sep. (Sep 4, 2007) and then the season 2 starts almost immediately in November Nov. 29, 2007 and ends in April 2008.
So my question is. Is there any strict time interval for the term "season" in the movie/TV industry or is it up to the creator/broadcaster?