Does the discipline of history have any convention in determining the difference between "current events" and "history"? How do professional historians determine when an event has passed from politics and into history? Is this a matter that historians approach on a case by case basis, or do different writers have different opinions?
For example, a popular rule of thumb sets the cut off at 10 years - everything before is history and everything since current events. What is the historian's version of this rule, if in fact any exists?
A related question on the distinction between History and Politics - moved out of comments in order to preserve the link.