Marvel Time
In the Marvel Universe, ever since Fantastic Four volume 1 issue 1, the stories are almost always set in the present year that the comics are printed. The characters age very slowly. The main problem is that events in characters lives are tied in to real historical events. So this floating timeline must be fixed at some point.
The solution is that historical events in the Marvel universe do not take place at same time they do in the real universe. e.g. World War 2 takes place in the 1950s-60s. The millenium still takes place at the millenium. This way characters age at the correct rate.
Marvel time 1900s is historically equivalent to 1900-1905
Marvel time 1910s is historically equivalent to 1906-1911
Marvel time 1920s is historically equivalent to 1912-1919
Marvel time 1930s is historically equivalent to 1920-1925
Marvel time 1940s is historically equivalent to 1926-1931
Marvel time 1950s is historically equivalent to 1932-1939
Marvel time 1960s is historically equivalent to 1940-1947
Marvel time 1970s is historically equivalent to 1948-1953
Marvel time 1980s is historically equivalent to 1954-1959
Marvel time 1990s is historically equivalent to 1960-1999
Marvel time 2000s is historically equivalent to 2000-2039
As you can see, the stories printed in the 60s, 70s, 80s and 90s all take place in the 1990s. So events in the rest of the century have to be expanded to compensate.
Don't take what you read too seriously. It is Christmas when ever the writers feel like it. So time of year is best ignored.
Sometimes Marvel time is not always used by writers so there are contradictions. Sometimes events are referred back to in real time. Sometimes events in the past have been retconned/overwritten. Sometimes characters refer to events as a month ago when they only happened a week ago etc.
Let me give you an example why this works. Shadowcat is 13&1/2 in 1980. In 1987 she is almost 15. So you can see that 4 years of comics take place in one year.
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