The earliest Mardigras and Easter since 1913

Easter is really early this year, you can read some of the history and background to why the date of Easter changes in an article by Jay Scott Newman here.
I should really have started by saying Easter is early in the western church, because this year as most years Christians will celebrate Easter on two different days. So the western date this year is March 23rd but the date in many Orthodox churches is April 27th. You'll need to understand things about the Gregorian and Julian calendars, the vernal equinox and the Jewish feast of Passover and also about how the moon and planets move.
Confusingly the western and eastern calendars sometimes work in such a way that Easter does fall at the same time, like last year and then again in 2010 and 2011.
My colleague Dagmar Heller from Germany has written a good background piece about the challenges and issues involved in trying to agree a common date for Easter you can it read it here.