The Messier marathon was not invented by Charles Messier himself but rather by two American astronomers, Don Macholz and Tom Hoffelder in the 70`s. They first found out that all 110 Messier objects can be seen in one night. Meanwhile, the marathon has become popular in Europe as well.
The Messier marathon is a real challenge for every person attending it: to find all 110 Messier objects in one night, you have to chase some of them in the evening shortly before they disappear during dusk and others shortly after they appear in the predawn sky.
You start chasing during dusk with the objects of the fall and winter sky, then turn to the springsky and, during predawn, finish with the summer sky.
In average, you have to search, find and indentify 10 objects every hour,that means one object every 6 minutes! Therefore, it helps to identify the Messier objects at least once before the marathon in a clear night. So it is better to plan ahead of time.
Which time of the year is best for a Messier marathon?
At 50° latitude, in middle Europe, a Messier marathon can be run best in the middle of march till the middle of april. You may then see 107 objects at ideal conditions (good sight, no moonlight). At 30° latitude you may even see all 110 objects in one night if you are lucky!
Why is this the best time for the Messier marathon? The Messier objects donīt spread evenly over the sky. One can find a major gapin distribution close to the equinox. The sun can be found there at the end of march, which means, at this time all Messier objects can be found in the nightsky and can be seen at least during dawn.
More about that here.