Hours later....

Since everone seems to have gone to bed :-$ (or dinner or Baseball) - what about an easy one:

There is a single Messier object that has a causal link with a recorded event in human history: Which M, what kind of event, which year?

Of course mickal555 has priority putting forward the next question - but until he wakes up, maybe you just solve this and move on...

A very good night, everyone.

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Non sunt multiplicanda entia praeter necessitatem.