How did William Herschel's approach to studying nebulae differ from Messier's?

Answer

He actively sought them out to understand cosmic structure.

Unlike Messier, whose work was incidental to comet hunting, William Herschel actively sought out these faint objects using increasingly powerful telescopes he constructed himself to understand the structure of the cosmos.

How did William Herschel's approach to studying nebulae differ from Messier's?
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