Which specific Martian opposition event initiated Lowell’s detailed mapping and public campaign regarding Martian canals?

Answer

1894

The critical moment when Lowell’s long campaign of Mars observation truly began was centered around the Martian opposition of 1894, allowing him to make his first detailed mappings.

Which specific Martian opposition event initiated Lowell’s detailed mapping and public campaign regarding Martian canals?
MarsastronomyobservationPercival Lowell