A solar day (sunrise to sunrise) lasts two Mercurian years (176 Earth days).

The Brian Jonestown Massacre, Crushed (Methodrone, 1995)

I can study my geography from chickens
Named for Plymouth Rock and Rhode Island,
And from trees out of Canada.
No; I shall leave the chickens out.
I shall make a new geography of my own.
— Hilda Conkling (age ten), Geography (excerpt)